Genetic and Molecular Analysis of the Dominant Mutations that Define the Kn1 Locus in Zea Mays

玉米的打结突变通过改变某些叶片细胞的分化时间和生长模式来破坏正常的叶片发育。表型范围从通常环绕在侧叶脉周围的光合细胞的清除，到沿着叶平面外生长的侧叶脉的零星结。最后，舌瓣移位并与叶片中的叶脉平行。有四种Kn1突变，它们的严重程度和时间不同，尽管它们都位于1号染色体长臂上的相同位置。我们使用Ds2作为转座子标签克隆了其中一个突变。这种特殊的突变需要一个反式作用的Ac来表达，并且随着Ac剂量的增加，表型的严重程度增加。Ds2突变，Kn1- 2f11，使我们能够开始对另一个Kn1突变，Kn1-0进行分子分析。Kn1-0似乎是一个重复，其断点落在Kn1-2F11中Ds2插入位点的1kb以内。在这两个突变体中改变的远端5kb的DNA是高度保守的。我们将分离和分析不同打结突变及其野生型等位基因的cDNA和基因组克隆。原位杂交技术将用于确定何时以及在什么组织中表达Kn1和野生型基因。将确定Kn1-2F11突变中Ds-Ac相互作用的性质。我们的长期目标是确定叶片的发育如何涉及Kn1或“kn”的表达。重组技术的应用使得在分子遗传水平上研究植物发育成为可能。然而，到目前为止，只有少数实验室开始这样做。由于对玉米进行了广泛的基因研究，它是一种极好的实验生物。这项研究的结果应该能让我们更深入地了解植物是如何形成叶子的。

The knotted mutation in maize disrupts normal leaf development by altering the timing of differentiation and growth pattern of certain leaf cells. The phenotype ranges from a clearing of the photosynthetic cells that normally surround the lateral veins, to sporadic knots along the lateral veins which grow out of the plane of the leaf. Lastly, the ligule is displaced and found parallel to the veins in the leaf blade. There are four Kn1 mutations that differ in their severity and timing although they all map to the same location on the long arm of chromosome 1. We have cloned one of the mutations using Ds2 as a transposon tag. This particular mutation requires a trans-acting Ac for expression and the phenotype increases in severity with an increase in Ac dosage. The Ds2 mutation, Kn1-2F11, has enabled us to begin a molecular analysis of another Kn1 mutation, Kn1-0. Kn1-0 appears to be a duplication, the breakpoint of which falls within 1 kb of the site of the Ds2 insertion in Kn1-2F11. DNA 5 kb distal to the region altered in these two mutants is highly conserved. We will isolate and analyze cDNA and genomic clones of the different knotted mutations and their wildtype alleles. In situ hybridization techniques will be used to determine when and in what tissues the Kn1 and wildtype genes are expressed. The nature of the Ds-Ac interaction in the Kn1-2F11 mutation will be determined. Our long range goal is to determine how the development of the leaf involves Kn1 or "kn" expression. The use of recombinant technology has made it possible to study plant development at a molecular genetic level. However, as yet, only a few laboratories have started doing so. Corn, because it has been genetically studied extensively, is an excellent experimental organism. The results of this study should provide greater insight into how plants form leaves.