棉花耐盐和镉复合胁迫基因型差异及外源GSH缓解盐胁迫的生理机理

摘要

盐害是抑制植物生长和产量的主要环境因素。镉是有毒重金属，近年来，土壤镉污染对食品生产安全已经构成了严重的威胁，潜在地危害着农业和环境。了解镉积累和转移的机制是研究植物修复和可持续农业发展的一个重要方向。本研究探讨了镉与盐害单一或复合胁迫对棉花生长、光合参数、抗氧化代谢和超微结构的影响及基因型差异，同时研究了谷胱甘肽(GSH)对盐(NaCl)胁迫的缓解效应，主要研究结果如下:
　　1.盐与镉复合胁迫对棉花光合特性、抗氧化能力、超微结构和营养元素含量的影响及基因型差异
　　水培试验，比较研究了镉(Cd)和盐(NaCl)单独或复合(Cd+ Na)胁迫对两个耐盐性不同的棉花基因型中棉41（盐敏感）和中9806（耐盐）生长、光合特性、脂质过氧化、抗氧化酶活性、镉和钠含量以及根和叶片超微结构的影响及基因型差异，结果表明，镉和盐胁迫抑制棉花生长，降低光合速率和叶绿素含量;镉胁迫下，其中盐敏感基因型中棉41较耐盐中9806受抑制更严重。此外，单独或复合的盐害和镉胁迫诱导中棉41丙二醛(MDA)积累，而镉与盐害单一处理5和10d后中9806的MDA含量没有显着差异，但复合胁迫下MDA显著增加;镉胁迫诱导POD和CAT的活性增加，但镉胁迫5d后抑制CAT酶活性;Cd、NaCl和Cd+NaCl胁迫对SOD和APX酶活性的影响表现基因型和时间依赖性。植株Na和Cd的浓度在两种基因型的棉花中增加，而且在中棉41中增加更多;Ca和Mg浓度下降，在中棉41中下降更多。另外，Cd和盐胁迫诱导叶绿体超微结构的变化，使基质片层肿胀，类囊体膜松散，增加了嗜锇的质体的数量;在根细胞中，由核膜裂缝开始降解。
　　2.外源GSH缓解棉花盐胁迫的基因型差异
　　以中9806和中棉41为材料进行水培试验，研究了外源GSH对盐胁迫的缓解作用。150mM NaCl胁迫下，植株株高、根长和地上部/地下部干重均显著降低。盐胁迫降低光合作用和叶绿素含量，增加MDA积累;与中9806相比，中棉41降低的更显著。盐胁迫显著增加植株Na浓度，而在中棉41中更高;Ca和Mg浓度在中棉41中均下降，而中9806与对照相比无显著性差异。在150mM NaCl溶液中施用外源GSH(Na+GSH)显著缓解了盐胁迫。与单独盐胁迫(150mM NaCl)相比，Na+GSH增加了根、茎、叶的干/鲜重、光合速率和叶绿素含量，并且缓解了盐胁迫对细胞超微结构的损伤，尤其是在中棉41中。

目录

声明

论文说明

ACKNOWLEDGEMENTS

Contents

Abstract

Abbreviations

摘要

Chapter 1 Literature review

1．1 Uptake and distribution of Cd in the plant

1．2 Effect of Cd on growth

1．3 Effect of cadmium on nutrient uptake and plan-water relationships

1．4 Effect of Cd on metablic processes

1．5 Salinity effects on plants

1．5．1 Effects of salinity on growth

1．5．2 Effects of salinity on photosynthetic pigments

1．5．3 Effects of salinity on ion levels

1．5．4 Effects of salinity on antioxidative enzymes and antioxidants

1．5．5 Effects of salinity on chloroplast ultrastructure

1．6 The role of Glutathione to alleviate salinity stress in plant

1．7 Research objectives

Chapter 2 Genotypic differences in photosynthetic performance，antioxidant capacity，ultrastructure and nutrients in response to combined stress of salinity and Cd in cotton

2．1 Materials and methods

2．1．1 Plant material and growth condition

2．1．2 Growth measurement and metal analysis

2．1．3 Measurement of lipid per oxidation and antioxidant enzyme activites

2．1．4 Measurement of chlorophyll content，chlorophyll fluorescence and photosynthesis parameters

2．1．5 Examination of leaf and root ultrastrcture

2．1．6 Statistic analysis

2．2 Results

2．2．1 Effect of alone or combined stresses of Cd and salinity on growth parameters

2．2．2 Photosynthesis parameters

2．2．3 Chloropyll content and fluorescence parameters of PSII

2．2．4 MDA content and antioxidant enzymes activities

2．2．5 Ultrastructure of chloroplasts and root-cells

2．2．6 Macro and micro element concenntrations

2．3 Discussion

Chapter 3 Genotypic differences in alleviation effects of exogenous GSH on salinity stress in cotton

3．1 Materials and methods

3．1．1 Plant Material and Growth Condition

3．1．2 Growth Measurement and Metal analysis

3．1．3 Measurement of lipid peroxidation and antioxidant enzyme activities

3．1．4 Measurement of chlorophyll content，chlorophyll fluorescence，photosynthesis parameters

3．1．5 Examination of leafand root ultrastrcture

3．1．6 Statistic analysis

3．2 Results

3．2．1 Effect of salt stress and external application of GSH on growth parameters

3．2．2 Effect of salt stress and external application of GSH on photosynthetic parameters

3．2．3 Chlorophyll content and fluorescence

3．2．4 Effect of salt stress and external application of GSH on antioxidant enzyme activities and MDA content

3．2．5 Macro and micro element concentrations

3．2．6 Ultrastructure changes in chloroplasts and root cells

3．3 Discussion

References

Supplementary Tables