番茄油菜素内酯受体SlBRI1磷酸化对果实发育成熟的影响

The BRASSINOSTEROID INSENSITIVE1 (BRI1) is the BR receptor kinase, which initiates the BR signal transduction through its phosphorylation. Phosphorylations of different sites play critical roles in BRI1 kinase activity and have distinct biological functions. Tomato serves as a model plant for fleshy berry in horticulture plant molecular biology research. To identify the unique roles of SlBRI1 phosphorylation sites in fruit development regulation, site-directed mutagenesis of critical phosphorylation sites were constructed and transformed into weak mutant slbri1. Analyses of kinase activity, expression level as well as some physiological and biochemical tests about fruit such as HPLC and paraffin section were used to identify the regulatory effects of SlBRI1 in fruit development and ripening. Furthermore, the regulatory role of phosphorylation sites in SlBRI1 biological functions will be clarified by making comparison of fruit developmental difference between transgenic lines expressing full-length SlBRI1 constructs and those harboring SlBRI1 site-directed mutant constructs. Finally, our study may provide molecular basis to achieve controlling the quality of fruit production precisely via modifying phosphorylation sites, as well as lay theoretical foundation for creating better-quality and higher-yielding crop varieties.

油菜素内酯受体BRI1与油菜素内酯（BR）结合后，通过磷酸化位点的磷酸化使受体激活转导BR信号。BRI1不同磷酸化位点的磷酸化影响其激酶活性并具有不同的生物学功能。番茄是研究浆果类发育的模式植物，为了确定SlBRI1磷酸化位点在果实发育成熟过程中的调控功能，本项目以番茄SlBRI1弱突变体slbri1植株为材料，通过对SlBRI1关键磷酸化位点定点突变，获得SlBRI1及其各个磷酸化位点突变后的转基因植株。根据SlBRI1表达丰度及活性，结合液相色谱、石蜡切片等果实产量品质相关生理指标分析方法，阐明SlBRI1对番茄果实发育成熟的调控作用。同时，通过对比SlBRI1及其磷酸化位点突变后的转基因植株的果实生长发育差异，揭示磷酸化位点对SlBRI1调控番茄果实发育成熟功能的影响。本项目为利用基因内磷酸化位点实现对果实产量品质精准调控提供分子基础，同时为创建高产优质的作物育种材料奠定理论依据。

油菜素内酯受体BRI1与油菜素内酯（BR）结合后，通过磷酸化位点的磷酸化使受体激活转导BR信号。BRI1不同磷酸化位点的磷酸化影响其激酶活性并具有不同的生物学功能。本项目首先以番茄MicroTom为研究材料，创建番茄油菜素内酯受体SlBRI1超量转基因植株，并对其进行果实产量和品质相关性状的生理生化检测，揭示SlBRI1在番茄果实发育成熟过程中的生物学功能。在此研究基础上，本项目又进一步对SlBRI1进行定点突变，并遗传转化至番茄SlBRI1弱突变体cu3-abs1中，创建了多个模拟磷酸化和非磷酸化的磷酸化位点突变体。通过对比SlBRI1及其磷酸化位点突变后的转基因植株的果实生长发育差异，揭示磷酸化位点对SlBRI1调控番茄果实发育成熟功能的影响。目前已鉴定到对SlBRI1生物学功能具有重要调控功能及农艺学潜在价值的磷酸化位点Ser1040和Thr1050。本项目为利用基因内磷酸化位点实现对果实产量品质精准调控提供分子基础，同时为创建高产优质的作物育种材料奠定理论依据。