铅超富集植物金丝草对Pb胁迫的响应机制研究
|
摘要
土壤重金属污染已成为当前环境科学界关注的重大问题，其中Pb污染受到大家普遍关注。污染土壤的Pb可通过食物链进入人体，严重影响体内新陈代谢，而且人体内的Pb靠自身排除很慢，其损害机体器官的过程不可逆。因此，Pb污染土壤的治理已成为当前亟需解决的重大课题。传统的重金属污染治理多采用客土法、淋溶法和施用化学改良剂等物理化学方法，不仅费用昂贵，只能小面积应用，且容易造成二次污染，不能从根本上解决问题。近年来，人们发现了一些植物对重金属具有特殊的吸收富集能力，利用这类植物修复重金属污染的植物修复技术是一项高效、环保和低廉的治理措施，具有十分广阔的应用前景。
重金属污染植物修复技术应用的前提是发现重金属超富集植物，由于Pb具有较高的负电性，易与土壤中的有机质和铁锰氧化物形成共价键，不易被植物吸收，因此，目前国内外发现的Pb超富集植物极少。导师课题组前期研究在国内首次发现了Pb超富集植物—金丝草(Pogonatherum crinitum)，可在土壤Pb含量高达17496mg/kg的铅锌矿区正常生长，对Pb有极强的耐性和富集能力，且超过Pb超富集植物的标准。金丝草的这种特性是长期适应Pb胁迫环境的结果，是长期进化过程中形成的特殊适应性，可能存在着特殊的生态学适应意义，蕴藏着需要人们去认识和发掘的形态学和生理学适应机制，但目前有关金丝草对Pb的耐性和富集机制尚不清楚，特别是金丝草适应高浓度铅的可能形态学和生理学途径缺乏足够的了解，很大程度上限制了Pb富集植物在Pb污染土壤治理中的应用。
鉴于此，本文根据植物抗逆生理学、生态毒理学、根系生物学的原理和方法，以导师课题组首次发现的Pb超富集植物金丝草为研究对象，以同为禾本科的百喜草（Paspalum natatu）为对照。采用Pb胁迫土培模拟试验，设计同质与异质Pb胁迫装置，利用BTC根系动态监测仪、根系图像分析仪、Lci便携式光合仪、Agilen-t7890N气相色谱仪、SPAD502plus叶绿素仪、OP-30P型便携式叶绿素荧光仪、原子吸收分光光度计等手段，定量研究金丝草对不同浓度Pb胁迫的形态学和生理学过程的响应，比较金丝草和百喜草在Pb胁迫条件下形态学和生理学响应指标的差异，分析Pb胁迫条件下金丝草对Pb的富集及转运能力，揭示金丝草适应环境高浓度Pb的可能形态学和生理学途径，为阐明Pb超富集植物对Pb的耐性和富集机制提供科学依据，对于发掘Pb超富集植物对Pb的富集潜力、加快修复土壤Pb污染具有重要理论和现实意义。论文主要研究结果如下：
（1）轻度Pb胁迫（50mg·L~(-1)和150mg·L~(-1)）对金丝草种子发芽势、发芽率、发芽指数和活力指数均有一定促进作用，随胁迫浓度的增大，种子萌发的各项指标均受到较大抑制；金丝草种子在Pb胁迫浓度为800mg·L~(-1)时，仍有一定萌发能力；Pb胁迫对金丝草根长和芽长无显著影响。
（2）同质Pb胁迫对金丝草苗高无显著影响。不同Pb胁迫浓度处理下，金丝草苗高和叶最大伸展均表现为7和8月生长较快，10月生长最小；Pb胁迫条件下，金丝草可通过提高根系生物量分配，萌蘖更新速度加快，将Pb转移至体外，实现自身解毒，适应Pb胁迫环境，这是金丝草适应高浓度Pb胁迫的重要机制之一。
（3）在异质Pb胁迫初期（30d）金丝草苗高、叶最大伸展和分蘖均受到一定抑制，但随胁迫时间的增加，抑制作用逐渐减小；异质Pb胁迫条件下，金丝草苗高在7月增长最大，10月最小，6月和8月相近；金丝草无Pb左室、Pb胁迫右室及整株的根冠比均表现为先增大后减小。低浓度Pb胁迫条件下，金丝草根系生物量分配较多，而随Pb胁迫浓度的增大，生物量分配更倾向于地上部分。高浓度Pb胁迫条件下，金丝草可通过提高地上部分生物量分配，将土壤中的Pb转移至地上部分；
（4）同质Pb胁迫条件下，金丝草根长、表面积均受到一定抑制。随Pb胁迫浓度的增大，总根长和表面积均先增大后减小，总根长在Pb浓度500mg·kg~(-1)时达最大（621.05cm），根总表面积在Pb浓度2500mg·kg~(-1)时达最大（20.29cm2）；Pb胁迫对金丝草根平均直径和体积抑制作用不明显；金丝草可通过根的快速伸长，以避让Pb胁迫，从而适应高浓度Pb胁迫环境。
（5）不同异质Pb胁迫条件下，金丝草总根长和表面积均表现为无Pb左室大于Pb胁迫右室；在无Pb左室，百喜草根长均大于金丝草，但在Pb胁迫右室，金丝草总根长则大于百喜草；随Pb胁迫浓度的增大，金丝草根表面积和平均直径均表现出逐渐增大的趋势。
（6）BTC根系动态监测系统对金丝草根系动态监测表明，同质Pb胁迫条件下，仅在150mg·kg~(-1)和2500mg·kg~(-1)处理观测到金丝草根系，根系进入Pb胁迫斑块的概率为28.57%。异质Pb胁迫条件下，仅1000mg·kg~(-1)处理在9月和10月观测到金丝草根系，根系进入Pb胁迫斑块的概率仅为14.28%，小于同质Pb胁迫处理；在重度Pb胁迫条件下，8月-9月金丝草根表面积和体积增加大于轻度Pb胁迫处理，而根长和平均直径则相反。
（7）同质Pb胁迫条件下，金丝草叶片光合速率（Pn）和气孔导度（Gs）在Pb胁迫中期（9月）受到明显抑制作用，但胁迫初期（8月）和末期（10月）抑制不明显，且在Pb胁迫浓度150mg·kg~(-1)和1500mg·kg~(-1)处理，在胁迫初期光合速率（Pn）和气孔导度（Gs）加快；随Pb胁迫浓度的增大，金丝草叶片的蒸腾速率（Tr）减小。金丝草可通过提高光合特性，降低蒸腾速率，加快抗逆物质的很成，保证自身生长。
（8）异质Pb胁迫条件下，金丝草叶片光合速率（Pn）、气孔导度（Gs）和胞间CO2浓度（Ci）均受到一定抑制，但除胁迫中期（9月）金丝草光合速率受到明显的抑制外，其他光合特性指标在不同胁迫时期抑制作用均不明显；
（9）同质和异质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）均先减小后增大，在中午12时达最大，然后逐渐减小，呈正态分布；胞间CO2浓度（Ci）则表现为先减小后增大，在中午12时最小。
（10）同质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片可变荧光Fv和PSⅡ最大光化学效率均先减小后增大，PSⅡ潜在活性则先增大后减小；不同Pb胁迫浓度，不同胁迫时间，金丝草叶片PSⅡ最大光化学效率和PSⅡ潜在活性均大于无Pb对照；Pb胁迫对金丝草叶片荧光特性有一定促进作用。
（11）同质和异质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片SPAD值呈逐渐减小的变化规律。随Pb胁迫浓度的增大，金丝草叶片SPAD值呈“W”型的变化规律，但不同Pb胁迫处理金丝草叶片SPAD值均与对照无显著差异（P＜0.05）。Pb胁迫对金丝草叶片SPAD值抑制不明显。
（12）轻度Pb胁迫（150mg·kg~(-1)）对金丝草叶片叶绿素a、叶绿素b和叶绿素总量均有一定促进作用，高浓度Pb胁迫对叶绿素b有一定促进作用；随胁迫浓度和时间的增加，Pb胁迫对金丝草叶片叶绿素的抑制作用逐渐增大。
（13）同质和异质Pb胁迫条件下，随Pb浓度的增大，金丝草叶片POD、SOD和MDA含量均逐渐增大，金丝草叶片POD、SOD和MDA含量均远大于百喜草，而CAT含量则表现为百喜草大于金丝草。Pb胁迫条件下，金丝草通过提高POD和SOD活性，增大膜脂化反应，以适应Pb胁迫环境，这是金丝草耐Pb的重要生理机制之一；
（14）同质Pb胁迫条件下，金丝草根系中含的主要有机酸为草酸、柠檬酸和苹果酸，且随Pb胁迫浓度的增大表现出逐渐增大的趋势；金丝草地上部分含的主要有机酸为草酸；异质Pb胁迫条件下，金丝草根系和地上部分低分子有机酸主要以草酸、丙二酸、苹果酸和柠檬酸为主，还含有少量反丁烯二酸，其中草酸含量最高，其次为苹果酸和柠檬酸。金丝草主要通过草酸的螯合作用，达到对Pb胁迫的解毒。
（15）重度Pb胁迫条件下，金丝草地上部分Pb全量显著大于其他处理及无Pb对照（P＜0.05），且含量大于1000mg·kg~(-1)，达到Pb超富集植物地上部分Pb富集量的标准；转移系数随Pb胁迫浓度的增大，在胁迫浓度2500mg·kg~(-1)处理为1.153＞1，超过Pb超富集植物转移系数大于1的标准；金丝草对Pb胁迫有较强耐性，而且可将大量土壤中Pb转移到地上部分，达到修复土壤Pb污染的目的；金丝草具有强的转运土壤中Pb的能力，然后通过地上部分的凋落将Pb移出，这是金丝草耐Pb特性的重要机制之一；
（16）同质和异质Pb胁迫条件下，不同Pb胁迫处理，金丝草地上部分和根系中Pb均主要以盐酸提取态存在，乙醇提取态和残渣态在低浓度和高浓度Pb胁迫处理间存在一定差异。同质Pb胁迫条件下，金丝草地上部分盐酸提取态Pb占79.04%-94.37%，根系占70.61%-85.92；异质Pb胁迫条件下，金丝草体内残渣态Pb含量所占比例增加，乙醇提取态所占比例减小；Pb胁迫条件下，金丝草体内Pb的迁移能力降低，从而减轻Pb的毒害作用。
（17）同质Pb胁迫条件下，随Pb浓度的增大，金丝草凋落体中乙醇提取态和盐酸提取态Pb含量及总Pb含量均先增大后减小，残渣态Pb含量则逐渐增大；异质Pb胁迫条件下，随Pb浓度的增大，金丝草凋落体内乙醇提取态Pb含量先增大后减小，盐酸提取态Pb含量逐渐增大，残渣态出现增大减小的波动；金丝草可通过植物组织的凋亡过程，将体内Pb移出，以达到自我解毒的目的。
综上所述，Pb超富集植物金丝草对Pb胁迫的响应表现为多途径的适应机制：首先，在高浓度Pb胁迫条件下金丝草可通过根的快速伸长，寻觅无Pb斑块，避让Pb胁迫，在无法避让时则对Pb产生“滞吸”作用。其次，可通过加快光合速率（Pn）和气孔导度（Gs），降低蒸腾速率（Tr），促进叶绿素合成、提高可变荧光Fv、PSⅡ最大光化学效率和PSⅡ潜在活性，加快金丝草抗逆性物质的合成，提高地上部分生物量分配，将土壤中的Pb转移至地上部分，然后通过加快地上部分的萌蘖更新，借助凋落将Pb移至体外，实现自身解毒；最后，金丝草还可通过提高体内POD和SOD活性，增大膜脂化反应，加快体内草酸、柠檬酸和苹果酸的分泌，螯合进入体内的Pb，将Pb转化为难溶态，减轻Pb胁迫对植物的伤害，以适应Pb胁迫环境。
Soil heavy mental pollution has become one of the current hot topics in environmentalscientific community. Pb pollution in environmental pollution of heavy metal is most prominent.Soil Pb pollution can enter into human body through the food chain quickly, this affectmetabolism of human body seriously. Besides the process which human body release Pb by itselfis very slow, the damage to organs in the body is irreversible. Therefore, Pb pollution treatmenthas become an urgent subject currently. Traditional method of treatment to heavy metal pollutionin soil mainly use mixing of soil, leaching method, chemical modifiers ect. Such physical andchemical methods which are not only expensive and cannot apply in small areas but also causedsecond pollution, such methods cannot solve the Pb pollution in soil fundamentally. In recentyears, people have found the bioconcentration ability of some plants to heavy metals. It is a highefficiency, environmental protection and cost control measures to use such plants asphytoremediation of heavy metal pollution. This treatment measure has a very broad applicationprospects.
