温度敏感香蕉叶绿素降解基因的启动子活性分析与转录因子筛选

Banana is one of the major fruits in south China. Green ripening, induced by high temperature, limits the transportation and marketing of the fruit in summmer in this area, and reduces appearance quality and the values of the fruit. Our previous study indicated that, both fruit degreening and chlorophyll degradation in the peel, are sensitive to the temperature change within the range of the summer ambient temperatures. Green riping of bananas is considered as an abnormal phenomina in plant kindom, and may serve as a wonderful experimental system for the study of the regulation of chlorophyll degradation. The present project aims to explore the regulation mechanism of amibient temperature on chlorophyll degradation related gene expression in banana fruit. The promoters of the key chlorophyll degradation genes, such as SGR and PaO will be cloned and subjected for activity assay to confrim their temperature sensitive natures. The temperature sensitive cis-elements within the promoters will be identified and applied as biat sequences for yeast one hybridization screening for the interacted transcription factors. Further more, the putative promoter-dependent gene expression responsible to temperature of chlorophyll degradation will be tested by gene transformation in stay green tomato(gf). The results of this project will be helpful to understand the regulation of chlorophyll degradation in higher plants and to explore new postharvest treatments to control color qualities of fruits and vegestables.

香蕉果实青皮熟现象是限制华南地区高温季节香蕉北运、后熟转黄及商品价值的主要因素。大量研究表明，香蕉青皮熟及叶绿素降解关键基因对常温范围内的温度变化非常敏感，是植物界叶绿素降解的特殊现象，为研究叶绿素降解调控机制提供了极佳材料。本项目拟在前期工作基础上，克隆香蕉果皮叶绿素降解关键基因的全长启动子，通过分析启动子的活性，探明启动子的温度敏感特性及鉴别启动子的温度敏感作用元件；筛选与温度敏感型启动子相互作用的转录因子，探讨植物依赖于温度的叶绿素降解关键基因的转录调控模式；最后通过转基因技术，在滞绿番茄果实中进一步验证温度敏感型启动子调控叶绿素降解的分子机制。本项目研究成果不但可为果蔬采后色泽品质控制新措施的探索提供理论依据，也有助于人们深入理解植物叶绿素降解途径的调控机制，因此本项目的研究具有重要的理论价值和实践意义。

香蕉果实青皮熟现象是限制华南地区高温季节香蕉北运、后熟转黄及商品价值的主要因素。香蕉青皮熟及叶绿素降解关键基因对常温范围内的温度变化非常敏感，是植物界叶绿素降解的特殊现象。本项目通过8组不同的后熟温度组合处理，分析了不同阶段的温度对果皮叶绿素降解的影响。结果表明，前3天尤其跃变期（第2-3天）的温度对果皮颜色的形成至关重要。克隆了香蕉果皮叶绿素降解关键基因的全长启动子，通过分析启动子的活性，探明了启动子的温度敏感特性及鉴别启动子的温度敏感作用元件；筛选了与温度敏感型启动子相互作用的转录因子，探讨植物依赖于温度的叶绿素降解关键基因的转录调控模式。此外，还通过RNA-Seq 构建了20˚C和30˚C下后熟香蕉果皮转录组差异表达谱，成功构建了对照、乙烯处理后20˚C和乙烯处理后30˚C果皮蛋白质组差异表达谱。共鉴定到1679个蛋白，两个生物重复间共同蛋白个数为416个，其中显著差异变化蛋白共91个。本项目研究成果不但为果蔬采后色泽品质控制新措施的探索提供了理论依据，也有助于人们深入理解植物叶绿素降解途径的调控机制。