Epigenetics of Plant Developmental Transitions - Repressors of the Embryonic Program

种子在经济上是植物农业中最重要的最终产品。提高种子质量需要对种子发育有透彻的了解，特别是在种子成熟后期，蛋白质、淀粉、脂质等储存储备正在合成和积累。种子贮藏蛋白（Seed storage protein， SSP）基因一直被认为是研究种子成熟过程的分子标记，也是研究组织特异性基因表达调控的模型系统。一些基因被认为是种子成熟的主要调控因子，包括ssp，但目前关于这些基因的调控及其与靶标的相互作用的知识仍然是碎片化的。我们已经在拟南芥（分子生物学研究的模式植物）中进行了基因筛选，寻找调控ssp表达的基因。在一个筛选中，我们发现了种子成熟基因在叶片中异位表达的突变体。这些突变表型背后的基因的身份已经被揭示：它们大多是通过改变染色质结构来调节基因表达的表观遗传调节剂。本文提出的研究是基于我们之前的工作，并继续寻找和表征控制种子成熟程序表达的遗传和表观遗传网络。这项工作的完成将丰富和拓宽我们对植物种子和营养发育过程中基因表达调控的认识。由于种子成熟程序是一个进化保守的发育程序，从模式植物拟南芥中获得的知识可以很容易地转移到双子叶作物中，如油菜、大豆和普通豆，并最终有助于未来种子质量的提高。

Seeds are economicaly the most important end product in plant agriculture. The improvement of seed quality requires a thorough understanding of seed development, particularly in the later phase of seed maturation, when storage reserves such as proteins, starches, lipids and other nutrients are being synthesized and accumulated. Seed storage protein (SSP) genes have long been considered as molecular markers for the study of seed maturation and as a model system for the investigation of the control of tissue specific gene expression. A few genes are known as master regulators of seed maturation including of SSPs, but present knowledge on these genes' regulation and interaction with their targets is still fragmented. We have already performed a genetic screen in Arabidopsis (a model plant for molecular biology research) to look for genes that regulate the expression of SSPs. In one screen, we identified mutants where seed maturation genes are ectopically expressed in leaves. The identities of these genes underlying the mutant phenotypes have been revealed: they are mostly epigenetic regulators that regulate gene expression by modifying the structure of chromatin. The research proposed here is based on our previous work and continues to search for and characterize the genetic and epigenetic network that controls the expression of the seed maturation program. This work, when completed, will enrich and broaden our knowledge on gene expression regulation during plant seed and vegetative development. Since the seed maturation program is an evolutionarily conserved developmental program, the knowledge gained from the model plant Arabidopsis can easily be transferred to dicotyledonous crops, such as canola, soybean and common bean, and will ultimately contribute to seed quality improvement in the future.