The prerequisite to the application of phytoremediation to heavy metal contaminated soilswas the discovery of heavy metal hyperaccumulators. Pb is not easy be absorbed by plant for thehigher electronegativity of Pb, and easy form a covalent bond with the soil organic matter andFe-Mn oxide. Currently rare hyperaccumulators were found at home and abroad. Pbhyperaccumulator plant—Pogonatherum crinitum was found by our research teem previous forthe first time in China, which can grow normally in the lead-zinc mining area of high content ofPb up to17496mg·kg~(-1). This plant has strong tolerance and accumulation ability of Pb, and overof Pb hyperaccumulator standard. But currently it is still not clear of the tolerance andaccumulation mechanism of Pogonatherum crinitum to Pb, especially not so clear howPogonatherum crinitum react by physiological ecology characteristics under high Pbconcentration. These problems limit the application of Pogonatherum crinitum in the remediationof Pb polluted soil.
Based on these researches and studies, according to the principle and method of plantresistance physiology, toxicology, root biology, taking Pb hyperaccumulator Pogonatherumcrinitum which was first found by our research group as the research object, meanwhile selecting Paspalum natatu which is included in the same grass family as a control, simulation Pb stress testin the lab was taken, designed homogeneity and heterogeneity Pb stress test with manyinstruments including BTC root dynamic monitor, root image analyzer, Lci portablephotosynthetic apparatus, atomic absorption spectrophotometer, ect.Morphology and physiologyreaction was tested under different Pb stress condition, accumulation and transport capacity of Pbby Pogonatherum crinitum and Paspalum natatu was compared, the possible physiologicalecology way of Pogonatherum crinitum adopt to enrionment was revealed. This can also providescientific basis to clarify the hyperaccumulator plants resistant to Pb and Pb rich mechanism. Ithas important theoretical and practical significance for accelerating the repair of soil Pb pollutionand discover potential rich Pb characteristics of Pb Hyperaccumulator. The main results are asfollows:
(1) Low concentration of Pb stress (50mg·L~(-1)and150mg·L~(-1)) had positive effect onPogonatherum crinitum seeds germination potential, germination rate, germination index andvigor index. But with the increase of Pb stress concentration, the germination of the seed indexwas gradually decreased. Pogonatherum crinitum still had certain germination ability under Pbstress concentration of800mg·L~(-1). The effect on the shoot, root and seedling growth inhibition ofPb stress of Pogonatherum crinitum was not obvious.
(2) Homogeneous Pb stress had no significant inhibitory effect on the growth of Pogonatherumcrinitum. Seedings of Pogonatherum crinitum rapid growth in July and August, the growth inOctober was smallest. Pogonatherum crinitum could increase root biomass allocation adapt to Pbstress environment.Pb stress could accelerate the sprout updation of Pogonatherum crinitum, thisprobably was one mechanism of Pogonatherum crinitum adapt to high concentration.
(3) Pogonatherum crinitum seedling height, sprout tiller had some inhibitory effect at early stageof heterogeneous stress (30d), but with the time increasing of Pb stress, inhibition is less and lessunder heterogeneous Pb stress condition. Under heterogeneous Pb stress condition Pogonatherumcrinitum seedling height increase to the maximum in July, minimum in October, seedling height inJune and August are same. Biomass allocate more to root part under low Pb concentration stresscondition, but with the increase of Pb concentration, biomass allocation to shoot more, whichmore Pb could transfer to shoot.
(4) Pb stress had inhibitory effect on root length and surface area of Pogonatherum crinitum underHomogeneous Pb stress condition. Along with the increase of Pb concentration, total root lengthand surface area of the root were increased first and then decreased. Root length grows up tomaximum of621.05cm at Pb stress concentration500mg·kg~(-1)treatment, root surface area growsup to a maximum of20.29cm2at Pb stress concentration2500mg·kg~(-1)treatment. Pb stress had noobvious inhibition on the root average diameter and volume of Pogonatherum crinitum.Pogonatherum crinitum could avoid Pb stress by root growth to adapt to the higly Pbconcentration stress environment.
(5) Total root length and surface area of Pogonatherum crinitum on left compartments was greaterthan right compartments with Pb stress concentration increased under heterogeneous Pb stresscondition. Root length of Paspalum natatu in left compartments without Pb stress under differentPb stress condition were greater than Pogonatherum crinitum, but root length of Pogonatherumcrinitum in right compartments were greater than Paspalum natatu. Along with the increase of Pbconcentration, the root surface area and average diameter of Pogonatherum crinitum increasedunder higly Pb concentration condition.
(6) Root could be observated in the treatment of Pb concentration of150mg·kg~(-1)and2500mg·kg~(-1)at homogeneity of Pb stress conditions by BTC dynamic monitoring system, theprobability of root growing into Pb stress plaque was28.57%. In Higly Pb concentration (2500mgkg~(-1)) plaque, root surface area and root volume increased more than the low Pb concentration(150mg kg~(-1)) plaque from August to September, the the changes of root length and diameter wereantithetical. Root could be observated at Pb concentration of1000mg·kg~(-1)treatment. Theprobability of root growing into Pb stress plaque was14.28%under heterogeneous Pb stresscondition in the season of September and October, this means Pogonatherum crinitum hasdcertain avoidance of Pb stress.
(7) Photosynthesis rate (Pn) and stomatal conductance (Gs) of Pogonatherum crinitum weresignificant inhibited in medium test term (September) under homogeneous Pb stress conditions,but less inhibitory effect in Pb stress test initial stage and last phase, and quickly increased atinitial stage of Pb concentration of150mg·kg~(-1)and1500mg·kg~(-1)treatments. Photosynthesis rate(Pn) and stomatal conductance (Gs) of Paspalum natatu were smaller than control at different testtime. Intercellular CO2concentration (Ci) of Pogonatherum crinitum had no significant difference with control at different stress time under homogeneous Pb stress conditions.Transpiration rate (Tr)of Pogonatherum crinitum decreased. Pogonatherum crinitum could reduce the transpiration inorder to ensure its growth.
(8)Various photosynthetic characteristics of Pogonatherum crinitum were inhibited underheterogeneous Pb stress conditions, except photosynthetic rate of Pogonatherum crinitum wasinhibited significantly in stress medium term(September), other stress times inhibitory effect werenot obvious.
(9) Leaf photosynthesis rate (Pn), stomatal conductance (Gs) and transpiration rate(Tr) ofPogonatherum crinitum were first decreased and then increased, reached a maximum value at12:00, then decreased gradually, while the intercellular CO2concentration(Ci) first decreased andthen increased, reached a minimum value at12:00under homogeneous and heterogeneous Pbstress condition.
(10) With increased of stress time, Pogonatherum crinitum leaf variable fluorescence Fv and themaximal photochemical efficiency of PSⅡ first decreased then increased, PSII potential activityincreased first and then decreased under homogeneous Pb stress:. In different heterogeneous Pbstress concentration and different stress time, PSⅡmaximal photochemical efficiency and PSⅡpotential activity were more than control which without Pb stress. This means that Pb stresspromoted the fluorescence properties of Pogonatherum crinitum.
(11) Leaf green degree of Pogonatherum crinitum decreased substantially with the increase ofstress time under homogeneous and heterogeneous Pb stress conditions. With the increase of Pbstress concentration, leaf green degree of Pogonatherum crinitum was W–shape changed, butdifferent Pb stress treatments had no significant difference with the control (P <0.05). Pb stresshad a certain inhibitory effect on leaf green degree.
(12) Pb stress had a certain inhibitory effect on the chlorophyll content of Pogonatherum crinitum,except lower Pb concentration of150mg·kg~(-1)treament could promote Chlorophyll a, chlorophyllb, total chlorophyll and chlorophyll a/b of Pogonatherum crinitum under homogeneous Pb stress.With the increase of Pb stress concentration the inhibition increased.
(13) The content of POD、SOD and MDA in Pogonatherum crinitum leaf is more than Paspalumnatatu while CAT in Pogonatherum crinitum leaf is less than Paspalum natatu both underhomogeneous and heterogeneous Pb stress conditions. This indicates that Pogonatherum crinitum under Pb stress condition increase SOD and POD activity to increase membrane lipid reaction toadapt Pb stress environment, this is one of the physiological mechanism of Pogonatherumcrinitum resistant to Pb sress.
(14) Main organic acids in root part of Pogonatherum crinitum include Oxalic acid, citric acid andmalic acid, and showed gradually increased trend along with increased of Pb stress concentrationunder homogeneous Pb stress conditions. Under heterogeneous Pb stress conditions, root andshoot in Pogonatherum crinitum had low molecular organic acid mainly include oxalic acid,malonic acid, malic acid and citric acid, the oxalic acid content is the highest, followed by malicacid and citric acid. Pogonatherum crinitum can reach to detoxification of Pb stress mainlythrough the effect of oxalic acid chelate.
(15) Total Pb content in shoot under higher Pb stress condition significantly greater than othertreatments and control, and Pb content in shoot and Pb transfer index were exceed the standard ofPb hyperaccumulation. Pogonatherum crinitum has strong transport of soil Pb, and based on thepart of the litter make Pb out of body, this may be one of the mechanisms of Pogonatherumcrinitum resistance Pb stress.
(16) The form of Pb in shoot and root of Pogonatherum crinitum under different Pb stresstreatments in both homogeneous and heterogeneous Pb stress condition were mainly HClextraction, ethanol extraction and residual Pb existed certain difference. HCl extraction Pbaccounted for70.61%-85.92in root and79.04%-94.37%in shoot under homogeneous Pb stresscondition.The residual Pb content in plant increased but ethanol extraction Pb dcreased, whichshows that Pb in Pogonatherum crinitum could component chelating, lower ability of migration,thereby reducing the toxicity of Pb.
(17)Ethanol and HCl extractable Pb content and total Pb content increased first and thendecreased, the residue Pb content increased with the increase of Pb concentration underhomogeneous Pb stress condition. Ethanol extractable Pb content increased first then decreased,HCl extractable Pb content increased with the increase of Pb concentration under heterogeneousPb stress condition. Total Pb and different form Pb content in apoptosis body of Pogonatherumcrinitum were higher than Paspalum natatu, which drawed the results Pogonatherum crinitumcould remove Pb out of body through the apoptosis of plant tissue, in order to detoxification.
In summary response mechanism of Pb hyperaccumulator Pogonatherum crinitum under Pb stress mainly include: firstly, Pogonatherum crinitum through the rapid elongation of root, find noPb patch, to avoid the Pb stress, so as to adapt to the high Pb concentration environment, but rootwill absorb Pb from soil after a period when can not avoid Pb stress. Then Pogonatherum crinitumcan increase photosynthetic rate (Pn) and stomatal conductance (Gs), decrease the transpirationrate (Tr), promote chlorophyll synthesis, improve the variable fluorescence Fv, the maximalphotochemical efficiency of PSⅡ and PSⅡ potential activity, increase synthesis of biomass,improve root biomass allocation adaptive Pb stress environment under Pb concentrationconditions, by improving the biomass distribution of shoot, transfer Pb in soil to overground part,then accelerate sprouting update rate, through fallen litter take Pb out off body, realize their owndetoxification under High concentration Pb stress. In addition, Pogonatherum crinitum canincrease POD and SOD activity, increased membrane lipid peroxidation reaction, by increasingsecrete more citric acid and malic acid, chelation of Pb in body, transform Pb into insoluble state,to achieve detoxification of Pb stress.
