短期夜间增温对亚高山针叶林云杉幼苗根系分泌物速率和化学成分的影响
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摘要
以连续7a红外辐射增温处理下的云杉幼苗为对象,定量分析了增温对植物根系碳(C)、氮(N)分泌速率以及主要挥发性化学成分的影响。结果表明:(1)增温显著增加了云杉幼苗根系C分泌速率,而对N分泌速率无显著影响,并伴随着根系分泌物C∶N化学计量比显著增加;(2)不同化学组分输入含量变化对增温的响应具有明显差异,其响应幅度和方向与化学组分种类有关。其中糖类、氨基酸和酚类化合物的含量在增温处理下均显著增加,而酯类、醚类相对含量显著降低;(3)进一步分析表明,同组分中不同化合物成分含量对增温的响应也有所差异。例如,增温仅导致酚类化合物中2,6-二叔丁基-4-甲基苯酚和4-叔丁基杯[4]芳烃含量显著增加(分别比对照增加了88.9%和375.7%),而对其余酚类化合物成分含量无显著影响。结果表明增温可导致植物根系分泌物各组分相对含量发生深刻地变化,这对于进一步认识不同环境变化下根系分泌物输入及其所诱导的特异性土壤微生物养分过程具有重要的理论意义。
While it is well recognized that root exudates play a crucial role in driving belowground biogeochemical processes,few studies have attempted to examine the effects of elevated temperature on the rates and chemical components of root exudation in forests. In this study,we conducted a night-time warming experiment by using an infrared heating device to explore the ecological consequences of warming on the rates and chemical components of root exudation by Picea asperataseedlings. Root exudates were collected from intact fine roots of plants growing in the warmed plots and the control plots using a modified culture-based cuvette system,developed especially for collecting field-based exudates. The concentrations of total organic carbon( TOC) and total nitrogen( TN) in the root exudates were quantitatively investigated,and expressed as the C and N exudation rates for P. asperata seedlings. Furthermore,the main chemical components of root exudates were quantified using the gas chromatography and mass spectrometry( GC-MS) method. The results showed the following:( 1) Experimental warming considerably increased the root C exudation rates( μg C g-1 root biomass h-1). In contrast,no significant effects were observed on the root N exudation rates( μg N g-1 root biomass h-1),which led to a significant increase in the C ∶ N ratio of the root exudates.( 2) Experimental warming had significant effects on the relative contents of chemical compounds,and the response magnitude and direction to experimental warming were closely related to the components of the chemical compounds. Specifically,the relative contents of sugars,amino acids,and phenolics were significantly increased by warming,while the relative contents of esters and ethers markedly decreased.( 3) Experimental warming had significant effects on the contents of different chemical components in root exudates. For example,the relative contents of two phenolics,2,6-Di-tert-butyl-4-methylphenol and 4-Tert-butylcalix [4] arene,increased by 88. 9% and 375.7%,respectively,compared to the control plots,but no significant differences were observed for the other components.Collectively,our results suggested that experimental warming can lead to profound influences on the exudation rates and the relative contents of the specific exudate components,which provides a theoretical foundation that can improve understanding of the soil C-nutrient cycling process mediated by root exudation inputs in subalpine coniferous forests when P. asperata is subjected to environmental changes.
