新型植物生长调节剂五谷丰素早期应答基因及调控代谢通路研究

Wugufengin, isolated from a novel actinomycete, was demonstrated to show significant effect on improving crop yield and quality, and exhibited a dual function combining the bioactivity of auxin and cytokinin to promote the growth of root and shoot. It acted as a new plant growth regulator promoting plant growth and enhancing plant resistance to diseases at the same time. Arabidopsis thaliana treated with Wugufengin display obvious changes in expression level of marker genes involved in plant growth hormones (auxin and cytokinin) and plant defense hormones (jasmonic acid and salicylic acid) signaling pathways. The Wugufengin-treated plants performed distinctly different phenotypes comparing to the ones processed with auxin indole-3-acetic acid and cytokinin zeatin. Additionally, Wugufengin didn’t act on the target molecule of cytokinin, CRE1, AHK2 or AHK3, along with the target molecule of auxin, tir1-1. It implied that a new signal transduction pathway was employed by Wugufengin and the plant growth and resistance response to pathogens were regulated using a new molecular mechanism. This project plans to sequence transcriptome, proteome and metabolome of A. thaliana and Oryza sativa with obvious different phenotypes in early phase and different growth stages after the treatment of Wugufengin. By using multi-omics analysis and function validation of the screened key genes related to early response and core genes responsible for regulating metabolic pathways, we attempted to identify the early-phase response genes of Wugufengin and elucidate the regulating metabolic pathways. These findings will ultimately provide important breakthrough to decipher the action mechanism and signal transduction pathway of Wugufengin.

五谷丰素是从新放线菌中分离发现能显著提高作物产量，改善粮食品质，有植物生长素和细胞分裂素促进植物根、芽生长的双重特性，且抗植物病害，为罕见能同时促进植物生长和增强植物抗病的新型植物生长调节剂。五谷丰素处理拟南芥后的生长激素类生长素、细胞分裂素，以及防御激素类的茉莉酸、水杨酸信号途径中的标记基因表达量发生明显变化，但与生长素吲哚乙酸、细胞分裂素玉米素等作用于植物的表型明显不同，也不作用于细胞分裂素的3个作用靶标分子和植物生长素的靶标分子。五谷丰素存在新的信号转导途径，以新的分子机制调控植物生长和抗病。拟测定五谷丰素作用早期和使用后不同生长期表型差异大的拟南芥、水稻转录组、蛋白组和代谢组，多组学联合分析，并结合分析筛选出的早期应答关键基因及调控代谢通路中核心基因的验证与功能确证，探明五谷丰素早期应答基因，明确调控代谢通路，以认知五谷丰素作用基础机制和为深入探索五谷丰素信号转导途径寻找到突破口。

五谷丰素是一种能促进水稻种子萌发，根和芽生长及早花早熟的新型植物生长调节剂。通过比较转录组学分析发现其不能激活赤霉素、细胞分裂素、生长素及油菜素内酯早期响应基因。差异基因分析显示参与植物生长发育的WRKY与SAUR家族转录因子被显著调控。本研究对五谷丰素的促拟南芥早花和水稻种子萌发的分子机制进行了研究。过表达WRKY41 （35S:WRKY41）和WRKY53 （35S:WRKY53）株系均表现出早花表型，相反，谷维菌素处理的WRKY41/WRKY53双敲除株并没有表现出早花表型。基因表达分析表明，在谷维菌素处理的野生型和35S:WRKY41中，开花时间整合基因SOC1和花分生组织特征基因LFY的转录水平升高，而在WRKY41/WRKY53双敲除株的转录水平下降。体外和体内的实验表明WRKY41与WRKY53均能够与SOC1与LFY的启动子区域结合，并在35S:WRKY41株系分别敲除SOC1与LFY后发现35S:WRKY41的早花表型消失。以上结果表明WRKY41和WRKY53介导了五谷丰素诱导的拟南芥早花。同时，本研究发现五谷丰素处理的水稻种子中的α-淀粉酶基因显著上调。免疫印迹试验显示五谷丰素可诱导阻碍植物生长发育的关键调控元件DELLA蛋白的泛素化降解。表型分析显示五谷丰素失去对DELLA突变体植株的促生作用，但仍然能促进赤霉素突变体种子萌发。以上结果表明五谷丰素是通过诱导DELLA降解促进种子萌发，但是不依赖赤霉素受体途径。