Genetic and Molecular Analysis of the Knotted (Knl) Gene in Maize

利用转座子标记克隆了影响叶片发育的显性突变位点Knotted （Kn1）。随后的序列分析表明，Kn1编码一个同源结构域，这是一个由许多果蝇发育基因编码的dna结合基序。虽然显性的功能获得突变专门影响叶片，但初步结果表明，在正常植物中，这种蛋白质在分生组织中丰富，在发育中的叶片中检测不到。目前的目标是利用遗传和分子方法了解Kn1基因的野生型功能。将在玉米中分离功能缺失突变，并在转基因植物中异位表达该基因，以评估该基因的表型和功能域。利用玉米基因或推测的拟南芥Kn1同源物，将从拟南芥中分离出非连锁抑制子。体内与Kn1蛋白结合的序列将使用单克隆抗体进行免疫沉淀，以确定哪些基因可能受Kn1调节。Kn1具有许多关键调控基因的特征，包括同源盒、分生组织表达和诱导突变表型。了解Kn1的功能可以为植物发育的遗传控制提供基本的见解。

The Knotted (Kn1) locus, defined by dominant mutations that affect leaf development, was cloned by transposon tagging. Subsequent sequence analysis demonstrated that Kn1 encodes a homeodomain, a DNA-binding motif encoded by a number of Drosophila developmental genes. While the dominant, gain-of-function mutations specifically affect the leaf, initial results demonstrate that in normal plants, the protein is abundant in meristems and not detectable in developing leaves. The present goal is to understand the wildtype function of the Kn1 gene using both genetic and molecular approaches. Loss of function mutations will be isolated in maize and the gene will be ectopically expressed in transgenic plants to evaluate the phenotype and functional domains of the gene. Unlinked suppressors will be isolated in Arabidopsis using either the maize gene or a putative Arabidopsis Kn1 homolog. Sequences bound by the Kn1 protein in vivo will be immunoprecipitated using a monoclonal antibody to determine what genes might be regulated by Kn1. Kn1 has many features expected of a key regulatory gene including the homeobox, meristematic expression, and provocative mutant phenotypes. Understanding how Kn1 functions may provide fundamental insight into the genetic control of plant development.