拟南芥MeIAA抗性突变体的筛选和初步图位克隆分析

生长素是最重要的植物激素之一，参与了植物生长发育的各个方面。植物体内游离的IAA是生长素的主要活性形式，在IAA甲基转移酶1（IAMT1）的作用下，IAA可以转变为IAA甲酯（MelAA）。MelAA本身没有活性，在植物体内的MelAA酯解酶作用下可以重新转变为IAA。MelAA是非极性分子，能够在植物体内自由扩散。利用MelAA的这种特殊性质筛选突变体，可以分离到MelAA代谢途径或者IAA途径中新的成分。我们对拟南芥种子进行EMS诱变，通过观察黑暗下下胚轴的生长情况，筛选MelAA的抗性突变体。我们成功分离到了8株可能的抗性突变体，并对其中的一个Methyl-JAAresistant1（mir1）突变体进行了深入分析。MelAA抗性突变体的筛选将为进一步了解MelAA的代谢、IAA稳态调控和响应机理提供新的材料。

Isolation and Positional Cloning of Methyl-lndole-3-Acetic Acid Resistant Mutants in Arabidopsis

Auxin is one of the most important plant hormones in that it regulates almost all aspects of plant growth and development. In plants, free indole-3-acetic acid （IAA） is the major active auxin and can be converted to methyl-lAA （MelAA） with the activity of an IAA carboxyl methyltransferase 1 （IAMT1）. However, MelAA is also an inactive form of IAA and can be converted to IAA catalyzed by several esterases. MelAA is a non-polar IAA form and can diffuse between cells, so MelAA is suitable for screening new components in MelAA metabolism or IAA biology. Here, we screened ethyl-methane-sulphonate （EMS）-mutagensis seedlings on MelAA medium in the dark, with longer hypocotyls used as a criterion. We isolated 8 putative MelAA-resistant mutants and carried out further experiments on one mutant, mir1. These new mutants will help shed light on MelAA metabolism and the action mechanism of IAA.