The Role of Knotted1-Like Homeobox Genes in Shoot Development

0131431 HakeKnotted1是KNOX(结状同源异型盒)基因家族的创始成员，到目前为止，该家族已在所有调查的植物中发现。同源框基因编码转录因子，调节其他基因的活动。I类KNOX基因在分生组织和茎中表达。KNOX基因在分生组织中的最初下调标志着叶片的起始位置。由于自发突变或过度表达，KNOX基因在叶片中的异位表达会导致叶片形态的戏剧性变化，偶尔会发生异位分生组织和激素水平的变化。功能缺失的NNOX突变体已经开始揭示不同成员的特定角色。玉米结瘤1(Kn1)和拟南芥STM基因是分生组织发生和/或维持所必需的，而水稻osh15和拟南芥KNat1，也被称为BREVIPEDICELLUS(BP)，在茎组织中是必需的。在拟南芥中还有另外两个I类NOX基因，KNA2和KNA6。将获得这两个基因的插入等位基因。将对BP进行镶嵌分析，以确定KNA1在不同组织中的作用。遗传分析将有助于区分不同的诺克斯基因在拟南芥中的作用。将采取许多方法来确定诺克斯家族的靶标，包括表达谱分析、序列比较和生物化学。大量潜在靶点的识别将为确定哪些靶基因对于不同的KNOX蛋白是共同的或不同的提供了机会。将对选定数量的目标基因进行分析，以确定它们的功能。长期目标是了解KNOX蛋白在分生组织维持和植物结构中的作用。

0131431HakeKnotted1 is the founding member of the knox (knotted1-like homeobox) gene family that has been identified in all plants surveyed so far. Homeobox genes encode transcription factors that regulate the activities of other genes. Class I knox genes are expressed in the meristem and stem. The initial down-regulation of knox genes in the meristem marks the site of leaf initiation. Ectopic expression of knox genes in leaves due to spontaneous mutations or overexpression results in dramatic alterations in leaf morphology, occasional ectopic meristems and changes in hormone levels. Loss-of-function knox mutants have begun to reveal specific roles for different members. The maize knotted1 (kn1) and Arabidopsis STM genes are required for meristem initiation and/or maintenance, whereas rice osh15 and Arabidopsis KNAT1, also known as brevipedicellus (bp), are required in stem tissues. There are two other class I knox genes in Arabidopsis, KNAT2 and KNAT6. Insertion alleles will be obtained for these two genes. A mosaic analysis of bp will be carried out to determine the role of KNAT1 in different tissues. Genetic analysis will help sort out the roles for different knox genes in Arabidopsis. A number of approaches will be taken to identify targets of the KNOX family that include expression profiling, sequence comparisons and biochemistry. Identification of a large number of potential targets will provide the opportunity to determine which target genes are in common or distinct to different KNOX proteins. A select number of the target genes will be analyzed to determine their function. The long range goal is to understand the role of KNOX proteins in meristem maintenance and plant architecture.