Transcription Factors Regulating Compound Leaf Development in Tomato

在高等植物中，叶的上部(正面)在解剖学和生理学上与叶片底部(背面)不同。这种不对称性(ab-adaxiality)是在叶原基早期建立的，而地上部顶端分生组织(SAM)似乎为这种不对称性的最初建立提供了位置线索。KNOX1基因在维持SAM和随后的新梢发育的不确定性方面发挥着重要作用，而几个物种中的几个基因，如Phan、PHAV、PHAB、REV，被认为指定了侧器官的近轴域和远轴域。据报道，Phan是Knox基因的负调控因子，在形成单叶的顶端，Phan和Knox基因的表达结构域不重叠。然而，在番茄中，KNOX1基因TKN1、LeT6和Phan的表达位于SAM的中心。本研究旨在利用正向遗传学和反向遗传学研究模式生物番茄复叶发育的分子基础，并探讨番茄复叶发育规律是否适用于各种独立进化起源的复叶。初步数据表明，KNOX1基因是导致多种物种复叶形成的发育级联的重要组成部分。此外，Phan表达的结构域和数量调节小叶在不同复叶中的位置。这项拟议的研究将结合使用多种方法，包括分析KNOX1相互作用基因的发育突变，以及同源KNOX1基因和来自简单和复合叶物种的Phan的启动子比较。此外，转基因方法将交换启动子：报告基因在单叶和复合叶物种之间的融合，以及下调和上调KNOX1相互作用蛋白和调控叶片逆行性的蛋白的表达将被用来彻底剖析番茄的复叶发育。这项研究的长期目标是最终将在番茄中学到的原理应用到了解进化背景下的叶片发育。这项活动的更广泛影响包括对博士后研究员、研究生和本科生进行研究方法培训。在过去的资助期间，有几名本科生接受了研究培训，并与人合著了论文，许多本科生来自少数族裔群体。这些活动将在本供资期间继续进行。

0316877SinhaGenerally, the upper (adaxial) part of the leaf is anatomically and physiologically different from the bottom (abaxial) part of the leaf in higher plants. This asymmetry (ab-adaxiality) is established early in the leaf primordium and the shoot apical meristem (SAM) seems to provide positional cues for the initial establishment of this asymmetry. The KNOX1 genes play an important role in maintaining indeterminacy in the SAM and in subsequent shoot development while several genes, like PHAN, PHAV, PHAB, REV, in several species are thought to specify the adaxial and abaxial domains of lateral organs. PHAN is reported to be a negative regulator of KNOX genes and the expression domains of PHAN and KNOX genes do not overlap in apices making simple leaves. However, in tomato expression of the KNOX1 genes TKN1 and LeT6 and PHAN is detected in the center of the SAM. This proposal aims to understand the molecular basis of compound leaf development in the model organism Lycopersicon esculentum (tomato) using both forward and reverse genetics and then to see if the developmental principles discovered in tomato are applicable to various types of compound leaves of independent evolutionary origins. Preliminary data suggests that the KNOX1 genes are an important part of the developmental cascade leading to compound leaves in a variety of species. Further, the domain and amount of PHAN expression regulates leaflet placement in diverse compound leaves. The proposed research will utilize a combination of methods involving analysis of developmental mutations in KNOX1 interacting genes and promoters comparisons for orthologous KNOX1 genes and PHAN from simple and compound leafed species. In addition transgenic approaches will exchange promoter:reporter gene fusions between simple and compound leafed species, and downregulate and upregulate expression of the KNOX1 interacting proteins and proteins that regulate ab-adaxiality in leaves will used to thoroughly dissect compound leaf development in tomato. The long-term goal of this research is to eventually apply the principles learnt in tomato to understanding leaf development in an evolutionary context. Broader impacts of this activity included the training of post-doctoral fellows, graduate students and undergraduates in research methodology. Several undergraduate students have been trained in research and have co-authored papers in the past funding period and many of the undergraduate students come from minority groups. These activities will be maintained in the current funding period.