黄瓜生长素合成基因CsYUC8调控高温早衰的分子机制

High temperature caused cucumber early senescence, which led to decrease of cucumber quality and production. Auxin was an important phytohormone for plants to response to high temperature and regulate senescence. Our previous study shown that there was a significant difference of the early senescence phenotype between thermotolerance and thermosensitive cucumber plant under high temperature, and it was correlated with the content of auxin. Exogenous application of auxin could delay the early senescence phenotype caused by high temperature. But which gene involved in auxin mediates early senescence under high temperature in cucumber is unclear. Our recent transcriptome of thermotolerance and thermosensitive cucumber after high temperature stress analysis shown that auxin biosynthesis gene CsYUC8 was significantly up-regulated by high temperature in thermotolerance cucumber. We speculated that CsYUC8 gene may be a key factor in the regulation of early senescence caused by high temperature in cucumber. Functional studies have preliminarily confirmed that overexpression of CsYUC8 in wildtype Arabidopsis thaliana can improve heat resistance. In this study, the function and expression level of CsYUC8 will be identified, the effection of CsYUC8 gene on early senescence caused by high temperature will be analyzed. The upstream interaction target gene and interaction protein of CsYUC8 will be screened and identified through yeast-one-hybridization, Effector and Reporters system, yeast-two-hybridization and BiFC. The results obtained in this project will reveal the role and molecular mechanism of CsYUC8 in early senescence under high temperature, and provide the theory basis for molecular breeding for vegetable cultivars with high temperature resistance.

高温逆境引起黄瓜早衰，导致黄瓜品质和产量下降。研究表明生长素是植物响应高温和调控衰老的重要激素。前期研究基础表明，高温下热敏型和耐热型黄瓜早衰差异明显，且与生长素含量有相关性。外源施用生长素延缓高温引起的黄瓜早衰。但是，究竟哪个基因介导生长素响应黄瓜引起高温早衰尚不清楚。转录组分析发现，黄瓜生长素合成基因CsYUC8在耐热型黄瓜受高温诱导上调表达。我们推断CsYUC8基因可能是参与调控黄瓜高温早衰的关键因子。功能研究初步证实拟南芥中超表达该基因能够提高耐热性。因此，本项目以CsYUC8为切入点，对该基因进行表达特性和功能鉴定研究；通过高温胁迫研究其在高温早衰中的作用；开展酵母单杂交、Effector和Reporter系统、酵母双杂交和BiFC研究，鉴定上游调控转录因子，以及与CsYUC8互作蛋白。本项目实施可揭示CsYUC8在高温早衰的作用以及分子机制，为蔬菜抗逆分子机制研究提供理论依据。

高温逆境引起黄瓜早衰，导致黄瓜品质和产量下降。研究表明生长素是植物响应高温和调控衰老的重要激素。前期研究基础表明，高温下热敏型和耐热型黄瓜早衰差异明显，且与生长素含量有相关性。但是，究竟哪个基因介导生长素响应黄瓜引起高温早衰尚不清楚。本项目以黄瓜耐热“TT”和热敏“TS”黄瓜为研究材料，对黄瓜生长素合成基因CsYUC8响应高温的功能和调控机制进行了研究。对野生型拟南芥外源喷施生长素后高温处理，结果表明低浓度的生长素能够提高拟南芥的光合系统稳定性，增强耐热能力，延缓衰老。对黄瓜子叶期幼苗和五叶期植株外源喷施生长素后高温处理，结果表明低浓度外源生长素能够提高黄瓜的耐热性。通过构建CsYUC8超表达和CRISPR-Cas9敲除载体，分别对“TS”和“TT”黄瓜进行遗传转化，发现超表达CsYUC8提高了拟南芥的耐弱光和耐热性；黄瓜Csyuc8突变体光合稳定性降低，耐热性降低，延缓黄瓜衰老。对CsYUC8启动子构建酵母单杂交载体，与黄瓜cDNA文库进行互作基因筛选，初步发现CsPIF1、CsHAT22和CsPIF4等蛋白能结合到CsYUC8的启动子上。进一步通过酵母单杂交和双荧光素酶系统验证出CsHAT22抑制CsYUC8的启动子转录活性，CsPIF1增强CsYUC8的启动子转录活性。表达分析发现CsPIF1和CsHAT22与CsYUC8表达模式相似，表明CsPIF1和CsHAT22通过动态调节CsYUC8来调控黄瓜耐热性。本项目阐明了内源生长素合成基因CsYUC8参与黄瓜高温的分子通路，以及生长素提高黄瓜耐热性，为黄瓜耐热分子育种提供了理论基础，也可为外源物质提高植物耐热性提供了参考。

内容获取失败，请点击重试