The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier
The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier
复制标题
DOI：
10.1073/pnas.95.25.15112
复制
发表时间：
1998-12-08
影响因子：
11.1
通讯作者：
Masson, PH
中科院分区：
文献类型：
--
作者：
Chen, RJ;Hilson, P;Masson, PH
甜菜碱是调节植物生长和发育的许多方面的植物激素。在高等植物中，生长素从茎尖的合成位点极性运输到茎基部区域和根中的作用位点。生长素极性运输是生长素功能的一个重要方面，并由细胞内流和外流载体介导。关于其调节组分，外排载体的分子特性知之甚少[Estelle，M.（1996）Current Biol.6，1589-1591]。在这里，我们表明，在拟南芥AGRAVITROPIC 1（AGR 1）基因的突变参与根向地性赋予根生长的敏感性增加生长素和乙烯和生长素运输抑制剂的敏感性降低，并导致保留外源添加的生长素在根尖细胞中，我们使用位置克隆显示，AGR 1编码一个假定的跨膜蛋白，其氨基酸序列与细菌转运蛋白的同源性。当在酿酒酵母中表达时，AGR 1促进放射性标记的IAA从细胞中流出增加，并赋予对氟IAA（一种毒性IAA衍生化合物）的抗性增加。AGR 1转录本定位于根远端伸长区，一个区域经历了一个弯曲的反应后，重力刺激。我们已经确定了几个AGR 1相关基因在拟南芥中，这表明该基因家族在生长素调控的生长和发育过程中的控制的全球性作用。
Auxins are plant hormones that mediate many aspects of plant growth and development. In higher plants, auxins are polarly transported from sites of synthesis in the shoot apex to their sites of action in the basal regions of shoots and in roots. Polar auxin transport is an important aspect of auxin functions and is mediated by cellular influx and efflux carriers. Little is known about the molecular identity of its regulatory component, the efflux carrier [Estelle, M. (1996) Current Biol. 6, 1589-1591]. Here we show that mutations in the Arabidopsis thaliana AGRAVITROPIC 1 (AGR1) gene involved in root gravitropism confer increased root-growth sensitivity to auxin and decreased sensitivity to ethylene and an auxin transport inhibitor, and cause retention of exogenously added auxin in root tip cells, We used positional cloning to show that AGR1 encodes a putative transmembrane protein whose amino acid sequence shares homologies with bacterial transporters. When expressed in Saccharomyces cerevisiae, AGR1 promotes an increased efflux of radiolabeled IAA from the cells and confers increased resistance to fluoro-IAA, a toxic IAA-derived compound. AGR1 transcripts were localized to the root distal elongation zone, a region undergoing a curvature response upon gravistimulation. We have identified several AGR1-related genes in Arabidopsis, suggesting a global role of this gene family in the control of auxin-regulated growth and developmental processes.