棉花GhBOP1对蕾铃离层形成发育的调控机理研究

The shedding rate of cotton buds and bolls is above 60 percentage. The yield of cotton fibre should be significantly increased if the cotton buds and bolls do not or less fall from the plants. The abscission zone (AZ) forms in the site where the shedding takes place. Typically, the AZs consist of several layers of cytoplasmically condensed cells, which are anatomically divergent from the adjacent cells. The AZs can be triggered by both developmental signals and external stimuli. The GhBOP1 gene has been identified from Gossypium hirsutum , and of which protein sequence and dormains has been deduced. The expression of GhBOP1 gene is higher in AZs of cotton buds and bolls than other organs by qPCR analysis. The GhBOP1 can interact with TGA transcriptional factor and other proteins according to its protein components by program prediction. The four types of transgenic plants, including overexpression of intact and truncated GhBOP1 gene, antisense expression, and RNAi, will be developed. The function of GhBOP1 can be exhibited through the comparison of phenotype and anatomy of AZ of transgenic plants with wild type. And, according to the GUS stain and GFP subcellular localization analyis, the GhBOP1 characterization can be exhibited. The protein interaction analysis should reveal whether GhBOP1 is dimerism and interacts with TGA transcription factor or other protein to regulate the cell differentiation of AZ according to the results of Yeast two-hybrid, firefly luciferase complementation imaging and in vitro pull-down assays. After all, the molecular mechanism of GhBOP1 regulation to abscission cell differentiation must be exposed through this study. While the pathways of signal and metabolic concerning the GhBOP1 are shown, the transgenic plants with lower shedding rate of buds and bolls should be developed by molecular design breeding.

棉花蕾铃生理脱落率在60%以上，降低其脱落可以使棉花产量大幅度上升。蕾铃脱落通常在其柄基部先形成离层，离层细胞从分化、生长发育到凋亡是一个复杂过程，有许多信号传递和代谢途径基因参与。我们已从棉花中分离一个参与离层形成的调控蛋白GhBOP1，初步研究表明其在离层中特异表达，可能通过与TGA转录因子或其它蛋白互作来调控离层发育相关基因的表达。本项目通过培育过量和抑制表达GhBOP1的转基因棉花株系并与野生型进行比较研究，分析该蛋白在棉花蕾铃离层细胞分化等时期的功能，观察其超微结构，了解细胞形态和排列上变化，进一步验证GhBOP1对离层形成的调控功能。同时通过蛋白互作试验明确GhBOP1的domain组成及功能、二聚体结合和TGA等蛋白的互作关系，结合该蛋白的组织特异性GUS染色和GFP亚细胞定位等试验结果，揭示GhBOP1在棉花蕾铃离层形成调控的分子机理，为棉花高产育种提供理论和物质基础。

棉花的结铃性是决定棉花产量的最重要因素之一，然而棉花蕾铃脱落率很高。因此提高棉花结铃性是当前高产育种中主要解决的问题之一。本研究旨在通过对棉花离层分化、发育和形成的分析，阐明一个棉花离层分化的调控基因GhBOP1的功能和分子机制。我们从陆地棉中分离该基因，通过生物信息学分析表明GhBOP1蛋白序列具有较强的保守性BTB和ANK结构域，进化分析表明该蛋白氨基酸序列与许多植物的同源蛋白相似程度很高，进化较慢。利用qPCR进行组织特异性表达分析表明，GhBOP1在根、茎、叶、花等组织器官中有少量表达，在离层中为优势表达，为叶片表达水平的20倍。利用病毒诱导基因沉默技术干涉棉花GhBOP1基因的表达，结果表明在盐胁迫处理下，对照植株叶片脱落，而该基因沉默植株叶片仍然没有脱落。这个初步研究结果表明GhBOP1基因在离层中优势表达，同时对离层的形成具有调控功能。至于该基因对离层形成的调控分子机制有待于进一步研究。