硅对金丝小枣盐胁迫的缓解效应及其机理

【作者】 刘永霞；

【导师】 徐锡增；

【作者基本信息】 南京林业大学 ， 森林培育， 2007， 博士

【摘要】 盐碱是枣树生长、枣果产量提高的重要逆境。国内外对枣树耐盐生理与调控技术的研究甚少。硅是土壤中仅次于氧的第二个最富集的元素，但土壤中的有效硅含量普遍很低，硅的作用及抗性机理正受到关注和重视。本文以1年生金丝小枣嫁接苗为试材，采用大棚盆栽试验方法，通过电子显微分析技术、能谱分析技术、高效液相色谱法等从细胞超微结构、离子微域分布、多胺形态及含量、矿质元素的吸收和分配、酶活性及其它一些生理指标研究了硅与金丝小枣耐盐性的关系，以期阐明硅对缓解盐胁迫的效应和作用机理。主要结论如下：第一，随着NaCl浓度的提高，金丝小枣苗木高生长量、地径增长量、生物量增量总体均呈下降趋势，在盐分浓度≤0.3％时，加硅后，苗木高生长量、地径增长量、生物量增量均随施硅浓度的提高而增加，在盐分浓度为0.4％时，加硅后，苗木高生长量、地径增长量、生物量增量均有不同程度的增加，其中以施硅量0.5‰的处理增加幅度较大。第二，在盐浓度为0.2％时，金丝小枣细胞没有发生质壁分离现象，在土壤含盐量为0.3％和0.4％浓度的盐胁迫下金丝小枣叶片超微结构发生了显著的变化，叶绿体双层膜脱落，基质片层结构破坏，淀粉粒减少，加硅则减轻了盐胁迫对金丝小枣细胞超微结构的伤害，维持了叶绿体片层结构完整，膜系统破损大办减小，叶绿体衰老与解体得以延缓，表明盐胁迫下加硅可以保护光合系统的功能免受伤害，增强了渗透调节能力。第三，随着NaCl浓度的提高，金丝小枣根、茎、叶中Na~+和Cl~-的含量及Na~+／K~+比值均大幅升高，K~+含量则降低，加硅后，金丝小枣根和叶中Na~+和Cl~-的含量及Na~+／K~+比值显著下降，K~+含量增加，表明硅维持了盐胁迫下枣树体内的离子平衡和离子稳态。第四，盐胁迫下加硅处理后，金丝小枣根中离子的微域分布状况得到了改善，使根尖表皮、皮层、和中柱细胞内Na~+、Cl~-X-射线峰显著降低，而K~+峰提高，使Na~+、Cl~-在整个根横断面上均匀分布，从而缓解盐分离子对金丝小枣的毒害作用。第五，硅对盐胁迫下金丝小枣的超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽过氧化物酶(GSH-Px)酶活性也产生了显著的影响，SOD、GSH-Px酶活性随着盐浓度的增加而增加，POD酶活性在盐浓度0.25％时活性升高，在盐浓度0.4％时活性略有下降，加硅后均维持了较高的SOD、POD、GSH-Px酶活性，从而削弱了活性氧对细胞膜的伤害。第六，盐胁迫下，金丝小枣叶游离态腐胺酸(f-put)含量下降，游离态亚精胺(f-spd)和游离态精胺(f-spm)以及高氯酸不溶性共价结合态多胺(PISCC-Pas)上升，加硅后，金丝小枣叶f-put含量上升，并促进了金丝小枣叶f-put含量向f-spd和f-spm以及高氯酸可溶性共价结合态多胺(PSCC-Pas)和PISCC-PAs转化，一方面增加了细胞的渗透调节能力，解除了f-put毒害作用，另一方面多胺以共价形式和蛋白质分子结合后，既可以调节蛋白质的生物功能，又可以稳定蛋白质的空间结构，延缓盐胁迫下蛋白质的降解反应。更多还原

