葡萄细胞分裂素响应调节因子VvRR2在坐果与幼果发育中的功能分析

Fruit set and young fruit growth development process determines the fruit yield and quality. Cytokinins are widely used in fruit production, mainly used to promote the fruit set and regulate the fruit growth and development. In our previous study, a key transcription factor VvRR2 in cytokinin signal transduction pathway was cloned in grapevine. Sublocalization experiment showed VvRR2 mainly localized in nucleus; transcriptional activity analysis showed VvRR2 had activity in yeast. By screening the yeast two hybrid expression cDNA library, 31 positive clones were obtained, of which two clones encoded a same F-box protein, named as VvRRIF (VvRR2 interaction F-box). This study intends to further study the expression characteristics of VvRR2 in grapevine fruit set and young fruit development, and analyze the role of VvRR2 in fruit set and young fruit development process. We also plan to identify the interaction relationship between VvRR2 and VvRRIF, and whether the interaction between them is involved in grapevine fruit set and young fruit development process. These study results can not only clear the biological function of VvRR2 in the process of grapevine fruit set and young fruit development, provide a theoretical basis for molecular mechanism analysis of fruit set and young fruit development. It also provides the reference basis for the application of cytokinins in fruit production practice.

果实坐果和幼果生长发育过程决定了果实的产量和品质。细胞分裂素在果树生产实践中广泛用于促进坐果和调节果实生长发育。前期，本课题组在葡萄中克隆了细胞分裂素信号转导途径中的关键转录因子VvRR2，初步鉴定了VvRR2主要定位在细胞核，在酵母细胞中具有转录激活活性，通过酵母双杂交筛选得到31个阳性克隆，其中有两个克隆编码同一个F-box蛋白，命名为VvRRIF（VvRR2 interaction F-box）。本项目拟进一步研究VvRR2在葡萄坐果与幼果发育中的表达特性，分析VvRR2在葡萄坐果与幼果发育过程中的作用，同时研究VvRR2与VvRRIF的相互作用关系及其二者是否参与葡萄坐果与幼果发育过程中。这些研究成果不仅可以明确VvRR2在葡萄坐果与幼果发育过程中的生物学功能，为解析果实坐果与幼果发育的分子机制提供理论基础，同时也为细胞分裂素在果树生产实践中的应用提供参考依据。

细胞分裂素在生产中主要用来促进葡萄坐果和幼果发育，但是其分子机制还不清楚。本项目采用基因表达、体外蛋白降解等技术研究了VvRR2基因介导细胞分裂素信号调控葡萄坐果与幼果发育。VvRR2和VvRRIF基因可以响应外源细胞分裂素及其抑制剂CHX；酵母双杂交和BiFC试验结果显示VvRR2和VvRRIF可以相互作用，VvRRIF作用在VvRR2的上游，VvRRIF的表达可以导致VvRR2蛋白的降解，细胞分裂素可以促进VvRR2蛋白的降解；转基因番茄植株的坐果率显著高于野生型，过量表达VvRR2增加了转基因植株中的细胞分裂素含量，同时影响转基因植株中种子的发育。这些研究结果不仅明确了VvRR2在葡萄坐果与幼果发育过程中的生物学功能，为解析果实坐果与幼果发育的分子机制提供理论基础，同时也为细胞分裂素在果树生产实践中的应用提供参考依据。