Functional Analyses of Initiation and Laminar Expansion of Plant Lateral Organs

植物由一系列重复的侧面器官组成，这些器官由称为茎分生组织的小块形态形成组织发育而成。叶片为基态侧生器官；在花序和花的发育过程中，产生叶片的发育机制是重复和修改的。因此，对叶片发育的理解是我们理解整个植物发育的核心。以往对不同植物物种的分子遗传分析已经建立了叶片形成和生长机制的可测试模型。此外，比较方法对于更好地理解不同叶片形态是如何进化的很重要，并可能在未来用于农艺优势。本研究将利用影响叶片起始和/或扩张的隐性突变。实验将研究这些基因的表达模式和功能，有助于进一步阐明叶片的发育和形态进化。提出了三个具体目标。(1)玉米/拟南芥基因窄鞘（NARROW SHEATH， NS）/压花（PRESSED FLOWER， PRS）是茎部分生组织形成侧叶域所必需的基因。玉米和拟南芥的叶子是简单的，而番茄的叶子是由许多小叶组成的复叶。将从番茄中克隆出NS/PRS基因，并通过分子遗传学分析确定该基因在番茄复合叶片发育过程中的功能。(2)利用荧光标记蛋白和特异性抗体分析PRS积累和功能的发育时间和分生组织层特异性。这些实验将研究PRS的非细胞自主性机制，其中PRS的功能超出了表达PRS的细胞和组织。(3) RAGGEDSEEDLING2基因将被鉴定，RGD2在玉米发育过程中的表达分析将建立RGD2在叶片横向生长和扩张过程中的功能模型。这些研究活动将与向格鲁吉亚中学生介绍植物生物学研究的努力同时进行。

Plants are comprised of a series of repeated lateral organ segments that develop from small clumps of morphogenic tissue called shoot meristems. The leaf is a ground state lateral organ; the developmental mechanisms generating leaves are repeated and modified during development of inflorescences and flowers. Thus, an understanding of leaf development is central to our comprehension of overall plant development. Previous molecular genetic analyses in diverse plant species have generated testable models for mechanisms of leaf initiation and growth. In addition, comparative approaches are important for better understanding how diverse leaf morphologies have evolved, and may be utilized for agronomic advantage in the future. This research will exploit recessive mutations that affect the initiation and/or expansion of leaves. Experiments will investigate the expression patterns and functions of these genes, helping to elucidate more about the development and morphological evolution of leaves. Three specific aims are proposed. (1) The maize/Arabidopsis genes NARROW SHEATH (NS)/PRESSED FLOWER (PRS) are required for the initiation of lateral leaf domains from shoot meristems. Maize and Arabidopsis leaves are simple, whereas tomato forms compound leaves comprised of many leaflets. The NS/PRS gene will be cloned from tomato, and molecular-genetic analyses will determine the function of this gene during the development of compound tomato leaves. (2) The developmental timing and meristematic tissue layer-specificity of PRS accumulation and function will be analyzed with fluorescently tagged proteins and specific antibodies. These experiments will investigate mechanisms of PRS non-cell autonomy, wherein PRS functions beyond those cells and tissues in which PRS is expressed. (3) The RAGGEDSEEDLING2 gene will be identified and analyses of RGD2 expression during maize development will generate models for how RGD2 functions during the lateral growth and expansion of leaves.These research activities will be performed in parallel with efforts to introduce middle school aged students in Georgia to plant biological research.