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

玉米中的打结突变通过改变某些叶细胞的分化和生长模式来扰乱正常的叶片发育。表型范围从通常围绕侧脉的光合作用细胞的清除，到沿着侧脉的零星结节，这些节沿侧脉生长在叶片平面之外。最后，叶舌被移位并与叶片中的叶脉平行。有四个Kn1突变在严重程度和时间上不同，尽管它们都映射到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反式作用的Ac来表达，而且随着Ac剂量的增加，表型的严重性也会增加。DS2突变Kn1-2F11使我们能够开始对另一种Kn1突变Kn1-0进行分子分析。Kn1-0似乎是一个重复，其断裂点落在Kn1-2F11中DS2插入位置的1kb以内。在这两个突变体中改变的区域远端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。将使用原位杂交技术来确定Kn1和野生型基因何时以及在哪些组织中表达。Kn1-2F11突变中DS-Ac相互作用的性质将被确定。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。重组技术的使用使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，只有几个实验室开始这样做。玉米是一种很好的实验生物，因为它经过了广泛的遗传学研究。这项研究的结果应该会对植物如何形成叶子提供更多的见解。

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.