SEUSS家族基因在番茄生长发育过程中的功能解析

Agamous is a floral homeotic gene and SEUSS is a negative regulator of it. By participating in auxin signal transduction, SEU plays an important role in plant embryo, flower and root development. However, the downstream target genes and molecular networks remain unknown, and there are few reports about the regulatory function of SEU on fruit development. The previous data shows that SEU has a high transcript level in tomato fruit, and there are significant differences during fruit development, which indicate the SEU maybe play an important role during the fruit development. In order to further analyze the function and regulation mechanism of SEU, this project is mainly based on tomato to realize the following contents: 1) the function of SEU during tomato fruit development will be characterized by transformation with the over-expression vector and RNA interference vector; 2) the differently expressed gene in the transgenic plant and target gene interacted with SEU will be screened by RNAseq, Pull-down and Yeast two hybrid technique. Thus, the regulation network of SEU-downstream target gene-fruit development will be revealed, and the molecular mechanism of tomato growth and development regulated by SEU will be defined. The result is very useful for understanding the function of SEUSS during the tomato fruit development, and novel genetic resources can be provided to improve the quality of fruit via genetic modification. Therefore, this project has theoretical and practical importance.

SEUSS(SEU)是花发育同源异型基因Agamous的负调控因子，可通过参与生长素信号转导调控植物胚胎、花及根的生长发育，但SEU介导生长素信号调控植物发育的下游靶蛋白及网络途径尚不清楚，且关于SEU对果实发育的调控功能鲜有报道。项目组前期研究表明，SEU在番茄果实中表达水平较高，且果实发育不同时期表达量有显著差异，推测SEU对果实形成有重要调控作用。为深入解析SEU在果实生长发育中的功能及分子机制，本项目以番茄为材料，主要完成：1）SEU超表达和RNAi抑制表达载体构建，并通过转基因技术分析SEU对番茄果实发育的调控功能；2）利用RNAseq、Pull-down及酵母双杂交技术筛选转基因植株差异表达基因及SEU互作蛋白，揭示SEU-下游基因-果实形成之间的调控网络。研究结果将解析SEU调控番茄生长发育的分子机制，并可为果实类作物品种改良提供新基因资源，具有重要的理论价值和应用前景。

SEUSS(SEU)是花发育同源异型基因Agamous的负调控因子，可通过参与生长素信号转导调控植物胚胎、花及根的生长发育，但SEU介导生长素信号调控植物发育的下游靶蛋白及网络途径尚不清楚，且关于SEU对果实发育的调控功能鲜有报道。本项目以番茄为材料，通过转基因技术获得SEU突变体植株，利用RNAseq、Pull-down及酵母双杂交技术筛选转基因植株差异表达基因及SEU互作蛋白，揭示SEU-下游基因-果实形成之间的调控网络。通过项目资助取得以下主要成果：1）构建Slseu1、Slseu2、Slseu3及Slseu4超表达和RNAi抑制表达载体，获得了Slseu1、Slseu2、Slseu4抑制表达株T3代纯合子植株并进行表型鉴定；2）研究表明，抑制Slseu2表达后，花形变大，雌蕊及雄蕊的发育异常，且能够显著提高果实坐果率；3）抑制Slseu-4表达对番茄植株发育周期有重要抑制作用，主要表现生根速度慢，开花时间滞后，花期长且花形大，雌蕊及雄蕊发育异常；另外，抑制Slseu-4表达能够提高叶片叶绿素的合成水平，同时延缓果实转色过程，即抑制果实叶绿素的降解及类胡萝卜素途径合成过程；4）外源激素GA处理能有效提高Slseu-4 RNAi转基因植株的高度，对于转基因植株果实表型无影响，推测Slseu-4延迟植株的发育与GA信号通路相关；5）对转基因材料进行RNAseq深度测序，进行聚类分析、差异表达量比较分析以及 GO 和 Pathway 分析；6）ARF及IAA家族基因在野生型及Slseu-4 RNAi植株不同组织间存在表达特异性，Slseu1、Slseu2、Slseu4与ARF蛋白间存在互作；7）Slseu3转基因植株T0代在培养过程中植株表型白化，无法生根，其功能需进一步研究。项目的研究结果为解析番茄果实发育过程提供了可靠的理论支持和新思路，为果实类作物品种改良提供新基因资源，具有重要的理论价值和应用前景。