重金属污染植物修复技术应用的前提是发现重金属超富集植物，由于Pb具有较高的负电性，易与土壤中的有机质和铁锰氧化物形成共价键，不易被植物吸收，因此，目前国内外发现的Pb超富集植物极少。导师课题组前期研究在国内首次发现了Pb超富集植物—金丝草(Pogonatherum crinitum)，可在土壤Pb含量高达17496mg/kg的铅锌矿区正常生长，对Pb有极强的耐性和富集能力，且超过Pb超富集植物的标准。金丝草的这种特性是长期适应Pb胁迫环境的结果，是长期进化过程中形成的特殊适应性，可能存在着特殊的生态学适应意义，蕴藏着需要人们去认识和发掘的形态学和生理学适应机制，但目前有关金丝草对Pb的耐性和富集机制尚不清楚，特别是金丝草适应高浓度铅的可能形态学和生理学途径缺乏足够的了解，很大程度上限制了Pb富集植物在Pb污染土壤治理中的应用。
鉴于此，本文根据植物抗逆生理学、生态毒理学、根系生物学的原理和方法，以导师课题组首次发现的Pb超富集植物金丝草为研究对象，以同为禾本科的百喜草（Paspalum natatu）为对照。采用Pb胁迫土培模拟试验，设计同质与异质Pb胁迫装置，利用BTC根系动态监测仪、根系图像分析仪、Lci便携式光合仪、Agilen-t7890N气相色谱仪、SPAD502plus叶绿素仪、OP-30P型便携式叶绿素荧光仪、原子吸收分光光度计等手段，定量研究金丝草对不同浓度Pb胁迫的形态学和生理学过程的响应，比较金丝草和百喜草在Pb胁迫条件下形态学和生理学响应指标的差异，分析Pb胁迫条件下金丝草对Pb的富集及转运能力，揭示金丝草适应环境高浓度Pb的可能形态学和生理学途径，为阐明Pb超富集植物对Pb的耐性和富集机制提供科学依据，对于发掘Pb超富集植物对Pb的富集潜力、加快修复土壤Pb污染具有重要理论和现实意义。论文主要研究结果如下：
（1）轻度Pb胁迫（50mg·L~(-1)和150mg·L~(-1)）对金丝草种子发芽势、发芽率、发芽指数和活力指数均有一定促进作用，随胁迫浓度的增大，种子萌发的各项指标均受到较大抑制；金丝草种子在Pb胁迫浓度为800mg·L~(-1)时，仍有一定萌发能力；Pb胁迫对金丝草根长和芽长无显著影响。
（2）同质Pb胁迫对金丝草苗高无显著影响。不同Pb胁迫浓度处理下，金丝草苗高和叶最大伸展均表现为7和8月生长较快，10月生长最小；Pb胁迫条件下，金丝草可通过提高根系生物量分配，萌蘖更新速度加快，将Pb转移至体外，实现自身解毒，适应Pb胁迫环境，这是金丝草适应高浓度Pb胁迫的重要机制之一。
（3）在异质Pb胁迫初期（30d）金丝草苗高、叶最大伸展和分蘖均受到一定抑制，但随胁迫时间的增加，抑制作用逐渐减小；异质Pb胁迫条件下，金丝草苗高在7月增长最大，10月最小，6月和8月相近；金丝草无Pb左室、Pb胁迫右室及整株的根冠比均表现为先增大后减小。低浓度Pb胁迫条件下，金丝草根系生物量分配较多，而随Pb胁迫浓度的增大，生物量分配更倾向于地上部分。高浓度Pb胁迫条件下，金丝草可通过提高地上部分生物量分配，将土壤中的Pb转移至地上部分；
（4）同质Pb胁迫条件下，金丝草根长、表面积均受到一定抑制。随Pb胁迫浓度的增大，总根长和表面积均先增大后减小，总根长在Pb浓度500mg·kg~(-1)时达最大（621.05cm），根总表面积在Pb浓度2500mg·kg~(-1)时达最大（20.29cm2）；Pb胁迫对金丝草根平均直径和体积抑制作用不明显；金丝草可通过根的快速伸长，以避让Pb胁迫，从而适应高浓度Pb胁迫环境。
（5）不同异质Pb胁迫条件下，金丝草总根长和表面积均表现为无Pb左室大于Pb胁迫右室；在无Pb左室，百喜草根长均大于金丝草，但在Pb胁迫右室，金丝草总根长则大于百喜草；随Pb胁迫浓度的增大，金丝草根表面积和平均直径均表现出逐渐增大的趋势。
（6）BTC根系动态监测系统对金丝草根系动态监测表明，同质Pb胁迫条件下，仅在150mg·kg~(-1)和2500mg·kg~(-1)处理观测到金丝草根系，根系进入Pb胁迫斑块的概率为28.57%。异质Pb胁迫条件下，仅1000mg·kg~(-1)处理在9月和10月观测到金丝草根系，根系进入Pb胁迫斑块的概率仅为14.28%，小于同质Pb胁迫处理；在重度Pb胁迫条件下，8月-9月金丝草根表面积和体积增加大于轻度Pb胁迫处理，而根长和平均直径则相反。
（7）同质Pb胁迫条件下，金丝草叶片光合速率（Pn）和气孔导度（Gs）在Pb胁迫中期（9月）受到明显抑制作用，但胁迫初期（8月）和末期（10月）抑制不明显，且在Pb胁迫浓度150mg·kg~(-1)和1500mg·kg~(-1)处理，在胁迫初期光合速率（Pn）和气孔导度（Gs）加快；随Pb胁迫浓度的增大，金丝草叶片的蒸腾速率（Tr）减小。金丝草可通过提高光合特性，降低蒸腾速率，加快抗逆物质的很成，保证自身生长。
（8）异质Pb胁迫条件下，金丝草叶片光合速率（Pn）、气孔导度（Gs）和胞间CO2浓度（Ci）均受到一定抑制，但除胁迫中期（9月）金丝草光合速率受到明显的抑制外，其他光合特性指标在不同胁迫时期抑制作用均不明显；
（9）同质和异质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）均先减小后增大，在中午12时达最大，然后逐渐减小，呈正态分布；胞间CO2浓度（Ci）则表现为先减小后增大，在中午12时最小。
（10）同质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片可变荧光Fv和PSⅡ最大光化学效率均先减小后增大，PSⅡ潜在活性则先增大后减小；不同Pb胁迫浓度，不同胁迫时间，金丝草叶片PSⅡ最大光化学效率和PSⅡ潜在活性均大于无Pb对照；Pb胁迫对金丝草叶片荧光特性有一定促进作用。
（11）同质和异质Pb胁迫条件下，随胁迫时间的增加，金丝草叶片SPAD值呈逐渐减小的变化规律。随Pb胁迫浓度的增大，金丝草叶片SPAD值呈“W”型的变化规律，但不同Pb胁迫处理金丝草叶片SPAD值均与对照无显著差异（P＜0.05）。Pb胁迫对金丝草叶片SPAD值抑制不明显。
（12）轻度Pb胁迫（150mg·kg~(-1)）对金丝草叶片叶绿素a、叶绿素b和叶绿素总量均有一定促进作用，高浓度Pb胁迫对叶绿素b有一定促进作用；随胁迫浓度和时间的增加，Pb胁迫对金丝草叶片叶绿素的抑制作用逐渐增大。
（13）同质和异质Pb胁迫条件下，随Pb浓度的增大，金丝草叶片POD、SOD和MDA含量均逐渐增大，金丝草叶片POD、SOD和MDA含量均远大于百喜草，而CAT含量则表现为百喜草大于金丝草。Pb胁迫条件下，金丝草通过提高POD和SOD活性，增大膜脂化反应，以适应Pb胁迫环境，这是金丝草耐Pb的重要生理机制之一；
（14）同质Pb胁迫条件下，金丝草根系中含的主要有机酸为草酸、柠檬酸和苹果酸，且随Pb胁迫浓度的增大表现出逐渐增大的趋势；金丝草地上部分含的主要有机酸为草酸；异质Pb胁迫条件下，金丝草根系和地上部分低分子有机酸主要以草酸、丙二酸、苹果酸和柠檬酸为主，还含有少量反丁烯二酸，其中草酸含量最高，其次为苹果酸和柠檬酸。金丝草主要通过草酸的螯合作用，达到对Pb胁迫的解毒。
（15）重度Pb胁迫条件下，金丝草地上部分Pb全量显著大于其他处理及无Pb对照（P＜0.05），且含量大于1000mg·kg~(-1)，达到Pb超富集植物地上部分Pb富集量的标准；转移系数随Pb胁迫浓度的增大，在胁迫浓度2500mg·kg~(-1)处理为1.153＞1，超过Pb超富集植物转移系数大于1的标准；金丝草对Pb胁迫有较强耐性，而且可将大量土壤中Pb转移到地上部分，达到修复土壤Pb污染的目的；金丝草具有强的转运土壤中Pb的能力，然后通过地上部分的凋落将Pb移出，这是金丝草耐Pb特性的重要机制之一；
（16）同质和异质Pb胁迫条件下，不同Pb胁迫处理，金丝草地上部分和根系中Pb均主要以盐酸提取态存在，乙醇提取态和残渣态在低浓度和高浓度Pb胁迫处理间存在一定差异。同质Pb胁迫条件下，金丝草地上部分盐酸提取态Pb占79.04%-94.37%，根系占70.61%-85.92；异质Pb胁迫条件下，金丝草体内残渣态Pb含量所占比例增加，乙醇提取态所占比例减小；Pb胁迫条件下，金丝草体内Pb的迁移能力降低，从而减轻Pb的毒害作用。
（17）同质Pb胁迫条件下，随Pb浓度的增大，金丝草凋落体中乙醇提取态和盐酸提取态Pb含量及总Pb含量均先增大后减小，残渣态Pb含量则逐渐增大；异质Pb胁迫条件下，随Pb浓度的增大，金丝草凋落体内乙醇提取态Pb含量先增大后减小，盐酸提取态Pb含量逐渐增大，残渣态出现增大减小的波动；金丝草可通过植物组织的凋亡过程，将体内Pb移出，以达到自我解毒的目的。
综上所述，Pb超富集植物金丝草对Pb胁迫的响应表现为多途径的适应机制：首先，在高浓度Pb胁迫条件下金丝草可通过根的快速伸长，寻觅无Pb斑块，避让Pb胁迫，在无法避让时则对Pb产生“滞吸”作用。其次，可通过加快光合速率（Pn）和气孔导度（Gs），降低蒸腾速率（Tr），促进叶绿素合成、提高可变荧光Fv、PSⅡ最大光化学效率和PSⅡ潜在活性，加快金丝草抗逆性物质的合成，提高地上部分生物量分配，将土壤中的Pb转移至地上部分，然后通过加快地上部分的萌蘖更新，借助凋落将Pb移至体外，实现自身解毒；最后，金丝草还可通过提高体内POD和SOD活性，增大膜脂化反应，加快体内草酸、柠檬酸和苹果酸的分泌，螯合进入体内的Pb，将Pb转化为难溶态，减轻Pb胁迫对植物的伤害，以适应Pb胁迫环境。
Soil heavy mental pollution has become one of the current hot topics in environmentalscientific community. Pb pollution in environmental pollution of heavy metal is most prominent.Soil Pb pollution can enter into human body through the food chain quickly, this affectmetabolism of human body seriously. Besides the process which human body release Pb by itselfis very slow, the damage to organs in the body is irreversible. Therefore, Pb pollution treatmenthas become an urgent subject currently. Traditional method of treatment to heavy metal pollutionin soil mainly use mixing of soil, leaching method, chemical modifiers ect. Such physical andchemical methods which are not only expensive and cannot apply in small areas but also causedsecond pollution, such methods cannot solve the Pb pollution in soil fundamentally. In recentyears, people have found the bioconcentration ability of some plants to heavy metals. It is a highefficiency, environmental protection and cost control measures to use such plants asphytoremediation of heavy metal pollution. This treatment measure has a very broad applicationprospects.
The prerequisite to the application of phytoremediation to heavy metal contaminated soilswas the discovery of heavy metal hyperaccumulators. Pb is not easy be absorbed by plant for thehigher electronegativity of Pb, and easy form a covalent bond with the soil organic matter andFe-Mn oxide. Currently rare hyperaccumulators were found at home and abroad. Pbhyperaccumulator plant—Pogonatherum crinitum was found by our research teem previous forthe first time in China, which can grow normally in the lead-zinc mining area of high content ofPb up to17496mg·kg~(-1). This plant has strong tolerance and accumulation ability of Pb, and overof Pb hyperaccumulator standard. But currently it is still not clear of the tolerance andaccumulation mechanism of Pogonatherum crinitum to Pb, especially not so clear howPogonatherum crinitum react by physiological ecology characteristics under high Pbconcentration. These problems limit the application of Pogonatherum crinitum in the remediationof Pb polluted soil.
Based on these researches and studies, according to the principle and method of plantresistance physiology, toxicology, root biology, taking Pb hyperaccumulator Pogonatherumcrinitum which was first found by our research group as the research object, meanwhile selecting Paspalum natatu which is included in the same grass family as a control, simulation Pb stress testin the lab was taken, designed homogeneity and heterogeneity Pb stress test with manyinstruments including BTC root dynamic monitor, root image analyzer, Lci portablephotosynthetic apparatus, atomic absorption spectrophotometer, ect.Morphology and physiologyreaction was tested under different Pb stress condition, accumulation and transport capacity of Pbby Pogonatherum crinitum and Paspalum natatu was compared, the possible physiologicalecology way of Pogonatherum crinitum adopt to enrionment was revealed. This can also providescientific basis to clarify the hyperaccumulator plants resistant to Pb and Pb rich mechanism. Ithas important theoretical and practical significance for accelerating the repair of soil Pb pollutionand discover potential rich Pb characteristics of Pb Hyperaccumulator. The main results are asfollows:
(1) Low concentration of Pb stress (50mg·L~(-1)and150mg·L~(-1)) had positive effect onPogonatherum crinitum seeds germination potential, germination rate, germination index andvigor index. But with the increase of Pb stress concentration, the germination of the seed indexwas gradually decreased. Pogonatherum crinitum still had certain germination ability under Pbstress concentration of800mg·L~(-1). The effect on the shoot, root and seedling growth inhibition ofPb stress of Pogonatherum crinitum was not obvious.
