The Developmental Role of Lateral Organ Boundaries and Related Genes

叶片和其他侧枝器官起源于茎尖分生组织（SAM）的侧翼，形成的侧枝器官根据SAM的位置线索发育出不对称轴。侧器官边界（LOB）基因在SAM和起始侧器官之间的细胞带中表达。LOB的表达既受SAM形成的重要基因调控，也受叶片发育的重要基因调控，这表明LOB可能参与SAM和器官原基之间的信号传导。LOB编码了一种植物特有的新蛋白，并定义了保守的LOB结构域。43个拟南芥基因编码含有LOB结构域的蛋白质。其中，不对称叶片2 （ASYMMETRIC LEAVES2, AS2）、LBD10、LBD25和LBD36与LOB关系最为密切。在目前分析的lob结构域基因中，只有AS2在突变时产生可见的表型。这些观察结果表明，lob结构域基因家族的成员表现出功能冗余。AS2的异位表达导致具有异常的轴向-近轴极性的侧器官的形成，暗示AS2以及可能密切相关的基因参与了近轴细胞命运的建立。本研究的重点是了解LOB及其相关基因在发育中的作用。LOB和密切相关的基因将通过遗传分析来表征。携带单个或多个突变组合的植物将被识别，以揭示每个基因在发育中所起的作用。AS2在极性测定中的作用将被研究。将对LOB顺式调控序列进行表征。将鉴定与LOB相互作用的蛋白质。本研究的长期目标是了解茎尖分生组织形成侧枝器官的机制，特别是lob结构域基因在这一过程中所起的作用。该项目将在一所少数民族高招生院校培养本科生、研究生和一名博士后。

0318822SpringerLeaves and other lateral organs initiate from the flanks of the shoot apical meristem (SAM), and forming lateral organs develop axes of asymmetry in response to positional cues from the SAM. The LATERAL ORGAN BOUNDARIES (LOB) gene is expressed in a band of cells between the SAM and initiating lateral organs. LOB expression is regulated both by genes that are important for SAM formation, and genes that are important for leaf development, suggesting that LOB may be involved in signaling between the SAM and organ primordia. LOB encodes a novel protein that is unique to plants and defines the conserved LOB domain. Forty-three Arabidopsis genes encode proteins that contain a LOB domain. Among these, ASYMMETRIC LEAVES2 (AS2), LBD10, LBD25, and LBD36 are most closely related to LOB. Of the LOB-domain genes thus far analyzed, only AS2 results in a visible phenotype when mutated. These observations suggest that the members of the LOB-domain gene family exhibit functional redundancy. Ectopic expression of AS2 results in the formation of lateral organs that have abnormal abaxial-adaxial polarity, implicating AS2, and perhaps closely related genes, in the establishment adaxial cell fates. This research focuses on understanding the developmental role of LOB and related genes. LOB and closely related genes will be characterized by genetic analyses. Plants that carry single or multiple mutant combinations will be identified to uncover the developmental roles each gene plays. The role of AS2 in polarity determination will be investigated. LOB cis-acting regulatory sequences will be characterized. Proteins that interact with LOB will be identified. The long-term goals of this research are to understand the mechanisms of lateral organ formation from the shoot apical meristem, and in particular what role LOB-domain genes play in this process. The project will provide training for undergraduate and graduate students and a postdoctoral associate in a high minority-enrollment institution.