While it is well recognized that root exudates play a crucial role in driving belowground biogeochemical processes,few studies have attempted to examine the effects of elevated temperature on the rates and chemical components of root exudation in forests. In this study,we conducted a night-time warming experiment by using an infrared heating device to explore the ecological consequences of warming on the rates and chemical components of root exudation by Picea asperataseedlings. Root exudates were collected from intact fine roots of plants growing in the warmed plots and the control plots using a modified culture-based cuvette system,developed especially for collecting field-based exudates. The concentrations of total organic carbon( TOC) and total nitrogen( TN) in the root exudates were quantitatively investigated,and expressed as the C and N exudation rates for P. asperata seedlings. Furthermore,the main chemical components of root exudates were quantified using the gas chromatography and mass spectrometry( GC-MS) method. The results showed the following:( 1) Experimental warming considerably increased the root C exudation rates( μg C g-1 root biomass h-1). In contrast,no significant effects were observed on the root N exudation rates( μg N g-1 root biomass h-1),which led to a significant increase in the C ∶ N ratio of the root exudates.( 2) Experimental warming had significant effects on the relative contents of chemical compounds,and the response magnitude and direction to experimental warming were closely related to the components of the chemical compounds. Specifically,the relative contents of sugars,amino acids,and phenolics were significantly increased by warming,while the relative contents of esters and ethers markedly decreased.( 3) Experimental warming had significant effects on the contents of different chemical components in root exudates. For example,the relative contents of two phenolics,2,6-Di-tert-butyl-4-methylphenol and 4-Tert-butylcalix [4] arene,increased by 88. 9% and 375.7%,respectively,compared to the control plots,but no significant differences were observed for the other components.Collectively,our results suggested that experimental warming can lead to profound influences on the exudation rates and the relative contents of the specific exudate components,which provides a theoretical foundation that can improve understanding of the soil C-nutrient cycling process mediated by root exudation inputs in subalpine coniferous forests when P. asperata is subjected to environmental changes.
引文
[1]Bj9rk R G,Majdi H,Klemedtsson L,Lewis-Jonsson L,Molau U.Long-term warming effects on root morphology,root mass distribution,and microbial activity in two dry tundra plant communities in northern Sweden.New Phytologist,2007,176(4):862-873.
[2]Volder A,Gifford R M,Evans J R.Effects of elevated atmospheric CO2,cutting frequency,and differential day/night atmospheric warming on root growth and turnover of Phalaris swards.Global Change Biology,2007,13(5):1040-1052.
[3]涂书新,吴佳.植物根系分泌物研究方法评述.生态环境学报,2010,19(10):2493-2500.
[4]Dijkstra F A,Cheng W X.Interactions between soil and tree roots accelerate long-term soil carbon decomposition.Ecology Letters,2007,10(11):1046-1053.
[5]吴林坤,林向民,林文雄.根系分泌物介导下植物-土壤-微生物互作关系研究进展与展望.植物生态学报,2014,38(3):298-310.
[6]Phillips R P,Finzi A C,Bernhardt E S.Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2fumigation.Ecology Letters,2011,14(2):187-194.
[7]Finzi A C,Abramoff R Z,Spiller K S,Brzostek E R,Darby B A,Kramer M A,Phillips R P.Rhizosphere processes are quantitatively important components of terrestrial carbon and nutrient cycles.Global Change Biology,2015,21(5):2082-2094.
[8]Keiluweit M,Bougoure J J,Nico P S,Pett-Ridge J,Weber P K,Kleber M.Mineral protection of soil carbon counteracted by root exudates.Nature Climate Change,2015,5(6):588-595.
[9]Drake J E,Gallet-Budynek A,Hofmockel K S,Bernhardt E S,Billings S A,Jackson R B,Johnsen K S,Lichter J,Mc Carthy H R,Mc Cormack M L,Moore D J P,Oren R,Palmroth S,Phillips R P,Pippen J S,Pritchard S G,Treseder K K,Schlesinger W H,Delucia E H,Finzi A C.Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2.Ecology Letters,2011,14(4):349-357.
[10]Cheng W X,Parton W J,Gonzalez-Meler M A,Phillips R,Asao S,Mc Nickle G G,Brzostek E,Jastrow J D.Synthesis and modeling perspectives of rhizosphere priming.New Phytologist,2014,201(1):31-44.
[11]IPCC.Climate Change 2014:Synthesis Report.Contribution of Working Groups I,II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.Geneva,Switzerland:IPCC,2014.
[12]Pe1uelas J,Sardans J,Estiarte M,Ogaya R,Carnicer J,Coll M,Barbeta A,Rivas-Ubach A,LlusiàJ,Garbulsky M,Filella I,Jump S A.Evidence of current impact of climate change on life:a walk from genes to the biosphere.Global Change Biology,2013,19(8):2303-2338.
