SHB1 regulates seed development in Arabidopsis

PI：Min NiProposal number：IOS-0919886 Proposal标题：SHB1调控拟南芥种子发育被子植物中的双受精导致二倍体胚胎和三倍体胚乳的形成。在拟南芥中，种子发育经历了胚乳增殖活跃的初始阶段，随后是胚胎快速生长的第二阶段，但以胚乳为代价。由于成熟种子的大小主要是在初始阶段获得的，因此种子的大小受母体胚珠、胚乳和胚胎的生长协调调节。控制种子大小的机制仍然不清楚，但种子构成了人类种群的大部分食物。SHB1基因是拟南芥种子发育的正调控基因，通过调节细胞大小和细胞数量来调节种子发育。功能获得等位基因shb1-D增加种子大小，功能丧失等位基因shb1缩小种子大小。Shb1-D种子大小的增加与胚乳细胞化的时间、合点端胚乳的扩大以及随后的胚胎发育有关。SHB1调控基因MINI3和IKU2的表达，这两个基因分别编码WRKY转录因子和LRR受体激酶。SHB1在体内与MINI3和IKU2启动子结合，并直接与MINI3相互作用。该项目的目标是测试SHB1是否被WRKY转录因子招募为共激活因子，以控制胚乳发育所需的基因表达。不同的细胞、生化和分子方法将被用来研究SHB1与MINI3的相互作用以及SHB1-MINI3相互作用的生物学后果。了解种子大小调节的机制可能会潜在地增加种子产量，并随之而来的是每粒种子产生的蛋白质和油量的增加。这个项目将为本科生、研究生和博士后提供获得重要研究经验的极好机会，最重要的是，培养他们批判性分析和解决科学问题的能力。种子大小是一种产量性状，传统的植物育种在改善这方面的成效有限。大豆和油菜等主要种子作物的种子发育遵循与拟南芥非常相似的途径。提高大粒种子的潜力是显著提高农业产量的最有希望和探索最少的途径之一。

PI: Min NiProposal number: IOS-0919886Proposal Title: "SHB1 regulates seed development in Arabidopsis"Double fertilization in angiosperms leads to the formation of a diploid embryo and a triploid endosperm. In Arabidopsis, seed development undergoes an initial phase of active endosperm proliferation followed by a second phase in which embryo grows rapidly at the expense of the endosperm. Since mature seed size is largely attained during the initial phase, seed size is coordinately regulated by the growth of the maternal ovule, the endosperm, and the embryo. The mechanisms underlying seed size control are still not well understood, yet seeds form the bulk of the diet of human population. The gene SHB1 is a positive regulator of Arabidopsis seed development that operates through regulation of both cell size and cell number. shb1-D, a gain-of-function allele, increases seed size and shb1, a loss-of-function allele, reduces seed size. The increase in seed size of shb1-D is associated with the timing of endosperm cellularization, enlargement of chalazal endosperm, and subsequent embryo development. SHB1 regulates the expression of the genes MINI3 and IKU2, which encode a WRKY transcription factor and an LRR receptor kinase respectively. SHB1 associates with MINI3 and IKU2 promoters in vivo, and directly interacts with MINI3. The goal of this project is to test if SHB1 is recruited as a co-activator by a WRKY transcription factor to control gene expression required for endosperm development. Various cellular, biochemical, and molecular approaches will be used to investigate the interaction of SHB1 with MINI3 and the biological consequence of SHB1-MINI3 interaction. Understanding the mechanisms of seed size regulation has the potential to generate a potential increase in seed yield and a concomitant increase in the amount of protein and oil produced per seed.This project will provide excellent opportunities for undergraduates, graduate students, and postdoctoral fellows to gain significant research experiences, and most importantly, to develop their ability to critically analyze and solve scientific problems. Seed size is a yield trait that traditional plant breeding has limited success in improving. Seed development in major seed crops such as soybean and canola follows a very similar path to Arabidopsis. Enhancing the potential for large seed size represents one of the most promising and least explored avenues for generating a significant increase in agricultural yield.