(2) Homogeneous Pb stress had no significant inhibitory effect on the growth of Pogonatherumcrinitum. Seedings of Pogonatherum crinitum rapid growth in July and August, the growth inOctober was smallest. Pogonatherum crinitum could increase root biomass allocation adapt to Pbstress environment.Pb stress could accelerate the sprout updation of Pogonatherum crinitum, thisprobably was one mechanism of Pogonatherum crinitum adapt to high concentration.
(3) Pogonatherum crinitum seedling height, sprout tiller had some inhibitory effect at early stageof heterogeneous stress (30d), but with the time increasing of Pb stress, inhibition is less and lessunder heterogeneous Pb stress condition. Under heterogeneous Pb stress condition Pogonatherumcrinitum seedling height increase to the maximum in July, minimum in October, seedling height inJune and August are same. Biomass allocate more to root part under low Pb concentration stresscondition, but with the increase of Pb concentration, biomass allocation to shoot more, whichmore Pb could transfer to shoot.
(4) Pb stress had inhibitory effect on root length and surface area of Pogonatherum crinitum underHomogeneous Pb stress condition. Along with the increase of Pb concentration, total root lengthand surface area of the root were increased first and then decreased. Root length grows up tomaximum of621.05cm at Pb stress concentration500mg·kg~(-1)treatment, root surface area growsup to a maximum of20.29cm2at Pb stress concentration2500mg·kg~(-1)treatment. Pb stress had noobvious inhibition on the root average diameter and volume of Pogonatherum crinitum.Pogonatherum crinitum could avoid Pb stress by root growth to adapt to the higly Pbconcentration stress environment.
(5) Total root length and surface area of Pogonatherum crinitum on left compartments was greaterthan right compartments with Pb stress concentration increased under heterogeneous Pb stresscondition. Root length of Paspalum natatu in left compartments without Pb stress under differentPb stress condition were greater than Pogonatherum crinitum, but root length of Pogonatherumcrinitum in right compartments were greater than Paspalum natatu. Along with the increase of Pbconcentration, the root surface area and average diameter of Pogonatherum crinitum increasedunder higly Pb concentration condition.
(6) Root could be observated in the treatment of Pb concentration of150mg·kg~(-1)and2500mg·kg~(-1)at homogeneity of Pb stress conditions by BTC dynamic monitoring system, theprobability of root growing into Pb stress plaque was28.57%. In Higly Pb concentration (2500mgkg~(-1)) plaque, root surface area and root volume increased more than the low Pb concentration(150mg kg~(-1)) plaque from August to September, the the changes of root length and diameter wereantithetical. Root could be observated at Pb concentration of1000mg·kg~(-1)treatment. Theprobability of root growing into Pb stress plaque was14.28%under heterogeneous Pb stresscondition in the season of September and October, this means Pogonatherum crinitum hasdcertain avoidance of Pb stress.
(7) Photosynthesis rate (Pn) and stomatal conductance (Gs) of Pogonatherum crinitum weresignificant inhibited in medium test term (September) under homogeneous Pb stress conditions,but less inhibitory effect in Pb stress test initial stage and last phase, and quickly increased atinitial stage of Pb concentration of150mg·kg~(-1)and1500mg·kg~(-1)treatments. Photosynthesis rate(Pn) and stomatal conductance (Gs) of Paspalum natatu were smaller than control at different testtime. Intercellular CO2concentration (Ci) of Pogonatherum crinitum had no significant difference with control at different stress time under homogeneous Pb stress conditions.Transpiration rate (Tr)of Pogonatherum crinitum decreased. Pogonatherum crinitum could reduce the transpiration inorder to ensure its growth.
(8)Various photosynthetic characteristics of Pogonatherum crinitum were inhibited underheterogeneous Pb stress conditions, except photosynthetic rate of Pogonatherum crinitum wasinhibited significantly in stress medium term(September), other stress times inhibitory effect werenot obvious.
(9) Leaf photosynthesis rate (Pn), stomatal conductance (Gs) and transpiration rate(Tr) ofPogonatherum crinitum were first decreased and then increased, reached a maximum value at12:00, then decreased gradually, while the intercellular CO2concentration(Ci) first decreased andthen increased, reached a minimum value at12:00under homogeneous and heterogeneous Pbstress condition.
(10) With increased of stress time, Pogonatherum crinitum leaf variable fluorescence Fv and themaximal photochemical efficiency of PSⅡ first decreased then increased, PSII potential activityincreased first and then decreased under homogeneous Pb stress:. In different heterogeneous Pbstress concentration and different stress time, PSⅡmaximal photochemical efficiency and PSⅡpotential activity were more than control which without Pb stress. This means that Pb stresspromoted the fluorescence properties of Pogonatherum crinitum.
(11) Leaf green degree of Pogonatherum crinitum decreased substantially with the increase ofstress time under homogeneous and heterogeneous Pb stress conditions. With the increase of Pbstress concentration, leaf green degree of Pogonatherum crinitum was W–shape changed, butdifferent Pb stress treatments had no significant difference with the control (P <0.05). Pb stresshad a certain inhibitory effect on leaf green degree.
(12) Pb stress had a certain inhibitory effect on the chlorophyll content of Pogonatherum crinitum,except lower Pb concentration of150mg·kg~(-1)treament could promote Chlorophyll a, chlorophyllb, total chlorophyll and chlorophyll a/b of Pogonatherum crinitum under homogeneous Pb stress.With the increase of Pb stress concentration the inhibition increased.
(13) The content of POD、SOD and MDA in Pogonatherum crinitum leaf is more than Paspalumnatatu while CAT in Pogonatherum crinitum leaf is less than Paspalum natatu both underhomogeneous and heterogeneous Pb stress conditions. This indicates that Pogonatherum crinitum under Pb stress condition increase SOD and POD activity to increase membrane lipid reaction toadapt Pb stress environment, this is one of the physiological mechanism of Pogonatherumcrinitum resistant to Pb sress.
(14) Main organic acids in root part of Pogonatherum crinitum include Oxalic acid, citric acid andmalic acid, and showed gradually increased trend along with increased of Pb stress concentrationunder homogeneous Pb stress conditions. Under heterogeneous Pb stress conditions, root andshoot in Pogonatherum crinitum had low molecular organic acid mainly include oxalic acid,malonic acid, malic acid and citric acid, the oxalic acid content is the highest, followed by malicacid and citric acid. Pogonatherum crinitum can reach to detoxification of Pb stress mainlythrough the effect of oxalic acid chelate.
(15) Total Pb content in shoot under higher Pb stress condition significantly greater than othertreatments and control, and Pb content in shoot and Pb transfer index were exceed the standard ofPb hyperaccumulation. Pogonatherum crinitum has strong transport of soil Pb, and based on thepart of the litter make Pb out of body, this may be one of the mechanisms of Pogonatherumcrinitum resistance Pb stress.
(16) The form of Pb in shoot and root of Pogonatherum crinitum under different Pb stresstreatments in both homogeneous and heterogeneous Pb stress condition were mainly HClextraction, ethanol extraction and residual Pb existed certain difference. HCl extraction Pbaccounted for70.61%-85.92in root and79.04%-94.37%in shoot under homogeneous Pb stresscondition.The residual Pb content in plant increased but ethanol extraction Pb dcreased, whichshows that Pb in Pogonatherum crinitum could component chelating, lower ability of migration,thereby reducing the toxicity of Pb.
(17)Ethanol and HCl extractable Pb content and total Pb content increased first and thendecreased, the residue Pb content increased with the increase of Pb concentration underhomogeneous Pb stress condition. Ethanol extractable Pb content increased first then decreased,HCl extractable Pb content increased with the increase of Pb concentration under heterogeneousPb stress condition. Total Pb and different form Pb content in apoptosis body of Pogonatherumcrinitum were higher than Paspalum natatu, which drawed the results Pogonatherum crinitumcould remove Pb out of body through the apoptosis of plant tissue, in order to detoxification.
In summary response mechanism of Pb hyperaccumulator Pogonatherum crinitum under Pb stress mainly include: firstly, Pogonatherum crinitum through the rapid elongation of root, find noPb patch, to avoid the Pb stress, so as to adapt to the high Pb concentration environment, but rootwill absorb Pb from soil after a period when can not avoid Pb stress. Then Pogonatherum crinitumcan increase photosynthetic rate (Pn) and stomatal conductance (Gs), decrease the transpirationrate (Tr), promote chlorophyll synthesis, improve the variable fluorescence Fv, the maximalphotochemical efficiency of PSⅡ and PSⅡ potential activity, increase synthesis of biomass,improve root biomass allocation adaptive Pb stress environment under Pb concentrationconditions, by improving the biomass distribution of shoot, transfer Pb in soil to overground part,then accelerate sprouting update rate, through fallen litter take Pb out off body, realize their owndetoxification under High concentration Pb stress. In addition, Pogonatherum crinitum canincrease POD and SOD activity, increased membrane lipid peroxidation reaction, by increasingsecrete more citric acid and malic acid, chelation of Pb in body, transform Pb into insoluble state,to achieve detoxification of Pb stress.
引文
[1] Ameh E G, Akpah F A. Heavy metal pollution indexing and multivariate statistical evaluation ofhydrogeochemistry of River PovPov in Itakpe Iron-Ore mining area, Kogi State, Nigeria[J]. Advances inApplied Science Research,2011,2(1):33-46
[2]李瑞琴，于安芬，白滨.甘肃中部高原露地菜田土壤重金属污染及潜在生态风险分析[J].农业环境科学学报，2013，32(1)：103-110.
[3] Bissenbaev A K, Ishchenko A A, Taipakova S M, et al. Saparbaev Presence of base excision repair enzymesin the wheat aleurone and their activation in cells undergoing programmed cell death [J]. Plant Physiologyand Biochemistry,2011,49(10):1155-1164.
[4]唐文浩，岳平，陈恒宇．海南岛砖红壤中铅、镉的化学形态与转化[J]．中国生态农业学报2009，17(1)：145-149．
[5] Tanhan P, Kruatrachue M, Pokethitiyook P. Uptake and accumulation of cadmium, lead and zinc by Siamweed（Chromolaena odorata L. King&Robinson）[J]. Chemosphere,2007,68（2）:323-329.
[6]王学礼，常青山，侯晓龙，等．三名铅锌矿区植物对重金属的富集特征[J]．生态环境学报，2010，19（1）：108-112．
[7]吴龙华，张长波，章海波，等．铅稳定同位素在土壤污染物来源识别中的应用[J]．环境科学，2009，30（1）：227-230．
[8]闵焕，祖艳群，李元．Pb胁迫对圆叶无心菜（Arenaria rotumdifolia Bieberstein）生长和生理特征的影响[J]．农业环境科学学报，2010，29（B03）：15-19．
[9]汤叶涛，吴好都，仇荣亮，等．滇苦菜（Picris divaricata Vant.）对锌的吸收和富集特性[J]．生态学报，2009，29（4）：1823-1831．
[10]钟珍梅，王义祥，杨冬雪，等．4种植物对铅、镉和砷污染土壤的修复作用研究[J]．农业环境科学学报，2010，29（增刊）：123-126．
[11] He Q X, Huang Xiao C, Chen Z L. Influence of organic acids, complexing agents and heavy metals on thebioleaching of iron from kaolin using Fe(III)-reducing bacteria [J]. Applied Clay Science,2011,51(4):478-483.
[12] Cho Y S, Bolick J A, Butcher D J. Phytoremediation of lead with green onions (Allium fistulosum) and uptakeof arsenic compounds by moonlight ferns (Pteris cretica cv Mayii)[J], Microchemical Journal,2009,91(1):6-8.
[13]陈红琳，张世熔，李婷，等．汉源铅锌矿区植物对Pb和Zn的积累及耐性研究[J]．农业环境科学学报，2007，26（2）：107-111．
[14]赵磊．白音诺尔铅锌矿铅超富集植物筛选及其耐性研究[D]．呼和浩特：内蒙古农业大学，2009．
[15]杨远祥，邹开贵，朱雪梅，等．铅锌胁迫对铅超富集植物小鳞苔草生理代谢特性的影响[J]．陕西农业科学，2009，（6）：83-85．
[16]汤叶涛，仇荣亮，曾晓雯，等．一种新的多金属超富集植物——圆锥南芥（Arabis paniculata L.）[J]．中山大学学报（自然科学版），2005，44（4）：135-136．
[17]侯晓龙，常青山，刘国锋，等． Ｐｂ超富集植物金丝草（Pogonatherum crinitum）、柳叶箬（Lsachneglobosa）[J].环境工程学报，2012，6（3）：989-994．
[18]侯晓龙，陈加松，刘爱琴，等． Pb胁迫对金丝草和柳叶箬生长及富Pb特征的影响[J]．福建农林大学学报(自然科学版)，2012，41（3）：286-290．
[19]常青山．重金属超富集植物的筛选与螯合吸附研究[D]．福州：福建农林大学，2005．
[20] Visioli G, Marmiroli N The proteomics of heavy metal hyperaccumulation by plants [J]. Journal ofProteomics,2013,79(2）:133-145.