[13]Xu M H,Peng F,You Q G,Guo J,Tian X F,Xue X,Liu M.Year-round warming and autumnal clipping lead to downward transport of root biomass,carbon and total nitrogen in soil of an alpine meadow.Environmental and Experimental Botany,2015,109:54-62.
[14]Wu Y B,Zhang J,Deng Y C,Wu J,Wang S P,Tang Y H,Cui X Y.Effects of warming on root diameter,distribution,and longevity in an alpine meadow.Plant Ecology,2014,215(9):1057-1066.
[15]Yin H J,Li Y F,Xiao J,Xu Z F,Cheng X Y,Liu Q.Enhanced root exudation stimulates soil nitrogen transformations in a subalpine coniferous forest under experimental warming.Global Change Biology,2013,19(7):2158-2167.
[16]Brzostek E R,Greco A,Drake J E,Finzi A C.Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils.Biogeochemistry,2013,115(1/3):65-76.
[17]Zhang Z L,Qiao M F,Li D D,Zhao C Z,Li Y J,Yin H J,Liu Q.Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass.Chemistry and Ecology,2015,31(7):636-649.
[18]尹华军,赖挺,程新颖,蒋先敏,刘庆.增温对川西亚高山针叶林内不同光环境下红桦和岷江冷杉幼苗生长和生理的影响.植物生态学报,2008,32(5):1072-1083.
[19]李月蛟,朱利英,尹华军,刘庆,蒋先敏,赵春章.连续三年夜间增温和施氮对云杉外生菌根及菌根真菌多样性的影响.生态学报,2015,35(9):2967-2977.
[20]陈智,尹华军,卫云燕,刘庆.夜间增温和施氮对川西亚高山针叶林土壤有效氮和微生物特性的短期影响.植物生态学报,2010,34(11):1254-1264.
[21]卫云燕,尹华军,刘庆,黎云祥.夜间增温和施肥对川西亚高山针叶林两种树苗根际效应的影响.生态学报,2011,31(3):698-708.
[22]汤灿辉,彭新君,文礼章,江星明.蒽酮-硫酸比色法测定三叶虫茶中总糖的含量.湖南中医药大学学报,2008,28(5):38-40.
[23]Jones D L,Owen A G,Farrar J F.Simple method to enable the high resolution determination of total free amino acids in soil solutions and soil extracts.Soil Biology and Biochemistry,2002,34(12):1893-1902.
[24]石鑫,魏天兴,陈珏,解建强,周毅.低效刺槐林根系分泌物的GC-MS分析.湖南农业科学,2011,(15):135-137,142-142.
[25]Phillips R P,Meier I C,Bernhardt E S,Grandy A S,Wickings K,Finzi A C.Roots and fungi accelerate carbon and nitrogen cycling in forests exposed to elevated CO2.Ecology Letters,2012,15(9):1042-1049.
[26]Uselman S M,Qualls R G,Thomas R B.Effects of increased atmospheric CO2,temperature,and soil N availability on root exudation of dissolved organic carbon by a N-fixing tree(Robinia pseudoacacia L.).Plant and Soil,2000,222(1/2):191-202.
[27]Yin H J,Xiao J,Li Y F,Chen Z,Cheng X Y,Zhao C Z,Liu Q.Warming effects on root morphological and physiological traits:the potential consequences on soil C dynamics as altered root exudation.Agricultural and Forest Meteorology,2013,180:287-296.
[28]Treseder K K,Holden S R.Fungal carbon sequestration.Science,2013,339(6127):1528-1529.
[29]Qiao M F,Zhang Z L,Li Y J,Xiao J,Yin H J,Yue B S,Liu Q.Experimental warming effects on root nitrogen absorption and mycorrhizal infection in a subalpine coniferous forest.Scandinavian Journal of Forest Research,2016,31(4):347-354.
[30]梁儒彪,梁进,乔明锋,徐振锋,刘庆,尹华军.模拟根系分泌物C∶N化学计量特征对川西亚高山森林土壤碳动态和微生物群落结构的影响.植物生态学报,2015,39(5):466-476.
