The Role of Knotted1-Like Homeobox Genes in Shoot Development

0131431 HakeKnotted 1是knox（knotted 1-like homeobox）基因家族的创始成员，该家族已在迄今为止调查的所有植物中被鉴定。同源框基因编码调节其他基因活性的转录因子。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初始下调标志着叶的起始位点。knox基因在叶片中的异位表达由于自发突变或过表达导致叶片形态的显著改变，偶尔异位分生组织和激素水平的变化。功能丧失的knox突变体已经开始揭示不同成员的特定作用。玉米knotted 1（kn 1）和拟南芥STM基因是分生组织起始和/或维持所必需的，而水稻osh 15和拟南芥KNAT 1，也称为短梗（bp），是茎组织所必需的。 在拟南芥中还有另外两个I类knox基因，KNAT 2和KNAT 6。将获得这两个基因的插入等位基因。将进行bp的镶嵌分析以确定KNAT 1在不同组织中的作用。遗传分析将有助于理清不同knox基因在拟南芥中的作用。将采取许多方法来鉴定KNOX家族的靶点，包括表达谱分析、序列比较和生物化学。大量潜在靶标的鉴定将提供确定哪些靶基因与不同的KNOX蛋白是共同的或不同的机会。将分析选定数量的靶基因以确定其功能。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.