Control of Organ Initiation and Size by the AINTEGUMENTA Gene

为了了解与器官起始和器官大小决定相关的细胞增殖调节机制，人们正在研究AINTEGUMENTA （ANT）转录因子的功能。ANT是细胞增殖的重要调节因子，负责器官原基的起始和成熟器官大小和形状的决定。1) ANT在产生所有空中侧翼器官原基的分生组织细胞中转录，在产生器官宽度的边缘分生组织细胞中转录，在产生维管系统的分生组织原形成层细胞中转录。2)功能缺失型突变体（无胚珠被、花器官大小和数量减少、叶片狭窄）与细胞增殖能力下降有关。3)在从强35S启动子转录ANT的转基因植物中，功能获得表型（即叶片、花器官和胚珠增大）与细胞增殖增加有关。因此，ANT为信号转导途径提供了一个独特的切入点，该信号转导途径将细胞增殖的控制与器官起始和器官大小和形状的决定联系起来。为了了解器官发生过程中细胞增殖是如何被调节的，PI将完成以下目标：1)确定器官发生过程中ANT转录模式与细胞增殖之间的关系。2)鉴定分生组织细胞中控制ANT转录的基因和序列。3)确定ANT转录因子的靶点，确定其与细胞增殖和器官发生控制的关系。4)阐明蚂蚁相互作用蛋白在细胞增殖和器官发生控制中的作用。5)通过识别抑制或增强弱突变等位基因（ant-3）表型的突变，获得器官发生的其他调节因子。这些实验的结果将为控制器官起始和决定器官大小和形状的基本机制提供见解。它们将有助于阐明器官发生过程中控制细胞增殖的信号转导途径。这些信息将产生新的方法来改变作物的器官大小，从而提高它们的生产力和价值。

To understand mechanisms that regulate cell proliferation associated with organ initiation and the determination of organ size, the function of the AINTEGUMENTA (ANT) transcription factor is being studied. ANT is an important regulator of cell proliferation that is responsible for organ primordia initiation and the determination of mature organ size and shape. 1) ANT is transcribed in meristematic cells that initiate all aerial lateral organ primordia, in marginal meristem cells that contribute to organ width and in meristematic procambium cells that generate the vascular system. 2) The loss-of-function ant mutant phenotype (i.e., no ovule integuments, reduction in floral organ size and number, narrow leaves) is associated with a decrease in cell proliferation. 3) In transgenic plants where ANT is transcribed from the strong 35S promoter, the gain-of-function phenotype (i.e., enlarged leaves, floral organs and ovules) is associated with increased cell proliferation. Thus, ANT provides a unique entry point into the signal transduction pathway(s) that link the control of cell proliferation with organ initiation and the determination of organ size and shape.To understand how cell proliferation is regulated during organogenesis, the PI will accomplish the following goals: 1) Determine the relationship between patterns of ANT transcription and cell proliferation during organogenesis. 2) Identify genes and sequences that control ANT transcription in meristematic cells. 3) Identify targets of the ANT transcription factor and determine their relationship to the control of cell proliferation and organogenesis. 4) Elucidate the role of an ANT interacting protein on the control of cell proliferation and organogenesis. 5) Obtain additional regulators of organogenesis by identifying mutationsthat suppress or enhance the phenotype of a weak mutant allele, ant-3. Results from these experiments will provide insight into fundamental mechanisms that control organ initiation and the determination of organ size and shape. They will help to elucidate the signal transduction pathways that control cell proliferation during organogenesis. This information will generate novel methods to modify organ size in crop plants, and thereby increase their productivity and value.