Magidin Mónica, Pittman Jon K, Hirschi Kendal D, Bartel Bonnie
Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005, USA.
Plant J. 2003 Aug;35(4):523-34. doi: 10.1046/j.1365-313x.2003.01826.x.
Plants can regulate levels of the auxin indole-3-acetic acid (IAA) by conjugation to amino acids or sugars, and subsequent hydrolysis of these conjugates to release active IAA. These less active auxin conjugates constitute the majority of IAA in plants. We isolated the Arabidopsis ilr2-1 mutant as a recessive IAA-leucine resistant mutant that retains wild-type sensitivity to free IAA. ilr2-1 is also defective in lateral root formation and primary root elongation. In addition, ilr2-1 is resistant to manganese- and cobalt-mediated inhibition of root elongation, and microsomal preparations from the ilr2-1 mutant exhibit enhanced ATP-dependent manganese transport. We used a map-based positional approach to clone the ILR2 gene, which encodes a novel protein with no predicted membrane-spanning domains that is polymorphic among Arabidopsis accessions. Our results demonstrate that ILR2 modulates a metal transporter, providing a novel link between auxin conjugate metabolism and metal homeostasis.
植物可以通过与氨基酸或糖类结合，以及随后这些共轭物的水解以释放活性吲哚 - 3 - 乙酸（IAA），来调节生长素吲哚 - 3 - 乙酸（IAA）的水平。这些活性较低的生长素共轭物构成了植物中IAA的大部分。我们分离出拟南芥ilr2 - 1突变体，它是一种隐性的IAA - 亮氨酸抗性突变体，对游离IAA保持野生型敏感性。ilr2 - 1在侧根形成和主根伸长方面也存在缺陷。此外，ilr2 - 1对锰和钴介导的根伸长抑制具有抗性，并且来自ilr2 - 1突变体的微粒体制剂表现出增强的ATP依赖性锰转运。我们使用基于图谱的定位方法克隆了ILR2基因，该基因编码一种没有预测跨膜结构域的新型蛋白质，在拟南芥不同生态型之间具有多态性。我们的结果表明，ILR2调节一种金属转运蛋白，在生长素共轭物代谢和金属稳态之间提供了一种新的联系。