【Abstract】 The soil of salt and alkali is one of the key stress factors inhibiting survival rate, growth,fruit yield and quality of Ziziphus jujuba Mill. The research on salt tolerance and controltechnology of jujube is very little in world wide. The availability of silicon in soils for plants isusually low though it is the second abundant element in soils. The research on physiologicalfunction of silicon for plants has been recently focused on.The main object of this study was focused on the relation between silicon and salttolerance of Z.jujuba cv.jinsixiaozao and their mechanism. The test material was 1-years oldgrafting seedlings. X-ray electron probe microanalysis, ultra-structure observation and analysis,High Performance Liquid Chromatography(HPLC)and other scientific methods were used torelease the secretary. The research involved the ultra-structure of cell, the distribution of ionmicro field, the forms and content of Polyamines, the absorption and allocation of mineralelement, the activity of various types of enzyme, etc. The main results of the research werepresented as follows.Firstly, with the increase of soil salt content, the growth of stem and root and the totalbiomass of Z.jujuba cv.jinsixiaozao were all decreased. If the content of salt is little than 0.3%,with the addition of the fertilizer of silicon, the indications above were enhanced; if the contentof salt is 0.4%, with the fertilizer of silicon, the indications above were enhanced appreciably.The effect of the indications was best when the silicon content was 0.5‰.Secondly, when the content ration of salt is 0.2%, the cell of Z.jujuba cv.jinsixiaozao didn’tappear phenomena of the plasmolysis. Nevertheless, with the salt stress of the salt contentration is 0.3% and 0.4%,the leaf ultra-structure was changed remarkably. The double membraneof chloroplast was broken off. The stroma lamella structure was completely destroyed. Thestarch grains were decreased, with silicon fertilizer, it alleviated the damage of salt stress on thecell ultra-structure of Z.jujuba cv.jinsixiaozao, kept the integrity of chloroplast lamella structure,decreased the dilapidation of membrane system, delayed the senescence and disorganization ofchloroplast. This result was shown that, under salt stress, with silicon fertilizer, thephotosynthesis function was protected and the capability of osmotic adjustment was enhanced.Thirdly, with the increasing of the content ration of NaCl, the content ration of the ion ofNa and Cl and the ratio between the ion Na and Cl in the stem, root and leaf of Z.jujubacv.jinsixiaozao was went up remarkably, but the content ration of the ion of K was fall. Withsilicon fertilizer, the content ration of the ion of Na and Cl and the ratio between the ion Na andCl in the stem, root and leaf of Z.jujuba cv.jinsixiaozao was fall, but the ion of K was went up.This result was shown that, under salt stress, silicon kept the ion balance in the plants and theion homeostasis in photosynthetic cells. Fourthly, with silicon fertilizer, the situation of micro-domain distribution of Z.jujubacv.jinsixiaozao under salt stress had been improved. The X-ray peak value of the content of theion of Na and the ion of Cl in the epidermis、cortex and stele cell of root descended significantly,but this of the ion of K ascended. It caused the uniform distribution of the ion of Na and Cl inthe transect of root, so the damage of salt on Z.jujuba cv.jinsixiaozao was consequentlyalleviated.Fifthly, salt stress had the effects of silicon on changes of glutathione peroxidase (GSH-Px)and superoxide dismatase (SOD) and peroxidase (POD) activity of Zizyphus jujube cv.Jinsi-xiaozao. SOD and GSH-Px activity increased with increasing salinity under salinityconditions, POD activity increased under 0.25% NaCl and decreased under 0.4% NaCl. Withsilicon fertilizer, SOD, POD and GSH-Px activity was maintenance. Accordingly, it alleviatedthe damage of membrane of active oxygen.Sixthly, under salt stress, the content of f-put was fall, but the content of f-spd, f-spm andPISCC-PAs were gone up. With silicon fertilizer, the content of f-put in the leaf was risen andthe transformation between the content of f-put and the content of f-spd, f-spm PSCC-Pas andPISCC-PAs were promoted. It increased the capability of the cell osmotic adjustment andrelieved the damage of f-put. With the combination of Polyamines and Protein molecular incovalence type, it could adjust the biologic function of protein and could stabilitate the spacestructure of protein, delay the decomposition reactivity of protein under salt stress.更多还原