[21]何闪英，高永杰，申屠佳丽，等．铜和模拟酸雨复合胁迫对酸模铜富集、生长及抗氧化酶系统的影响[J]．应用生态学报，2011，22（2）：481-487．
[22] Bini C, Wahsha M, Fontana S, et al. Effects of heavy metals on morphological characteristics of Taraxacumofficinale Web growing on mine soils in NE Italy[J]. Journal of Geochemical Exploration,2012,123(12):101-108.
[23] Li T Q, Yang X E, Lu L L, et al. Effects of zinc and cadmium interactions on root morphology and metaltranslocation in a hyperaccumulating species under hydroponic conditions[J].Journal of Hazardous Materials,2009,169(1–3):734-741.
[24]马敏，龚惠红，邓泓.重金属对8种园林植物种子萌发及幼苗生长的影响[J].中国农学通报，2012，28(22):206-211.
[25]杨颍丽，王文瑞，尤佳，等.Cd2+胁迫对小麦种子萌发、幼苗生长及生理生化特性的影响[J].西北师范大学学报，2012，48（3）：88-94.
[26黄铭洪，束文圣，栾天罡，等．环境污染与生态恢复[M]．北京，科学出版社，2004，118-132．
[27]蔡佩英，刘爱琴，侯晓龙．9种水生植物对模拟污水中氮、磷的生物净化效果[J].福建农林大学学报（自然科学版），2010，39（3）：313-318．
[28] Marin A R,Masscheleyn P H, Patrick W H. Soil redox-pH stability of arsenic species and its influence onarsenic uptake by rice[J]. Plant and Soil,2004,152(2):245-253.
[29]田晓锋，魏虹，贾中民，等．重金属镉(Cd2+)对梧桐幼苗根生长及根系形态的影响[J]．西南师范大学学报(自然科学版)，2008，33（2）：93-98．
[30]贾中民，魏虹，孙晓灿，等．秋华柳和枫杨幼苗对镉的积累和耐受性[J]．生态学报，2011，31（1）：107-114．
[31]Tahar G, Issam N, Ines S, etal. Cadmium effects on growth and mineral nutrition of two ha1ophytes:SesuviumPortulacastrum and Mesembryanthemum crystallinu[J]. Journalof plant Physiology,2005,(162):133-140.
[32]刘灵，廖红，王秀荣，等．磷有效性对大豆菌根侵染的调控及其与根构型、磷效率的关系[J]．应用生态学报，2008，19（3）：564-568．
[33] Kiswara W, Behnke N, Van Avesaath P, et al. Root architecture of six tropical seagrass species, growing inthree contrasting habitats in Indonesian waters[J]. Aquatic botany,2009,90(3):235-245.
[34] Moradia A B, Conesab H M, Robinsonb B H, et al. Root responses to soil Ni heterogeneity in ahyperaccumulator and a non-accumulator species [J]. Environmental Pollution,2009,157(8):2189-2196.
[35] James J J, Mangold J M, Sheley R L, et al. Root plasticity of native and invasive Great Basin species inresponse to soil nitrogen heterogeneity[J].Plant Ecological,2009,202:211-220.
[36] Estrella G N, Mendoza C D, Moreno S R, et al. The Pb-hyperaccumulator aquatic fern Salvinia minimaBaker, responds to Pb(2+) by increasing phytochelatins via changes in SmPCS expression and inphytochelatin synthase activity [J]. Aquat Toxicol,2009,91(4):320-328.
[37]闫研，李建平，张学洪．超富集植物李氏禾对铬诱导的氧化胁迫响应[J]．生态环境，2008，17（4）：1476-1482．
[38] Hasanuzzaman M, Hossain M A, Fujiat M. Physiological and biochemical mechanisms of nitric oxideinduced abiotic stress tolerance in plants[J]. American Journal of Plant Physicology,2010,5(6):295-324.
[39] Engelen D L，Sharpe-Pedler R C，Moorhead K K. Effect of chelating agents and solubility ofcadmium complexes on uptake from soil by Brassica juncea[J].Chemosphere,2007,68：401-408.
[40] Donato R J, Roberts L A, Sanderson T, ea al. A rabidopsis Yellow Stripe-Like(YSL2): a metal regulatedgene encoding a plasma membrane transporter of nicotianamine-meal complexes[J]. Plant Journal,2004,39(3):403-414.
[41] Nehnevajova E, Lyubenova L, Herzig R, et al. Metal accumulation and response of antioxidant enzymes inseedlings and adult sunflower mutants with improved metal removal traits on a metal-contaminated soil[J].Environmental and Experimental Botany,2012,76(2):39-48.
[42] Anjum N A, Ahmad I, Mohmood I, et al. Modulation of glutathione and its related enzymes in plants’responses to toxic metals and metalloids[J]. Environmental and Experimental Botany,2012,75(1):307-324.
[43] Zhang Y, Zheng G H, Liu P, et al. Morohological and physiologicalresponses of root tip cells to Fe2+tocicityin rice[J]. ActaPhysiologiae Plantarum,2011,33(3):683-689.
[44]赵钢，邹亮，彭镰心，等.铅胁迫对苦荞生理特性的影响[J].江苏农业科学，2012,40（7）：98-100.
[45]朱启红，夏红霞.铅胁迫对蜈蚣草抗氧化酶系统和叶绿素含量的影响[J].贵州农业科学，2012,40（4）：56-58.
[46]蒋和平，郑青松，朱明，等.条浒苔和缘管浒苔对镉胁迫的生理响应比较[J].生态学报，2011,31（16）：4525-4533.
[47]高伟，魏虹，贾中民，等.香根草对镉胁迫的光合响应[J].西南师范大学学报，2012,37（10）：59-64.
[48]柴民伟，刘福春，曹迪，等. Pb对互花米草的生理特性和Pb在体内积累的影响[J].南开大学学报：自然科学版，2011，44（6）：33-40.
[49] Ingelmo F, José Molina M, Desamparados Soriano M, et al. Influence of organic matter transformations onthe bioavailability of heavy metals in a sludge based compost[J]. Journal of Environmental Management,2012,95(3):104-109.
[50] Chaumont A, Nickmilder M, Dumont X, et al. Associations between proteins and heavy metals in urine at lowenvironmental exposures: Evidence of reverse causality [J]. Toxicology Letters,2012,210(3):345-352.
[51] Rajkumar M, Sandhya S. Prasad M N V, et al. Perspectives of plant-associated microbes in heavy metalphytoremediation[J]. Biotechnology Advances,2012,30(6):1562-1574.
[52] GunNam N, Salt D E. The role of sulfur assimilation and sulfur-containing compounds in trae elementhomeostasis in plants[J]. Environmental and Experimental Botany,2011,72(1):8-25.
[53] Bennett L E，Burkhead J L，Kerry L H， et a1． Pilon-smits analysis of transgenic Indian mustard plants forphytoremediation of metal-contaminated mine tailings[J]．Journal of Environmental Quality，2003，32：432-440.
[54] Huang J W, Cunningham S D. Lead phytoextraction: species variation in lead uptake and translocation [J].New Phytologist,1996,134:75-84.
[55] Kanwar M K, Bhardwaj R, Arora P, Chowdhary S P, et al. Plant steroid hormones produced under Ni stressare involved in the regulation of metal uptake and oxidative stress in Brassica juncea L.[J]. Chemosphere,2012,86(1):41-49.
[56] Sun R L，Zhou Q X，Jin C C．Cadmium accumulation in telation to organic acids in leaves of Solanumnigrum L.as a newly found cadmium hyperaccumulator[J]．Plant and soil，2006，285(1)：125-134．
[57] Jeong S, Moon H S, Nam K, et al. Application of phosphate-solubilizing bacteria for enhancingbioavailability and phytoextraction of cadmium (Cd) from polluted soil [J]. Chemosphere,2012,88(2):204-210.
[58]李光辉，杨霞，徐加宽，等．不同湿地植物的根系酸化作用与重金属吸收[J]．生态环境学报，2009，18（1）：97-100．
[59] Nedelkoska T V, Doran P M. Hyperaccumulation of cadmium by hairy roots of Thlaspi caerulescens[J].Biotechnology and bioengineering,2000,67(5):607-615.
[60] Wojcik M, Vangronsveld J, Dhaen J, et al. Cadmiumtolerance in Thlaspi caerulescens[J]. Environmental andExperimental Botany,2005,53(2):163-171.
[61] Wang P, Zhou D M, Kinraide T B, et al. Cell menbrane surface potential plays a dominant role in thephytotoxicity of copper and arsenate[J]. Plant Physiology,2008,148,2134-2143.
[62] Li W X, Chen T B, Huang Z C, et a. Effect of arsenic on chlorop last ultrastructure and calcium distribution inarsenic hyperaccumulator Pterisvittata L[J]. Chemosphere,2006,62:803-809.
[63]包姣，韦惠琴，赵秀兰．低分子量有机酸强化烟草修复镉污染土壤的适用性研究[J]．水土保持学报，2012,26（2）：265-270．
[64]乔冬梅，樊向阳，樊涛，等．Pb2+胁迫下黑麦草对外源有机酸的响应机制[J]．水土保持学报，2012,26（2）：261-264．
[65] Magdziak Z, Kozlowska M, Kaczmarek Z, et al. Influence of Ca/Mg ratio on phytoextraction properties ofSalix viminalis. II. Secretion of low molecular weight organic acids to the rhizosphere[J]. Ecotoxicology andEnvironmental Safety,2011,74(1):33-40.
[66] Kramer U，Cotter-Howells J D，Charnock J M，et al．Free histidine as a metal chelaor in plants[J]．Nature，1996，379：635-638．
[67] Zhang Y X，Chai T Y． Research advances on the mechanisms of heavy metal tolerance in plants[J]．ActaBotanica sinca，1999，41(5)：453-457．
[68]李华，黄建国，王明霞.锰对外生菌根真菌生长、养分吸收及有机酸分泌的影响[J].背景林业大学学报，2012,34（3）：76-80.
[69]唐宇庭，黄佳玉，王维生，等.低分子有机酸对油菜吸收Cd和Zn的影响[J].广西师范大学学报：自然科学版，2012,30（2）：127-131.
[70] Bendjeffal H, Guerfi K, Bouhedja Y, et al. Immobilization of complexes of some heavy metals with a2-(4-pyridylazo)-resorcinol “PAR” on Algerian hydrothermal clay[J]. Physics Procedia,2009,2(3):889-897.
[71] Ko odyńska D. Green complexing agent—EDDS in removal of heavy metal ions on strongly basic anionexchangers[J]. Desalination,2011,280(1-3):44-57.
[72] Margoshes M, Vallee B L. Acadmium prorein from equine kidney corter[J]. Journal of the Americanchemical society,1957,79:4813-4814.
[73] Heiss S, Wachter A, Bogs J, et al. Phytochelatin synthase（PC）protein is induced in Brassica juncea leavesafter prolonged Cd exposure[J].Experimental Botany,2003,54(389):1833-1839.
[74] Janouskova M, Pavlikova D, Macek T, et al. Arbuscular mycorrhiza decreases cadmium phytoextraction bytransgenic tobacco with inserted metallothionein[J]. Plant and Soil,2005,272(1):29-40.
[75]王超，王丽娅，孙琴，等.低浓度Cd胁迫下2种水生植物体内植物络合素的响应[J].四川大学学报，2008，40（6）：87-94.
[76] Battelli R, Lombardi L, Rogers H J, et al. Changes in ultrastructure, protease and caspase-like activitiesduring flower senescence in Lilium longiflorum[J]. Plant Science,2011,180(5):716-725.
[77] Alden K P, Dhondt-Cordelier S, McDonald K L, et al. Sphingolipid long chain base phosphates can regulateapoptotic-like programmed cell death in plants[J] Biochemical and Biophysical Research Communications,2011,410(3):574-580.
[78] Vartapetian AB, Tuzhikov AI, Chichkova NV, Taliansky M, Wolpert TJ. A plant alternative to animalcaspasees: subtilisin-like proteases. Cell Death Differ,2011,18(8):1289-1297.
[79] Jiménez C, Capasso J M, Edelstein C L,et al. Different ways to die: cell death modes of the unicellularchlorophyte Dunaliella viridis exposed to various environmental stresses are mediated by the caspase-likeactivity DEVDase[J]. Journal of Experimental Botany,2009,60(3):815–828.
