花生Cu/Zn-SOD活性响应干旱胁迫的分子机制研究

Peanut is an important oil crop in China. Drought stress causes most serious harm to peanut production.Superoxide dismutase is key enzyme in resisting oxidative damage caused by drought stress. Superoxide dismutase activity is closely related to drought resistance. Most of the superoxide dismutase in peanut is Cu/Zn superoxide dismutase. There are big differences among germplasms and drought stresses in peanut. Our recent research showed that there is no difference in gene structure among most peanut germplasms from four types of peanut (A. hypogaea L.). The changing mechanism of SOD activity has not been reported in peanut at the gene transcription level. This project plans to select peanut germplasms with different drought resistance and different SOD activity. And let them exposed to different degree and sustaining time of drought stress. Using NBT method to determine Cu/Zn superoxide dismutase activity and using RT-PCR method to determine gene expressive quantity. And then relationship between the Cu/Zn superoxide dismutase activity and gene expressive quantity of different treatments be analyzed. The purpose is to reveal the regulation mechanism of changes in Cu/Zn superoxide dismutase activity at gene transcription level, which has an important significance in study on the regulation pathway of Cu/Zn superoxide dismutase activity and drought resistance mechanism. And it also has reference value for development of drought resistant cultivation and screening of excellent germplasm in peanut.

花生是重要油料作物，干旱是影响花生生产的主要逆境因子。超氧化物歧化酶(SOD)是抵御干旱引起的活性氧氧化损伤的关键酶，SOD活性与抗旱性密切相关。花生中起主要作用的是Cu/Zn-SOD。花生种质间、干旱处理间SOD活性具有较大差异，而本课题组近期研究了花生四大类型代表种质，没发现种质间Cu/Zn-SOD结构基因有差异。花生SOD基因转录水平调控SOD活性的研究未见报道。本项目拟选用不同抗旱性及不同SOD活性的花生种质，进行不同胁迫程度、不同胁迫持续时间的干旱处理，测定叶片Cu/Zn-SOD活性，通过荧光定量PCR检测Cu/Zn-SOD基因表达量，分析不同种质、不同干旱胁迫下Cu/Zn-SOD活性变化和基因表达量的关系，揭示花生Cu/Zn-SOD活性变化在基因转录水平的调控机制。对探讨花生SOD活性的调控途径及抗旱机理具有重要意义，对研发抗旱栽培措施和筛选抗旱种质亦有参考价值。

花生是重要油料作物，干旱是影响花生生产的主要逆境因子。超氧化物歧化酶(SOD)是抵御干旱引起的活性氧氧化损伤的关键酶，SOD活性与抗旱性密切相关。本项目选用不同抗旱性及不同SOD 活性的花生种质， 进行不同胁迫程度和不同胁迫持续时间处理，分析不同种质、不同干旱胁迫下SOD 活性变化和基因表达量的关系，揭示花生SOD 活性变化在基因转录水平的调控机制。主要研究结果如下： .（1）干旱胁迫下不同品种/种质SOD基因转录水平表达量的分析.品种间SOD活性与基因转录水平的表达量呈极显著正相关；干旱胁迫下基因转录水平的表达量与品种抗旱性呈极显著正相关，基因转录水平的表达量可作为品种抗旱性机制的鉴定评价指标。.（2）不同程度干旱胁迫SOD基因表达量及酶活性变化规律及机制.随胁迫程度增加SOD基因转录水平相对表达量呈先增加再降低的趋势；中度干旱胁迫时相对表达量均达到峰值并趋于稳定。SOD酶的活性，随着干旱胁迫程度的增加，呈现先升高后降低的趋势。不同品种不同干旱胁迫程度变化规律存在差异。轻度干旱胁迫下5个品种SOD酶活性均有不同程度的升高，而中度干旱胁迫下仅抗旱性强的山花11号、农大818、如皋西洋生3个品种的SOD酶活性升高，抗旱性弱的白沙1016和ICG6848则降低；重度干旱下所有品种的SOD酶活性均降低。SOD酶活性、基因表达量均与品种的抗旱性显著正相关。.（3)不同胁迫持续时间下花生SOD基因在品种间的表达差异分析.PEG胁迫下不同抗旱性品种叶片SOD活性及AhCSD2基因转录水平表达量差异极显著；抗旱品种山花11号和冀花4号AhCSD2转录水平表达量和SOD活性极显著高于不抗旱品种白沙1016和Krapt.st.16；SOD基因转录水平和SOD活性分别于处理12 h和24 h时达到峰值，且呈极显著正相关；结果表明花生SOD活性受基因转录水平的调控。.（4）花生单叶Cu/Zn-SOD 基因表达量和酶活性的变化动态.花生叶片生长过程中SOD活性呈现先上升后降低的趋势，但干旱胁迫后SOD的变化品种间有较大差异，不同时间干旱胁迫均导致山花11号叶片SOD活性增加，而白沙1016在干旱前期SOD活性增加，30天以后SOD活性比对照的降低。SOD基因表达量呈现基本一致的规律。表明，叶片生长过程中，SOD活性受基因转录水平的调控。