植物器官发育是一个高度有序的过程，从细胞层面来看，会经历细胞分裂由活跃到终止，继而进入分化阶段的转变。此转变发生的时空特异性极大决定了器官最终的大小与形状。现有的研究已经发现了一系列调控细胞分裂分化的基因，但对这些基因如何协同控制器官生长的时空变化仍然缺乏足够的认识。本项目针对这一问题，在模式植物拟南芥花瓣里深入探究器官生长的时空调节机理。本课题组前期研究了三个在花瓣生长特定阶段和部位起关键作用的转录因子：RBE、JAG 和TCP5。RBE和JAG在细胞分裂活跃的时空区域表达，并促进细胞分裂和花瓣生长；TCP5表达局限在细胞分裂活性低的区域，它恰好是细胞分裂和生长负调控基因。本项目中，我们将利用转录组分析等基因组学方法结合其他遗传、分子及发育生物学手段研究三个基因下游调控网络及相互关系，由此阐明三者如何共同作用调节花瓣生长的时空变化过程，并以此为基础，深入剖析植物器官发育的时空调节机理。

Plant organ development is a highly ordered process. At the cellular level, early stage organs usually consist of cells undergoing active cell divisions. As the organ grows, certain cells will cease division and enter the phase of cell differentiation. This transition often occurs in a temporal and spatial specific fashion that largely determines the final size and shape of the organ. Recent studies have uncovered a number of genes involved in controlling cell division and differentiation during plant organ development, however, our understanding of the gene network regulating the temporal and spatial changes in organ growth is still limited. In this project, we propose to utilize the Arabidopsis petal as a model system to further study the temporal and spatial regulatory mechanisms of plant organ growth. Specifically, we will focus on investigating three key transcription factors that we analyzed previously, RBE, JAG and TCP5, which conduct temporal and spatial-specific roles during petal growth: RBE and JAG are expressed at the stages and regions with active cell divisions, and function to promote cell division and petal growth. In contrast, TCP5 is localized in the cells with low division activities, and acts as a negative regulator of cell division and petal growth. We propose to employ genomic approaches, such as transcriptome analysis, in combination with other genetic, molecular and developmental biology techniques to characterize the interactions of the downstream genetic networks of the three genes. Through these experiments, we aim to elucidate how these three genes function together in the temporal and spatial regulation of petal growth. In the long term, we hope to use these results as a launch pad for further understanding the general mechanisms that establish temporal and spatial patterns of plant organ development.