[80] Wangeline A L，Burkhead J L，Hale K L，et a1．Over pression of ATP sulfurylase in Indian mustard：effectson tolerance and accumulation of twelve metals[J]．Journal of Environmental Quality，2004，33(1)：54-57．
[81] Maxted A P, Black C R, West H M, et al. Phytoextraction ofcadmium and zinc from arable soils amended withsewage sludge using Thlaspi caerulescens: development of a predictive model[J]. Environmental Pollution,2007,150(3):363-372.
[82] Leitenmaier Barbara, Witt A, Witzke A, et al. Biochemical and biophysical characterisation yields insightsinto the mechanism of a Cd/Zn transporting ATPase purified from the hyperaccumulator plant Thlaspicaerulescens[J]. Biochimica et Biophysica Acta-Biomembranes,2011,1808(10):2591-2599.
[83]王爱霞，方炎明.空气重金属元素在悬铃木叶中的亚细胞分布及其区隔化效应[J].西北植物学报，2011，31（3）：479-485.
[84]王芳，丁杉，张春华，等.不同镉耐性水稻非蛋白巯基及镉的亚细胞和分子分布[J].农业环境科学学报，2010，29（4）：625-629.
[85]魏树和，杨传杰，周启星，等.三野鬼针草等7种常见菊科杂草植物对重金属的超富集特征[J].环境科学，2008，29（10）：2912-2918.
[86]张玉秀，于飞，张媛雅，等.植物对重金属镉的吸收转运和积累机制[J].中国生态农业学报，2008，16(5)：1317-1321.
[87]周守标，王春景，杨海军，等.菰和菖蒲对重金属的胁迫反应及其富集能力[J].生态学报，2007，27（1）：281-287.
[88]鲁如坤．土壤农业化学分析方法［M］．北京：中国农业科技出版社，2000．
[89]王朝文．不同温度对总状绿绒蒿种子萌发的影响［J］．种子，2009，28(2)：25-27．
[90]朱广廉,钟海文,张爱琴.植物生理实验[M].北京:北京大学出版社,1995.
[91]张志良.植物生理学实验指导[M](第二版).北京:高等教育出版社.1990:154-155.
[92]李合生.植物生理生化实验原理和技术[M].北京:高等教育出版社,2000
[93]毛达如.植物营养研究方法[M].北京:中国农业大学出版社,2005.
[94]宋金凤，崔晓阳，刘永.毛细管气相色谱法测定森林凋落物中的有机酸[J].林业科学，2004，40（4）：185-188.
[95]吴慧梅，李非里，牟华倩，等.两步连续提取法测定植物中重金属的形态[J].环境科学与技术，2012，35(7):133-137.
[96]吕静霞，张雅莉.铅胁迫对小麦种子萌发及幼苗生长的影响[J].种子，2012，31（1）：100-103.
[97] Deborah L A,Wesley M J. Proton and copper absorption to maize and soybean root cell walls[J].PlantPhysiology,1989,89:823-832.
[98] Branquinho C,Brown D H,Catarino F. The celluar location of Cu in lichens and its effects on membraneinlegrity and chlorophyII fluorescence[J]. Environmental and Experimental Botany,1997,38(2):165-179.
[99]唐为萍，陈树思，陈琳.铅处理对含羞草种子萌发及幼苗生长的影响[J].湖北农业科学，2009，48（11）：2777-2779.
[100]叶利民，樊兰紫，王爱斌.铅胁迫对不同品种小白菜种子萌发的影响[J].中国野生植物资源，2011，30（5）：51-53.
[101]康丽娜，吴福忠，何振华，等. Pb胁迫对欧美杂交杨（Populus deltoides×Populus nigra）生物量分配格局及其Pb富集特性的影响[J].农业环境科学学报，2012，31（3）：484-490.
[102] Jusselme M D, Poly F, Edouard Mi, Effect of earthworms on plant Lantana camara Pb-uptake and onbacterial communities in root-adhering soil [J]. Science of The Total Environment,2012,416(1):200-207.
[103] Chenery S R, Izquierdo M, Marzouk E, et al. Soil–plant interactions and the uptake of Pb at abandonedmining sites in the Rookhope catchment of the N. Pennines, UK—A Pb isotope study [J]. Science of TheTotal Environment,2012,433(9):547-560.
[104]林晓倩，张健，杨万勤，等.3种土壤类型下铅胁迫对巨桉幼苗的影响[J].林业科学，2013，49（1）：1-6.
[105]王宁，南忠仁，王胜利，等.Cd/Pb胁迫下油菜中重金属的分布、富集及迁移特征[J].兰州大学学报（自然科学版），2012，48（3）：18-22.
[106]胡方洁，张健，杨万勤，等.Pb胁迫对红椿（Toona ciliata Roem）生长发育及Pb富集特性的影响[J].农业环境科学学报，2013，31（2）：284-291.
[107]孟晓霞，龙巍，郑超，等.铅胁迫对西南山梗菜生长及逆境生理指标的影响[J].四川农业大学学报，2012，30（3）：336-341.
[108]陶玲，郭永春，李萍，等.铅胁迫对3种豆类作物生理特性的影响[J].中国农学通报，2012，28（33）：78-83.
[109] Gump B B, MacKenzie J A, Bendinskas K, et al. Low-level Pb and cardiovascular responses to acute stressin children: The role of cardiac autonomic regulation [J]. Neurotoxicology and Teratology,2011,33(2):212-219.
[110]夏红霞，朱启红，何超.黑麦草叶绿素荧光特性对Pb2+胁迫的响应[J].贵州农业科学，2012，40（12）：33-35.
[111]李清飞.麻疯树对铅胁迫的生理耐性研究[J].生态与农村环境学报,2012，28(1):72-76.
[112]刘慧芹，韩巨才，刘慧平，等.铅梯度胁迫对多年生黑麦草幼苗生理生化特性影响[J].草业学报.2012,21(6):57-63.
[113] Basic N, Salamin N, Keller C,et al. Cadmium hyperaccumulation and genetic differentiation of Thlaspicaerulescens populations[J].Biochemical Systematics and Ecology,2006,34(9):667-677.
[114] Maestri E, Marmiroli M, Visioli G, et al. Metal tolerance and hyperaccumulation: Costs and trade-offsbetween traits and environment[J].Environmental and Experimental Botany,2010,68(1):1-13.
[115]赵红芳，黄宝康.重金属胁迫下药用植物耐受及超富集的机制[J].药学实践杂志，2010,28（6）：406-467.
[116]麦维军，王颖，梁承邺，等.谷胱甘肽在植物抗逆中的作用[J].广西植物，2005,25（6）：570.
[117] Jose J, Giridhar R, Anas A,et al. Heavy metal pollution exerts reduction/adaptation in the diversity andenzyme expression profile of heterotrophic bacteria in Cochin estuary, India [J].Environmental Pollution,2011,159(10):2775-2780.
[118]李文学，陈同斌.超富集植物吸收富集重金属的生理和分子生物学机制[J].应用生态学报，2003,14（4）：627.
[119] Vollenweider P, Bernasconi P, Gautschi H, et al. Compartmentation of metals in foliage of Populus tremulagrown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles[J].EnvironmentalPollution,2011,159(1):337-347.
[120] Cang L, Zhou D M, Wang Q Y, et al. Impact of electrokinetic-assisted phytoremediation of heavy metalcontaminated soil on its physicochemical properties, enzymatic and microbial activities [J].ElectrochimicaActa,2012,86(30):41-48.
[121] Maestri E, Marmiroli M, Visioli G, et al. Metal tolerance and hyperaccumulation: Costs and trade-offsbetween traits and environment[J]. Environmental and Experimental Botany,2010,68(1):1-13.
[122] Kim S, Lim H, Lee I. Enhanced heavy metal phytoextraction by Echinochloa crus-galli using rootexudates[J]. Journal of Bioscience and Bioengineering,2010,109(1):47-50.
[123] Manzoor Q, Nadeem R, Iqbal M, et al. Organic acids pretreatment effect on Rosa bourbonia phyto-biomassfor removal of Pb(II) and Cu(II) from aqueous media[J]. Bioresource Technology,2013,132,446-452.
[124] He Q X, Huang X C, Chen Z L. Influence of organic acids, complexing agents and heavy metals on thebioleaching of iron from kaolin using Fe(III)-reducing bacteria[J]. Applied Clay Science,2011,51(4):478-483.
[125]吴双桃，吴晓芙，胡曰利，等.铅锌冶炼厂土壤污染及重金属富集植物研究[J].生态环境，2004,13（2）：156.
[126]王飞，胥焘，张晟，等. Pb、Cd单一及复合胁迫对桂花幼苗生理生化特性的影响[J].三峡环境与生态，2013,35（1）：3-7.
[127]王启明．铅、镉单一及复合胁迫对玉米幼苗生理生化特性的影响[Ｊ]．安徽农业科学，2006，34（10）：2036-2037．
[128]徐学华，黄大庄，王连芳，等．土壤铅、镉胁迫对红瑞木生长及生理生化特性的影响[J].水土保持学报，2009，23(1)：213-216．
[129] Phillips C J C, Mohamed M O, Chiy P C. Effects of duration of exposure to dietary lead on rumenmetabolism and the accumulation of heavy metals in sheep [J]. Small Ruminant Research,2011,100(2-3):113-121.
[130] Kerr J FR, Wyllie AH,Currie A R.Apoptosis:a basic biological phenomenon with wideranging implicationsin tissue kinetics. British Journal of Cancer,1972,26:239-257.
[131] Wouter G. van Doorn.Classes of programmed cell death in plants, compared to those in animals[J]. Journal ofExperimental botany,2011,62(14):4749-4761.
[132] Manzoor H, Chiltz A, Madani S, et al. Calcium signatures and signaling in cytosol and organelles of tobaccocells induced by plant defense elicitors[J]. CellCalcium,2012,51(6):434-444.
[133] Petrov V, Vermeirssen V, Clercq I D, et al. Identification of cis-regulatory elements specific for differenttypes of reactive oxygen species in Arabidopsis thaliana[J]. Gene,2012,499(1):52-60.
[134] Sergey Shabala.Commentary: Salinity and programmed cell death: unravelling mechanisms for ion specificsignalling, Journal of Experimental botany,2009,60(3):709-712.
[135] Reape T J, Molony E M. Programmed cell death in plants: distinguishing between different modes[J].Journal of Experimental botany,2008,59(3):435-444.
[136] Sobkowiak R, Gzyl J, Pawlak-Sprada S, et al. Nitric oxide implication in cadmium-induced programmed celldeath in roots and signaling response of yellow lupine plants[J]. Plant Physiology and Biochemistry,2012,58(9):124-134.
[137] Arasimowicz-Jelonek M, Floryszak-Wieczorek J, Deckert J, et al. Nitric oxide implication incadmium-induced programmed cell death in roots and signaling response of yellow lupine plants[J]. PlantPhysiology and Biochemistry,2012,58(9):124-134.
[138] Panda K K, Achary V M, Krishnaveni R. In vitro biosynthesis and genotoxicity bioassay of silvernanoparticles using plants[J]. Toxicology in Vitro,2011,25（5）：1097-1105.
[2]李瑞琴，于安芬，白滨.甘肃中部高原露地菜田土壤重金属污染及潜在生态风险分析[J].农业环境科学学报，2013，32(1)：103-110.
[3] Bissenbaev A K, Ishchenko A A, Taipakova S M, et al. Saparbaev Presence of base excision repair enzymesin the wheat aleurone and their activation in cells undergoing programmed cell death [J]. Plant Physiologyand Biochemistry,2011,49(10):1155-1164.
[4]唐文浩，岳平，陈恒宇．海南岛砖红壤中铅、镉的化学形态与转化[J]．中国生态农业学报2009，17(1)：145-149．
[5] Tanhan P, Kruatrachue M, Pokethitiyook P. Uptake and accumulation of cadmium, lead and zinc by Siamweed（Chromolaena odorata L. King&Robinson）[J]. Chemosphere,2007,68（2）:323-329.
[6]王学礼，常青山，侯晓龙，等．三名铅锌矿区植物对重金属的富集特征[J]．生态环境学报，2010，19（1）：108-112．
[7]吴龙华，张长波，章海波，等．铅稳定同位素在土壤污染物来源识别中的应用[J]．环境科学，2009，30（1）：227-230．
[8]闵焕，祖艳群，李元．Pb胁迫对圆叶无心菜（Arenaria rotumdifolia Bieberstein）生长和生理特征的影响[J]．农业环境科学学报，2010，29（B03）：15-19．
[9]汤叶涛，吴好都，仇荣亮，等．滇苦菜（Picris divaricata Vant.）对锌的吸收和富集特性[J]．生态学报，2009，29（4）：1823-1831．
[10]钟珍梅，王义祥，杨冬雪，等．4种植物对铅、镉和砷污染土壤的修复作用研究[J]．农业环境科学学报，2010，29（增刊）：123-126．
[11] He Q X, Huang Xiao C, Chen Z L. Influence of organic acids, complexing agents and heavy metals on thebioleaching of iron from kaolin using Fe(III)-reducing bacteria [J]. Applied Clay Science,2011,51(4):478-483.
