AtLAZY1 is a signaling component required for gravitropism of the Arabidopsis thaliana inflorescence. (18th February 2013)

• Record Type: Journal Article
• Authors: Yoshihara, Takeshi; Spalding, Edgar P.; Iino, Moritoshi
• Is Part Of: Plant journal. Volume 74:Number 2(2013:Apr.)
• Page Start: 267
• Page End: 279
• Publication Date: 2013-02-18
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12118
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12118-abs-0001"> <title>Summary</title> <p>The present study identified a family of six <italic>A. thaliana</italic> genes that share five limited regions of sequence similarity with <italic>LAZY1</italic>, a gene in <italic>Oryza sativa</italic> (rice) shown to participate in the early gravity signaling for shoot gravitropism. A T‐DNA insertion into the Arabidopsis gene (<italic>At5g14090</italic>) most similar to <italic>LAZY1</italic> increased the inflorescence branch angle to 81° from the wild type value of 42°. RNA interference lines and molecular rescue experiments confirmed the linkage between the branch‐angle phenotype and the gene consequently named <italic>At</italic><italic>LAZY1</italic>. Time‐resolved gravitropism measurements of <italic>atlazy1</italic> hypocotyls and primary inflorescence stems showed a significantly reduced bending rate during the first hour of response. The subcellular localization of AtLAZY1 protein was investigated to determine if the nuclear localization predicted from the gene sequence was observable and important to its function in shoot gravity responses. AtLAZY1 fused to green fluorescent protein largely rescued the branch‐angle phenotype of <italic>atlazy1</italic>, and was observed by confocal microscopy at the cell periphery and within the nucleus. Mutation of the nuclear localization signal prevented detectable levels of AtLAZY1 in the nucleus without affecting the ability of the gene to rescue the <italic>atlazy1</italic> branch‐angle phenotype. These results indicate that AtLAZY1 functions in gravity signaling during shoot gravitropism, being a functional ortholog of rice LAZY1. The nuclear pool of the protein appears to be unnecessary for this function, which instead relies on a pool that appears to reside at the cell periphery.</p> </abstract>