Phloem-Mobile AuxlIAA Transcripts Target to the Root Tip and Modify Root Architecture  

Phloem-Mobile Aux/IAA Transcripts Target to the Root Tip and Modify Root Architecture

作　　者：Michitaka Notaguchi Shmuel Wolf William J.Lucas 

机构地区：[1]Department of Plant Biology,College of Biological Sciences,University of California,Davis,CA 95616,USA [2]JST ERATO Higashiyama Live-Holonics Project,Nagoya University,Furo-cho,Chikusa-ku,Nagoya,auAichi 464-8602,Japan [3]The Robert H.Smith Institute of Plant Sciences and Genetics in Agriculture and the Otto Warburg Minerva Center for Agricultural Biotechnology,The Hebrew University of Jerusalem,The Robert H.Smith Faculty of Agriculture,Food and Environment,Rehovot 76100,Israel

出　　处：《Journal of Integrative Plant Biology》2012年第10期760-772,共13页植物学报（英文版）

基　　金：supported by a grant from the United States-Israel Binational Science Foundation(BSF 2007052,to W.J.L.and S.W.);by a Postdoctoral Fellowship for Research Abroad from the Japanese Society for the Promotion of Science(awarded to Michitaka Notaguchi).

摘　　要：In plants, the phloem is the component of the vascular system that delivers nutrients and transmits signals from mature leaves to developing sink tissues. Recent studies have identified proteins, mRNA, and small RNA within the phloem sap of several plant species. It is now of considerable interest to elucidate the biological functions of these potential long-distance signal agents, to further our understanding of how plants coordinate their developmental programs at the whole-plant level. In this study, we developed a strategy for the functional analysis of phloem-mobile mRNA by focusing on IAA transcripts, whose mobility has previously been reported in melon （Cucumis melo cv. Hale＇s Best Jumbo）. Indoleacetic acid （IAA） proteins are key transcriptional regulators of auxin signaling, and are involved in a broad range of developmental processes including root development. We used a combination of vasculature-enriched sampling and hetero-grafting techniques to identify IAA18 and IAA28 as phloemmobile transcripts in the model plant Arabidopsis thaliana. Micro-grafting experiments were used to confirm that these IAA transcripts, which are generated in vascular tissues of mature leaves, are then transported into the root system where they negatively regulate lateral root formation. Based on these findings, we present a model in which auxin distribution, in combination with phloem-mobile Aux/IAA transcripts, can determine the sites of auxin action.In plants, the phloem is the component of the vascular system that delivers nutrients and transmits signals from mature leaves to developing sink tissues. Recent studies have identified proteins, mRNA, and small RNA within the phloem sap of several plant species. It is now of considerable interest to elucidate the biological functions of these potential long-distance signal agents, to further our understanding of how plants coordinate their developmental programs at the whole-plant level. In this study, we developed a strategy for the functional analysis of phloem-mobile mRNA by focusing on IAA transcripts, whose mobility has previously been reported in melon （Cucumis melo cv. Hale＇s Best Jumbo）. Indoleacetic acid （IAA） proteins are key transcriptional regulators of auxin signaling, and are involved in a broad range of developmental processes including root development. We used a combination of vasculature-enriched sampling and hetero-grafting techniques to identify IAA18 and IAA28 as phloemmobile transcripts in the model plant Arabidopsis thaliana. Micro-grafting experiments were used to confirm that these IAA transcripts, which are generated in vascular tissues of mature leaves, are then transported into the root system where they negatively regulate lateral root formation. Based on these findings, we present a model in which auxin distribution, in combination with phloem-mobile Aux/IAA transcripts, can determine the sites of auxin action.

关 键 词：Arabidopsis AUX/IAA lateral root development GRAFTING phloem-mobile transcript. 

分 类 号：Q943[生物学—植物学]