[12] Cho Y S, Bolick J A, Butcher D J. Phytoremediation of lead with green onions (Allium fistulosum) and uptakeof arsenic compounds by moonlight ferns (Pteris cretica cv Mayii)[J], Microchemical Journal,2009,91(1):6-8.
[13]陈红琳，张世熔，李婷，等．汉源铅锌矿区植物对Pb和Zn的积累及耐性研究[J]．农业环境科学学报，2007，26（2）：107-111．
[14]赵磊．白音诺尔铅锌矿铅超富集植物筛选及其耐性研究[D]．呼和浩特：内蒙古农业大学，2009．
[15]杨远祥，邹开贵，朱雪梅，等．铅锌胁迫对铅超富集植物小鳞苔草生理代谢特性的影响[J]．陕西农业科学，2009，（6）：83-85．
[16]汤叶涛，仇荣亮，曾晓雯，等．一种新的多金属超富集植物——圆锥南芥（Arabis paniculata L.）[J]．中山大学学报（自然科学版），2005，44（4）：135-136．
[17]侯晓龙，常青山，刘国锋，等． Ｐｂ超富集植物金丝草（Pogonatherum crinitum）、柳叶箬（Lsachneglobosa）[J].环境工程学报，2012，6（3）：989-994．
[18]侯晓龙，陈加松，刘爱琴，等． Pb胁迫对金丝草和柳叶箬生长及富Pb特征的影响[J]．福建农林大学学报(自然科学版)，2012，41（3）：286-290．
[19]常青山．重金属超富集植物的筛选与螯合吸附研究[D]．福州：福建农林大学，2005．
[20] Visioli G, Marmiroli N The proteomics of heavy metal hyperaccumulation by plants [J]. Journal ofProteomics,2013,79(2）:133-145.
[21]何闪英，高永杰，申屠佳丽，等．铜和模拟酸雨复合胁迫对酸模铜富集、生长及抗氧化酶系统的影响[J]．应用生态学报，2011，22（2）：481-487．
[22] Bini C, Wahsha M, Fontana S, et al. Effects of heavy metals on morphological characteristics of Taraxacumofficinale Web growing on mine soils in NE Italy[J]. Journal of Geochemical Exploration,2012,123(12):101-108.
[23] Li T Q, Yang X E, Lu L L, et al. Effects of zinc and cadmium interactions on root morphology and metaltranslocation in a hyperaccumulating species under hydroponic conditions[J].Journal of Hazardous Materials,2009,169(1–3):734-741.
[24]马敏，龚惠红，邓泓.重金属对8种园林植物种子萌发及幼苗生长的影响[J].中国农学通报，2012，28(22):206-211.
[25]杨颍丽，王文瑞，尤佳，等.Cd2+胁迫对小麦种子萌发、幼苗生长及生理生化特性的影响[J].西北师范大学学报，2012，48（3）：88-94.
[26黄铭洪，束文圣，栾天罡，等．环境污染与生态恢复[M]．北京，科学出版社，2004，118-132．
[27]蔡佩英，刘爱琴，侯晓龙．9种水生植物对模拟污水中氮、磷的生物净化效果[J].福建农林大学学报（自然科学版），2010，39（3）：313-318．
[28] Marin A R,Masscheleyn P H, Patrick W H. Soil redox-pH stability of arsenic species and its influence onarsenic uptake by rice[J]. Plant and Soil,2004,152(2):245-253.
[29]田晓锋，魏虹，贾中民，等．重金属镉(Cd2+)对梧桐幼苗根生长及根系形态的影响[J]．西南师范大学学报(自然科学版)，2008，33（2）：93-98．
[30]贾中民，魏虹，孙晓灿，等．秋华柳和枫杨幼苗对镉的积累和耐受性[J]．生态学报，2011，31（1）：107-114．
[31]Tahar G, Issam N, Ines S, etal. Cadmium effects on growth and mineral nutrition of two ha1ophytes:SesuviumPortulacastrum and Mesembryanthemum crystallinu[J]. Journalof plant Physiology,2005,(162):133-140.
[32]刘灵，廖红，王秀荣，等．磷有效性对大豆菌根侵染的调控及其与根构型、磷效率的关系[J]．应用生态学报，2008，19（3）：564-568．
[33] Kiswara W, Behnke N, Van Avesaath P, et al. Root architecture of six tropical seagrass species, growing inthree contrasting habitats in Indonesian waters[J]. Aquatic botany,2009,90(3):235-245.
[34] Moradia A B, Conesab H M, Robinsonb B H, et al. Root responses to soil Ni heterogeneity in ahyperaccumulator and a non-accumulator species [J]. Environmental Pollution,2009,157(8):2189-2196.
[35] James J J, Mangold J M, Sheley R L, et al. Root plasticity of native and invasive Great Basin species inresponse to soil nitrogen heterogeneity[J].Plant Ecological,2009,202:211-220.
[36] Estrella G N, Mendoza C D, Moreno S R, et al. The Pb-hyperaccumulator aquatic fern Salvinia minimaBaker, responds to Pb(2+) by increasing phytochelatins via changes in SmPCS expression and inphytochelatin synthase activity [J]. Aquat Toxicol,2009,91(4):320-328.
[37]闫研，李建平，张学洪．超富集植物李氏禾对铬诱导的氧化胁迫响应[J]．生态环境，2008，17（4）：1476-1482．
[38] Hasanuzzaman M, Hossain M A, Fujiat M. Physiological and biochemical mechanisms of nitric oxideinduced abiotic stress tolerance in plants[J]. American Journal of Plant Physicology,2010,5(6):295-324.
[39] Engelen D L，Sharpe-Pedler R C，Moorhead K K. Effect of chelating agents and solubility ofcadmium complexes on uptake from soil by Brassica juncea[J].Chemosphere,2007,68：401-408.
[40] Donato R J, Roberts L A, Sanderson T, ea al. A rabidopsis Yellow Stripe-Like(YSL2): a metal regulatedgene encoding a plasma membrane transporter of nicotianamine-meal complexes[J]. Plant Journal,2004,39(3):403-414.
[41] Nehnevajova E, Lyubenova L, Herzig R, et al. Metal accumulation and response of antioxidant enzymes inseedlings and adult sunflower mutants with improved metal removal traits on a metal-contaminated soil[J].Environmental and Experimental Botany,2012,76(2):39-48.
[42] Anjum N A, Ahmad I, Mohmood I, et al. Modulation of glutathione and its related enzymes in plants’responses to toxic metals and metalloids[J]. Environmental and Experimental Botany,2012,75(1):307-324.
[43] Zhang Y, Zheng G H, Liu P, et al. Morohological and physiologicalresponses of root tip cells to Fe2+tocicityin rice[J]. ActaPhysiologiae Plantarum,2011,33(3):683-689.
[44]赵钢，邹亮，彭镰心，等.铅胁迫对苦荞生理特性的影响[J].江苏农业科学，2012,40（7）：98-100.
[45]朱启红，夏红霞.铅胁迫对蜈蚣草抗氧化酶系统和叶绿素含量的影响[J].贵州农业科学，2012,40（4）：56-58.
[46]蒋和平，郑青松，朱明，等.条浒苔和缘管浒苔对镉胁迫的生理响应比较[J].生态学报，2011,31（16）：4525-4533.
[47]高伟，魏虹，贾中民，等.香根草对镉胁迫的光合响应[J].西南师范大学学报，2012,37（10）：59-64.
[48]柴民伟，刘福春，曹迪，等. Pb对互花米草的生理特性和Pb在体内积累的影响[J].南开大学学报：自然科学版，2011，44（6）：33-40.
[49] Ingelmo F, José Molina M, Desamparados Soriano M, et al. Influence of organic matter transformations onthe bioavailability of heavy metals in a sludge based compost[J]. Journal of Environmental Management,2012,95(3):104-109.
[50] Chaumont A, Nickmilder M, Dumont X, et al. Associations between proteins and heavy metals in urine at lowenvironmental exposures: Evidence of reverse causality [J]. Toxicology Letters,2012,210(3):345-352.
[51] Rajkumar M, Sandhya S. Prasad M N V, et al. Perspectives of plant-associated microbes in heavy metalphytoremediation[J]. Biotechnology Advances,2012,30(6):1562-1574.
[52] GunNam N, Salt D E. The role of sulfur assimilation and sulfur-containing compounds in trae elementhomeostasis in plants[J]. Environmental and Experimental Botany,2011,72(1):8-25.
[53] Bennett L E，Burkhead J L，Kerry L H， et a1． Pilon-smits analysis of transgenic Indian mustard plants forphytoremediation of metal-contaminated mine tailings[J]．Journal of Environmental Quality，2003，32：432-440.
[54] Huang J W, Cunningham S D. Lead phytoextraction: species variation in lead uptake and translocation [J].New Phytologist,1996,134:75-84.
[55] Kanwar M K, Bhardwaj R, Arora P, Chowdhary S P, et al. Plant steroid hormones produced under Ni stressare involved in the regulation of metal uptake and oxidative stress in Brassica juncea L.[J]. Chemosphere,2012,86(1):41-49.
[56] Sun R L，Zhou Q X，Jin C C．Cadmium accumulation in telation to organic acids in leaves of Solanumnigrum L.as a newly found cadmium hyperaccumulator[J]．Plant and soil，2006，285(1)：125-134．
[57] Jeong S, Moon H S, Nam K, et al. Application of phosphate-solubilizing bacteria for enhancingbioavailability and phytoextraction of cadmium (Cd) from polluted soil [J]. Chemosphere,2012,88(2):204-210.
[58]李光辉，杨霞，徐加宽，等．不同湿地植物的根系酸化作用与重金属吸收[J]．生态环境学报，2009，18（1）：97-100．
[59] Nedelkoska T V, Doran P M. Hyperaccumulation of cadmium by hairy roots of Thlaspi caerulescens[J].Biotechnology and bioengineering,2000,67(5):607-615.
[60] Wojcik M, Vangronsveld J, Dhaen J, et al. Cadmiumtolerance in Thlaspi caerulescens[J]. Environmental andExperimental Botany,2005,53(2):163-171.
[61] Wang P, Zhou D M, Kinraide T B, et al. Cell menbrane surface potential plays a dominant role in thephytotoxicity of copper and arsenate[J]. Plant Physiology,2008,148,2134-2143.
[62] Li W X, Chen T B, Huang Z C, et a. Effect of arsenic on chlorop last ultrastructure and calcium distribution inarsenic hyperaccumulator Pterisvittata L[J]. Chemosphere,2006,62:803-809.
[63]包姣，韦惠琴，赵秀兰．低分子量有机酸强化烟草修复镉污染土壤的适用性研究[J]．水土保持学报，2012,26（2）：265-270．
[64]乔冬梅，樊向阳，樊涛，等．Pb2+胁迫下黑麦草对外源有机酸的响应机制[J]．水土保持学报，2012,26（2）：261-264．
[65] Magdziak Z, Kozlowska M, Kaczmarek Z, et al. Influence of Ca/Mg ratio on phytoextraction properties ofSalix viminalis. II. Secretion of low molecular weight organic acids to the rhizosphere[J]. Ecotoxicology andEnvironmental Safety,2011,74(1):33-40.
[66] Kramer U，Cotter-Howells J D，Charnock J M，et al．Free histidine as a metal chelaor in plants[J]．Nature，1996，379：635-638．
[67] Zhang Y X，Chai T Y． Research advances on the mechanisms of heavy metal tolerance in plants[J]．ActaBotanica sinca，1999，41(5)：453-457．
[68]李华，黄建国，王明霞.锰对外生菌根真菌生长、养分吸收及有机酸分泌的影响[J].背景林业大学学报，2012,34（3）：76-80.
[69]唐宇庭，黄佳玉，王维生，等.低分子有机酸对油菜吸收Cd和Zn的影响[J].广西师范大学学报：自然科学版，2012,30（2）：127-131.
[70] Bendjeffal H, Guerfi K, Bouhedja Y, et al. Immobilization of complexes of some heavy metals with a2-(4-pyridylazo)-resorcinol “PAR” on Algerian hydrothermal clay[J]. Physics Procedia,2009,2(3):889-897.
[71] Ko odyńska D. Green complexing agent—EDDS in removal of heavy metal ions on strongly basic anionexchangers[J]. Desalination,2011,280(1-3):44-57.
[72] Margoshes M, Vallee B L. Acadmium prorein from equine kidney corter[J]. Journal of the Americanchemical society,1957,79:4813-4814.