[31]刘军,温学森,郎爱东.植物根系分泌物成分及其作用的研究进展.食品与药品,2007,9(03A):63-65.
[32]Haase S,Neumann G,Kania A,Kuzyakov Y,R9mheld V,Kandeler E.Elevation of atmospheric CO2and N-nutritional status modify nodulation,nodule-carbon supply,and root exudation of Phaseolus vulgaris L.Soil Biology and Biochemistry,2007,39(9):2208-2221.
[33]Yin H J,Xu Z F,Chen Z,Wei Y Y,Liu Q.Nitrogen transformation in the rhizospheres of two subalpine coniferous species under experimental warming.Applied Soil Ecology,2012,59:60-67.
[34]Kuzyakov Y,Cheng W.Photosynthesis controls of rhizosphere respiration and organic matter decomposition.Soil Biology and Biochemistry,2001,33(14):1915-1925.
[35]贺永华,沈东升,朱荫湄.根系分泌物及其根际效应.科技通报,2006,22(6):761-766.
[36]Aroca R,Ruiz-Lozano J M.Induction of plant tolerance to semi-arid environments by beneficial soil microorganisms——a review//Lichtfouse E,ed.Climate Change,Intercropping,Pest Control and Beneficial Microorganisms.Netherlands:Springer,2009:121-135.
[37]Graham R D.Genotypic differences in tolerance to manganese deficiency//Graham R D,Hannam R J,Uren N C,eds.Manganese in Soils and Plants.Dordrecht:Springer,1988:261-276.
[38]Steinkellner S,Lendzemo V,Langer I,Schweiger P,Khaosaad T,Toussaint J P,Vierheilig H.Flavonoids and strigolactones in root exudates as signals in symbiotic and pathogenic plant-fungus interactions.Molecules,2007,12(7):1290-1306.
[39]Lattanzio V,Lattanzio V M T,Cardinali A.Role of phenolics in the resistance mechanisms of plants against fungal pathogens and insects//Imperato F,ed.Phytochemistry:Advances in Research.Trivandrum:Research Signpost,2006:23-67.
[40]Li Z H,Wang Q,Ruan X,Pan C D,Jiang D A.Phenolics and plant allelopathy.Molecules,2010,15(12):8933-8952.
[41]申建波,张福锁.根分泌物的生态效应.中国农业科技导报,1999,1(4):21-27.
[42]谢星光,陈晏,卜元卿,戴传超.酚酸类物质的化感作用研究进展.生态学报,2014,34(22):6417-6428.
[43]Paterson E,Gebbing T,Abel C,Sim A,Telfer G.Rhizodeposition shapes rhizosphere microbial community structure in organic soil.New Phytologist,2007,173(3):600-610.
[2]Volder A,Gifford R M,Evans J R.Effects of elevated atmospheric CO2,cutting frequency,and differential day/night atmospheric warming on root growth and turnover of Phalaris swards.Global Change Biology,2007,13(5):1040-1052.
[3]涂书新,吴佳.植物根系分泌物研究方法评述.生态环境学报,2010,19(10):2493-2500.
[4]Dijkstra F A,Cheng W X.Interactions between soil and tree roots accelerate long-term soil carbon decomposition.Ecology Letters,2007,10(11):1046-1053.
[5]吴林坤,林向民,林文雄.根系分泌物介导下植物-土壤-微生物互作关系研究进展与展望.植物生态学报,2014,38(3):298-310.
[6]Phillips R P,Finzi A C,Bernhardt E S.Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2fumigation.Ecology Letters,2011,14(2):187-194.
[7]Finzi A C,Abramoff R Z,Spiller K S,Brzostek E R,Darby B A,Kramer M A,Phillips R P.Rhizosphere processes are quantitatively important components of terrestrial carbon and nutrient cycles.Global Change Biology,2015,21(5):2082-2094.
[8]Keiluweit M,Bougoure J J,Nico P S,Pett-Ridge J,Weber P K,Kleber M.Mineral protection of soil carbon counteracted by root exudates.Nature Climate Change,2015,5(6):588-595.
