摘要
为了系统了解根系与水分的相互作用机制,科学地指导黄土高原地区造林树种选择和造林实践,本文以油松(Pinus tabulaeformis)、刺槐(Robinia pseudoacacia)、侧柏(Platycladus orientalis)、沙棘(Hippophae rhamnoides)等4个黄土高原主要造林树种2年生苗木为材料,通过人为控制土壤水分(按土壤田间持水量的70%、50%、35%设干旱处理水平,各水平持续处理时间均设7 d、14 d和21 d),研究了苗木根系生物量、细根(Φ<2 mm)形态特征(表面积、根长、根尖数)对不同程度、不同持续时间的干旱的反应,并分析了各部分物质分配格局的变化;同时分析了干旱条件下4个树种根尖可溶性蛋白含量以及各组分含量的变化。研究结果表明:
(1)随着胁迫程度和处理时间的增加,油松根生物量和细根指标显著增加;刺槐根生物量总体上有增加,细根指标保持稳定;侧柏根生物量在中度干旱增加,重度干旱减少,两水平处理随着处理时间的延长均有减少的趋势,细根指标仅在重度干旱(21 d)明显减少;沙棘根生物量、细根指标在中度干旱条件下明显增加,但随着处理时间的延长,增加量逐渐减少,重度干旱条件不能存活。
(2)干旱条件下,根、茎、叶的物质分配格局除油松外,均发生了变化,树种之间差异很大。随着干旱程度和处理的增加,油松各部分生物量按照稳定的比例增加;刺槐在中度干旱21 d和重度干旱条件下,有机合成呈负增长,物质由叶向根和茎集中;侧柏在重度干旱条件下,有机物质合成受阻,并由根向茎集中;沙棘中度干旱条件光合产物主要向叶分配。
(3)刺槐根尖可溶性蛋白含量在中度干旱7d减少,较长期(14d、21d)中度干旱和较短期(7d)重度干旱下增加,较长期(21d)重度干旱下减少;侧柏在较短期(7d)中度干旱和重度干旱下增加,较长期中度干旱(21d)和重度干旱(14d、21d)下减少;随着胁迫程度和处理时间的增加,油松总体增加,沙棘则减少。可溶性蛋白组分无变化,大多数蛋白含量变化与总蛋白含量变化趋于一致。苗木根尖的可溶性蛋白含量的变化在不同程度和时间的干旱以及树种之间差异较大,其对干旱的响应是通过大部分蛋白组分较一致地变化而实现的。
(4)在利用常规SDS-PAGE方法分离刺槐根系可溶性蛋白的过程中,发现其分离效果不好。将样品处理液中SDS、β-巯基乙醇、丙三醇的含量均增加了50%。改进后的方法得到了分离效果明显较常规方法好的电泳图谱。经分析得出:常规SDS-PAGE方法中样品处理液的SDS和β-巯基乙醇浓度不足以充分溶解刺槐根系中的可溶性蛋白,丙三醇的浓度也不足以将样品很好地沉聚于点样槽底部。试验为植物组织可溶性蛋白的SDS-PAGE分离提供了一套效果较好的参考方法。
For systemic researching the interreaction mechanism between root and water,guiding the choosing of sivilculture species and sivilculture practice scientifically,the study choosed 2 year-old seedlings of Pinus tabulaeformis,Robinia pseudoacacia,Platycladus orientalis and Hippophae rhamnoides which are the main tree species on Loess Plateau as material. An artificial controlling soilmoisture(70%, 50% and 35%WHC three levels, time of each treatment level is 7 d, 14 d and 21 d)test was made to observe responses of root biomass, aboveground biomass,fine roo(tΦ<2 mm)indexes(surface area,length and tips quantity),and the mass allocation pattern of each part to varying stress degree and dealing time of drought condition;Besides,a analysis was made to study the changes of contents and components for soluble protein in their roots tips. The result showed that:
(1)With the increasing stress degree and dealing time,the root biomass and fine root indexes of Pinus tabulaeformis augment markedly;The root biomass of Robinia pseudocacia increases totally,but fine root indexes maintain stable;The root biomass of Platycladus orientalis increases on moderate drought but decreases on severe drought,and the two levels have the decreasing trend with the increasing dealing time,and fine root indexes reduce significantly only on severe drought(21 d);The root biomass and fine root indexes of Hippophae rhamnoides increase obviously on moderate drought condition but the increasing amount decreases for longer dealing time,and it can not survive on severe drought condition.
(2)The mass allocation pattern of root,stem and leaf changes on drought,and there are significant difference among tree species. With the increasing stress degree and dealing time,every part biomass of Pinus tabulaeformis increases by a stable proportion;Robinia pseudocacia’s organic synthesis presents negative growth on moderate(21 d)and severe drought,and material centralizes to root and stem from leaf;Platycladus orientalis’organic synthesis is blocked on severe drought,and material centralizes to stem from root;Hippophae rhamnoides’photosynthetic product is mainly distributed to leaf.
(3)Content of soluble protein in root tips of Robinia pseudoacacia decreases on moderate drought for 7d,and increases in longer time (14d,21d) moderate drought and shorter time(7d)severe drought,and decreases on longer(21d)severe drought;Platycladus orientalis increased in shorter time(7d)moderate and severe drought,and decreases on longer time moderat(e21d)and sever(e14d,21d)drought;With the increasing of stress degree and treatment time,the content of soluble protein in Pinus tabulaeformis generally increased while Hippophae rhamnoides decreases.The soluble protein components in root tips of four trees do not change on drought,and the variation of content in most kinds of protein have the similar trends to the total.The soluble protein content in seedings root tips changing are big difference among degrees,treatment time of drought and tree species,and its responses to drought are realized by coincident change of the most of proteins components.
(4)In the course of using the regular SDS-PAGE method to separate the soluble protein of Robinia Pseudoacacia root tips,the result was found not very good. The experiment increased the content of SDS,β-mercaptoethanol and glycerine in treating solution for sample by 50% and the separating effect in improved method is much better. After analysis,in treating solution for sample,the deficiency of SDS andβ-mercaptoethanol content which resulted in the insufficient dissolution of soluble protein of Robinia Pseudoacacia root and the deficiency of glycerine content which resulted in inferior sinking and congregating when supplied samples are the reasons of bad separating effect. The experiment supplys a better reference method of SDS-PAGE for separating soluble protein of plant tissue.
引文
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