SAMDC调控多胺参与棉花抗逆分子机制研究

Cotton was an important cash crop, low temperature, drought and salinity stress seriously influenced yeild and quanlity of cotton fibre. Many results suggested polyamines commonly involved in plant growth and development, and played important roles in response to abiotic stress. In this study, we cloned the cDNA sequence of SAMDC genes in cotton, analyzed the expression patternes of SAMDC in different tissues and stress treatments by realtime-PCR. Overexpression and RNAi vectors were constructed by gateway technology, and transformated into cotton mediated by Agrobacterium tumefaciens, transformated offsprings(including overexpression and RNAi) were identified. The effects of SAMDC gene during cotton growth and development were dectected in contorl(untransformated) and transformated plants treated with different stresses. On the other hand, the content of H2O2, NO, ABA and polyamines(putrescine, spermidine, spermine) were detected, gene expressions of SAMDC and transcription factors related abiotic stress resistance were detected in different stress treatments. Correlation analysis between physiological indexes, genes expression, and physiological indexes and genes expression were analyzed.The potential metabolic pathway was identified by gene expression of certain stress resistance related genes.Together with these results, molecular mechanism of SAMDC would be clarified, and provided a new reflection to stress resistance breeding in cotton.

棉花是重要的经济作物，低温、干旱、盐碱等多种非生物胁迫严重影响棉花产量和品质，大量研究表明多胺调节植物生长和发育，在抵御各种非生物胁迫过程中发挥重要作用。本项目拟在克隆棉花多胺代谢关键酶SAMDC基因全长cDNA序列的基础上，利用Realtime-PCR技术分析它在不同组织和不同胁迫条件下的表达特征；构建植物超表达和RNAi载体转化棉花，比较转基因株系和对照植株对不同胁迫处理的反应。采集不同胁迫条件下不同处理时间样本，进行H2O2、NO、ABA和多胺（腐胺、亚精胺、精胺）含量测定，同时分析 抗逆相关转录因子表达情况；分析各项生理指标之间、基因表达之间以及生理指标和基因表达之间的相关性，明确多胺、信号分子和转录因子之间的关系和多胺参与抗逆的可能途径，进而对不同途径中的相关基因进行表达分析验证，解析SAMDC调控棉花多胺参与抵御非生物胁迫的可能机制，为棉花抗逆育种研究提供新思路。

棉花是重要的经济作物，低温、干旱、盐碱等多种非生物胁迫严重影响棉花产量和品质。大量研究表明S-腺苷甲硫氨酸脱羧酶（SAMDC）基因通过参与多胺代谢调节植物生长和发育，参与抵御各种非生物胁迫过程。本项目克隆获得3个棉花多胺合成关键SAMDC基因，利用Realtime-PCR技术分析不同组织和不同胁迫条件下的表达特征；GhSAMDC2在茎中表达相对较高，随着纤维发育表达量不断增加，在纤维发育后期表达量达到最高；GhSAMDC2受低温和干旱胁迫诱导最强烈，GhSAMDC3响应盐胁迫显著，GhSAMDC4受ABA诱导强烈。构建植物超表达载体转化棉花和拟南芥，GhSAMDC2，3均得到至少5 株阳性转基因棉花植株。选择3个转GhSAMDC3拟南芥株系进行NaCl胁迫处理，结果表明200 mM NaCl处理下，转基因拟南芥种子萌发率显著高于野生型；推测GhSAMDC3基因显著提高了盐胁迫下拟南芥的种子萌发。用200 mM NaCl处理时GhSAMDC3基因在48h 表达量显著升高；高压液相色谱分析发现转基因拟南芥中亚精胺含量极显著升高。抗盐相关基因表达分析表明，GhSAMDC3基因可能通过多种途径参与了抗盐过程，该结果可为棉花抗逆育种研究提供新思路。

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