[9]Drake J E,Gallet-Budynek A,Hofmockel K S,Bernhardt E S,Billings S A,Jackson R B,Johnsen K S,Lichter J,Mc Carthy H R,Mc Cormack M L,Moore D J P,Oren R,Palmroth S,Phillips R P,Pippen J S,Pritchard S G,Treseder K K,Schlesinger W H,Delucia E H,Finzi A C.Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2.Ecology Letters,2011,14(4):349-357.
[10]Cheng W X,Parton W J,Gonzalez-Meler M A,Phillips R,Asao S,Mc Nickle G G,Brzostek E,Jastrow J D.Synthesis and modeling perspectives of rhizosphere priming.New Phytologist,2014,201(1):31-44.
[11]IPCC.Climate Change 2014:Synthesis Report.Contribution of Working Groups I,II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.Geneva,Switzerland:IPCC,2014.
[12]Pe1uelas J,Sardans J,Estiarte M,Ogaya R,Carnicer J,Coll M,Barbeta A,Rivas-Ubach A,LlusiàJ,Garbulsky M,Filella I,Jump S A.Evidence of current impact of climate change on life:a walk from genes to the biosphere.Global Change Biology,2013,19(8):2303-2338.
[13]Xu M H,Peng F,You Q G,Guo J,Tian X F,Xue X,Liu M.Year-round warming and autumnal clipping lead to downward transport of root biomass,carbon and total nitrogen in soil of an alpine meadow.Environmental and Experimental Botany,2015,109:54-62.
[14]Wu Y B,Zhang J,Deng Y C,Wu J,Wang S P,Tang Y H,Cui X Y.Effects of warming on root diameter,distribution,and longevity in an alpine meadow.Plant Ecology,2014,215(9):1057-1066.
[15]Yin H J,Li Y F,Xiao J,Xu Z F,Cheng X Y,Liu Q.Enhanced root exudation stimulates soil nitrogen transformations in a subalpine coniferous forest under experimental warming.Global Change Biology,2013,19(7):2158-2167.
[16]Brzostek E R,Greco A,Drake J E,Finzi A C.Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils.Biogeochemistry,2013,115(1/3):65-76.
[17]Zhang Z L,Qiao M F,Li D D,Zhao C Z,Li Y J,Yin H J,Liu Q.Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass.Chemistry and Ecology,2015,31(7):636-649.
[18]尹华军,赖挺,程新颖,蒋先敏,刘庆.增温对川西亚高山针叶林内不同光环境下红桦和岷江冷杉幼苗生长和生理的影响.植物生态学报,2008,32(5):1072-1083.
[19]李月蛟,朱利英,尹华军,刘庆,蒋先敏,赵春章.连续三年夜间增温和施氮对云杉外生菌根及菌根真菌多样性的影响.生态学报,2015,35(9):2967-2977.
[20]陈智,尹华军,卫云燕,刘庆.夜间增温和施氮对川西亚高山针叶林土壤有效氮和微生物特性的短期影响.植物生态学报,2010,34(11):1254-1264.
[21]卫云燕,尹华军,刘庆,黎云祥.夜间增温和施肥对川西亚高山针叶林两种树苗根际效应的影响.生态学报,2011,31(3):698-708.
[22]汤灿辉,彭新君,文礼章,江星明.蒽酮-硫酸比色法测定三叶虫茶中总糖的含量.湖南中医药大学学报,2008,28(5):38-40.
[23]Jones D L,Owen A G,Farrar J F.Simple method to enable the high resolution determination of total free amino acids in soil solutions and soil extracts.Soil Biology and Biochemistry,2002,34(12):1893-1902.
[24]石鑫,魏天兴,陈珏,解建强,周毅.低效刺槐林根系分泌物的GC-MS分析.湖南农业科学,2011,(15):135-137,142-142.
[25]Phillips R P,Meier I C,Bernhardt E S,Grandy A S,Wickings K,Finzi A C.Roots and fungi accelerate carbon and nitrogen cycling in forests exposed to elevated CO2.Ecology Letters,2012,15(9):1042-1049.