[73] Heiss S, Wachter A, Bogs J, et al. Phytochelatin synthase（PC）protein is induced in Brassica juncea leavesafter prolonged Cd exposure[J].Experimental Botany,2003,54(389):1833-1839.
[74] Janouskova M, Pavlikova D, Macek T, et al. Arbuscular mycorrhiza decreases cadmium phytoextraction bytransgenic tobacco with inserted metallothionein[J]. Plant and Soil,2005,272(1):29-40.
[75]王超，王丽娅，孙琴，等.低浓度Cd胁迫下2种水生植物体内植物络合素的响应[J].四川大学学报，2008，40（6）：87-94.
[76] Battelli R, Lombardi L, Rogers H J, et al. Changes in ultrastructure, protease and caspase-like activitiesduring flower senescence in Lilium longiflorum[J]. Plant Science,2011,180(5):716-725.
[77] Alden K P, Dhondt-Cordelier S, McDonald K L, et al. Sphingolipid long chain base phosphates can regulateapoptotic-like programmed cell death in plants[J] Biochemical and Biophysical Research Communications,2011,410(3):574-580.
[78] Vartapetian AB, Tuzhikov AI, Chichkova NV, Taliansky M, Wolpert TJ. A plant alternative to animalcaspasees: subtilisin-like proteases. Cell Death Differ,2011,18(8):1289-1297.
[79] Jiménez C, Capasso J M, Edelstein C L,et al. Different ways to die: cell death modes of the unicellularchlorophyte Dunaliella viridis exposed to various environmental stresses are mediated by the caspase-likeactivity DEVDase[J]. Journal of Experimental Botany,2009,60(3):815–828.
[80] Wangeline A L，Burkhead J L，Hale K L，et a1．Over pression of ATP sulfurylase in Indian mustard：effectson tolerance and accumulation of twelve metals[J]．Journal of Environmental Quality，2004，33(1)：54-57．
[81] Maxted A P, Black C R, West H M, et al. Phytoextraction ofcadmium and zinc from arable soils amended withsewage sludge using Thlaspi caerulescens: development of a predictive model[J]. Environmental Pollution,2007,150(3):363-372.
[82] Leitenmaier Barbara, Witt A, Witzke A, et al. Biochemical and biophysical characterisation yields insightsinto the mechanism of a Cd/Zn transporting ATPase purified from the hyperaccumulator plant Thlaspicaerulescens[J]. Biochimica et Biophysica Acta-Biomembranes,2011,1808(10):2591-2599.
[83]王爱霞，方炎明.空气重金属元素在悬铃木叶中的亚细胞分布及其区隔化效应[J].西北植物学报，2011，31（3）：479-485.
[84]王芳，丁杉，张春华，等.不同镉耐性水稻非蛋白巯基及镉的亚细胞和分子分布[J].农业环境科学学报，2010，29（4）：625-629.
[85]魏树和，杨传杰，周启星，等.三野鬼针草等7种常见菊科杂草植物对重金属的超富集特征[J].环境科学，2008，29（10）：2912-2918.
[86]张玉秀，于飞，张媛雅，等.植物对重金属镉的吸收转运和积累机制[J].中国生态农业学报，2008，16(5)：1317-1321.
[87]周守标，王春景，杨海军，等.菰和菖蒲对重金属的胁迫反应及其富集能力[J].生态学报，2007，27（1）：281-287.
[88]鲁如坤．土壤农业化学分析方法［M］．北京：中国农业科技出版社，2000．
[89]王朝文．不同温度对总状绿绒蒿种子萌发的影响［J］．种子，2009，28(2)：25-27．
[90]朱广廉,钟海文,张爱琴.植物生理实验[M].北京:北京大学出版社,1995.
[91]张志良.植物生理学实验指导[M](第二版).北京:高等教育出版社.1990:154-155.
[92]李合生.植物生理生化实验原理和技术[M].北京:高等教育出版社,2000
[93]毛达如.植物营养研究方法[M].北京:中国农业大学出版社,2005.
[94]宋金凤，崔晓阳，刘永.毛细管气相色谱法测定森林凋落物中的有机酸[J].林业科学，2004，40（4）：185-188.
[95]吴慧梅，李非里，牟华倩，等.两步连续提取法测定植物中重金属的形态[J].环境科学与技术，2012，35(7):133-137.
[96]吕静霞，张雅莉.铅胁迫对小麦种子萌发及幼苗生长的影响[J].种子，2012，31（1）：100-103.
[97] Deborah L A,Wesley M J. Proton and copper absorption to maize and soybean root cell walls[J].PlantPhysiology,1989,89:823-832.
[98] Branquinho C,Brown D H,Catarino F. The celluar location of Cu in lichens and its effects on membraneinlegrity and chlorophyII fluorescence[J]. Environmental and Experimental Botany,1997,38(2):165-179.
[99]唐为萍，陈树思，陈琳.铅处理对含羞草种子萌发及幼苗生长的影响[J].湖北农业科学，2009，48（11）：2777-2779.
[100]叶利民，樊兰紫，王爱斌.铅胁迫对不同品种小白菜种子萌发的影响[J].中国野生植物资源，2011，30（5）：51-53.
[101]康丽娜，吴福忠，何振华，等. Pb胁迫对欧美杂交杨（Populus deltoides×Populus nigra）生物量分配格局及其Pb富集特性的影响[J].农业环境科学学报，2012，31（3）：484-490.
[102] Jusselme M D, Poly F, Edouard Mi, Effect of earthworms on plant Lantana camara Pb-uptake and onbacterial communities in root-adhering soil [J]. Science of The Total Environment,2012,416(1):200-207.
[103] Chenery S R, Izquierdo M, Marzouk E, et al. Soil–plant interactions and the uptake of Pb at abandonedmining sites in the Rookhope catchment of the N. Pennines, UK—A Pb isotope study [J]. Science of TheTotal Environment,2012,433(9):547-560.
[104]林晓倩，张健，杨万勤，等.3种土壤类型下铅胁迫对巨桉幼苗的影响[J].林业科学，2013，49（1）：1-6.
[105]王宁，南忠仁，王胜利，等.Cd/Pb胁迫下油菜中重金属的分布、富集及迁移特征[J].兰州大学学报（自然科学版），2012，48（3）：18-22.
[106]胡方洁，张健，杨万勤，等.Pb胁迫对红椿（Toona ciliata Roem）生长发育及Pb富集特性的影响[J].农业环境科学学报，2013，31（2）：284-291.
[107]孟晓霞，龙巍，郑超，等.铅胁迫对西南山梗菜生长及逆境生理指标的影响[J].四川农业大学学报，2012，30（3）：336-341.
[108]陶玲，郭永春，李萍，等.铅胁迫对3种豆类作物生理特性的影响[J].中国农学通报，2012，28（33）：78-83.
[109] Gump B B, MacKenzie J A, Bendinskas K, et al. Low-level Pb and cardiovascular responses to acute stressin children: The role of cardiac autonomic regulation [J]. Neurotoxicology and Teratology,2011,33(2):212-219.
[110]夏红霞，朱启红，何超.黑麦草叶绿素荧光特性对Pb2+胁迫的响应[J].贵州农业科学，2012，40（12）：33-35.
[111]李清飞.麻疯树对铅胁迫的生理耐性研究[J].生态与农村环境学报,2012，28(1):72-76.
[112]刘慧芹，韩巨才，刘慧平，等.铅梯度胁迫对多年生黑麦草幼苗生理生化特性影响[J].草业学报.2012,21(6):57-63.
[113] Basic N, Salamin N, Keller C,et al. Cadmium hyperaccumulation and genetic differentiation of Thlaspicaerulescens populations[J].Biochemical Systematics and Ecology,2006,34(9):667-677.
[114] Maestri E, Marmiroli M, Visioli G, et al. Metal tolerance and hyperaccumulation: Costs and trade-offsbetween traits and environment[J].Environmental and Experimental Botany,2010,68(1):1-13.
[115]赵红芳，黄宝康.重金属胁迫下药用植物耐受及超富集的机制[J].药学实践杂志，2010,28（6）：406-467.
[116]麦维军，王颖，梁承邺，等.谷胱甘肽在植物抗逆中的作用[J].广西植物，2005,25（6）：570.
[117] Jose J, Giridhar R, Anas A,et al. Heavy metal pollution exerts reduction/adaptation in the diversity andenzyme expression profile of heterotrophic bacteria in Cochin estuary, India [J].Environmental Pollution,2011,159(10):2775-2780.
[118]李文学，陈同斌.超富集植物吸收富集重金属的生理和分子生物学机制[J].应用生态学报，2003,14（4）：627.
[119] Vollenweider P, Bernasconi P, Gautschi H, et al. Compartmentation of metals in foliage of Populus tremulagrown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles[J].EnvironmentalPollution,2011,159(1):337-347.
[120] Cang L, Zhou D M, Wang Q Y, et al. Impact of electrokinetic-assisted phytoremediation of heavy metalcontaminated soil on its physicochemical properties, enzymatic and microbial activities [J].ElectrochimicaActa,2012,86(30):41-48.
[121] Maestri E, Marmiroli M, Visioli G, et al. Metal tolerance and hyperaccumulation: Costs and trade-offsbetween traits and environment[J]. Environmental and Experimental Botany,2010,68(1):1-13.
[122] Kim S, Lim H, Lee I. Enhanced heavy metal phytoextraction by Echinochloa crus-galli using rootexudates[J]. Journal of Bioscience and Bioengineering,2010,109(1):47-50.
[123] Manzoor Q, Nadeem R, Iqbal M, et al. Organic acids pretreatment effect on Rosa bourbonia phyto-biomassfor removal of Pb(II) and Cu(II) from aqueous media[J]. Bioresource Technology,2013,132,446-452.
[124] He Q X, Huang X C, Chen Z L. Influence of organic acids, complexing agents and heavy metals on thebioleaching of iron from kaolin using Fe(III)-reducing bacteria[J]. Applied Clay Science,2011,51(4):478-483.
[125]吴双桃，吴晓芙，胡曰利，等.铅锌冶炼厂土壤污染及重金属富集植物研究[J].生态环境，2004,13（2）：156.
[126]王飞，胥焘，张晟，等. Pb、Cd单一及复合胁迫对桂花幼苗生理生化特性的影响[J].三峡环境与生态，2013,35（1）：3-7.
[127]王启明．铅、镉单一及复合胁迫对玉米幼苗生理生化特性的影响[Ｊ]．安徽农业科学，2006，34（10）：2036-2037．
[128]徐学华，黄大庄，王连芳，等．土壤铅、镉胁迫对红瑞木生长及生理生化特性的影响[J].水土保持学报，2009，23(1)：213-216．
[129] Phillips C J C, Mohamed M O, Chiy P C. Effects of duration of exposure to dietary lead on rumenmetabolism and the accumulation of heavy metals in sheep [J]. Small Ruminant Research,2011,100(2-3):113-121.
[130] Kerr J FR, Wyllie AH,Currie A R.Apoptosis:a basic biological phenomenon with wideranging implicationsin tissue kinetics. British Journal of Cancer,1972,26:239-257.
[131] Wouter G. van Doorn.Classes of programmed cell death in plants, compared to those in animals[J]. Journal ofExperimental botany,2011,62(14):4749-4761.
[132] Manzoor H, Chiltz A, Madani S, et al. Calcium signatures and signaling in cytosol and organelles of tobaccocells induced by plant defense elicitors[J]. CellCalcium,2012,51(6):434-444.
[133] Petrov V, Vermeirssen V, Clercq I D, et al. Identification of cis-regulatory elements specific for differenttypes of reactive oxygen species in Arabidopsis thaliana[J]. Gene,2012,499(1):52-60.
[134] Sergey Shabala.Commentary: Salinity and programmed cell death: unravelling mechanisms for ion specificsignalling, Journal of Experimental botany,2009,60(3):709-712.
[135] Reape T J, Molony E M. Programmed cell death in plants: distinguishing between different modes[J].Journal of Experimental botany,2008,59(3):435-444.
[136] Sobkowiak R, Gzyl J, Pawlak-Sprada S, et al. Nitric oxide implication in cadmium-induced programmed celldeath in roots and signaling response of yellow lupine plants[J]. Plant Physiology and Biochemistry,2012,58(9):124-134.
[137] Arasimowicz-Jelonek M, Floryszak-Wieczorek J, Deckert J, et al. Nitric oxide implication incadmium-induced programmed cell death in roots and signaling response of yellow lupine plants[J]. PlantPhysiology and Biochemistry,2012,58(9):124-134.
[138] Panda K K, Achary V M, Krishnaveni R. In vitro biosynthesis and genotoxicity bioassay of silvernanoparticles using plants[J]. Toxicology in Vitro,2011,25（5）：1097-1105.