[26]Uselman S M,Qualls R G,Thomas R B.Effects of increased atmospheric CO2,temperature,and soil N availability on root exudation of dissolved organic carbon by a N-fixing tree(Robinia pseudoacacia L.).Plant and Soil,2000,222(1/2):191-202.
[27]Yin H J,Xiao J,Li Y F,Chen Z,Cheng X Y,Zhao C Z,Liu Q.Warming effects on root morphological and physiological traits:the potential consequences on soil C dynamics as altered root exudation.Agricultural and Forest Meteorology,2013,180:287-296.
[28]Treseder K K,Holden S R.Fungal carbon sequestration.Science,2013,339(6127):1528-1529.
[29]Qiao M F,Zhang Z L,Li Y J,Xiao J,Yin H J,Yue B S,Liu Q.Experimental warming effects on root nitrogen absorption and mycorrhizal infection in a subalpine coniferous forest.Scandinavian Journal of Forest Research,2016,31(4):347-354.
[30]梁儒彪,梁进,乔明锋,徐振锋,刘庆,尹华军.模拟根系分泌物C∶N化学计量特征对川西亚高山森林土壤碳动态和微生物群落结构的影响.植物生态学报,2015,39(5):466-476.
[31]刘军,温学森,郎爱东.植物根系分泌物成分及其作用的研究进展.食品与药品,2007,9(03A):63-65.
[32]Haase S,Neumann G,Kania A,Kuzyakov Y,R9mheld V,Kandeler E.Elevation of atmospheric CO2and N-nutritional status modify nodulation,nodule-carbon supply,and root exudation of Phaseolus vulgaris L.Soil Biology and Biochemistry,2007,39(9):2208-2221.
[33]Yin H J,Xu Z F,Chen Z,Wei Y Y,Liu Q.Nitrogen transformation in the rhizospheres of two subalpine coniferous species under experimental warming.Applied Soil Ecology,2012,59:60-67.
[34]Kuzyakov Y,Cheng W.Photosynthesis controls of rhizosphere respiration and organic matter decomposition.Soil Biology and Biochemistry,2001,33(14):1915-1925.
[35]贺永华,沈东升,朱荫湄.根系分泌物及其根际效应.科技通报,2006,22(6):761-766.
[36]Aroca R,Ruiz-Lozano J M.Induction of plant tolerance to semi-arid environments by beneficial soil microorganisms——a review//Lichtfouse E,ed.Climate Change,Intercropping,Pest Control and Beneficial Microorganisms.Netherlands:Springer,2009:121-135.
[37]Graham R D.Genotypic differences in tolerance to manganese deficiency//Graham R D,Hannam R J,Uren N C,eds.Manganese in Soils and Plants.Dordrecht:Springer,1988:261-276.
[38]Steinkellner S,Lendzemo V,Langer I,Schweiger P,Khaosaad T,Toussaint J P,Vierheilig H.Flavonoids and strigolactones in root exudates as signals in symbiotic and pathogenic plant-fungus interactions.Molecules,2007,12(7):1290-1306.
[39]Lattanzio V,Lattanzio V M T,Cardinali A.Role of phenolics in the resistance mechanisms of plants against fungal pathogens and insects//Imperato F,ed.Phytochemistry:Advances in Research.Trivandrum:Research Signpost,2006:23-67.
[40]Li Z H,Wang Q,Ruan X,Pan C D,Jiang D A.Phenolics and plant allelopathy.Molecules,2010,15(12):8933-8952.
[41]申建波,张福锁.根分泌物的生态效应.中国农业科技导报,1999,1(4):21-27.
[42]谢星光,陈晏,卜元卿,戴传超.酚酸类物质的化感作用研究进展.生态学报,2014,34(22):6417-6428.
[43]Paterson E,Gebbing T,Abel C,Sim A,Telfer G.Rhizodeposition shapes rhizosphere microbial community structure in organic soil.New Phytologist,2007,173(3):600-610.