A Gain-of-Function Mutation in IAA7/AXR2 Confers Late Flowering under Short-day Light in Arabidopsis  

作　　者：Yan-Xia Mai Long Wang Hong-Quan Yang 

机构地区：[1]National Key Laboratory of Plant Molecular Genetics, Institute o1 Plant Physiology and Ecology, Shanghai Institutes tor ~iolog~calSciences, the Chinese Academy of Sciences, Shanghai 200032, China [2]Plant Science Institute, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai 200240, China

出　　处：《Journal of Integrative Plant Biology》2011年第6期480-492,共13页植物学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (90917014 to H.-Q.Y.);the Ministry of Science and Technology of China (2006AA10A102);the National Special Grant for Transgenic Crops (2009ZX08009-081B to H.-Q.Y.);the Science and Technology Commission of Shanghai Municipality(10XD1402300 to H.-Q.Y.);the Shanghai Leading Academic Discipline Project(B209)

摘　　要：Floral initiation is a major step in the life cycle of plants, which is influenced by photoperiod, temperature, and phytohormones, such as gibberellins （GAs）. It is known that GAs promote floral initiation under short-day light conditions （SDs） by regulating the floral meristem-identity gene LEAFY （LFY） and the flowering-time gene SUPPRESSOR OF OVEREXPRESSION OF CO 1 （SOC1）. We have defined the role of the auxin signaling component INDOLE-3-ACETIC ACID 7 （IAA7）/AUXIN RESISTANT 2 （AXR2） in the regulation of flowering time in Arabidopsis thaliana. We demonstrate that the gain-of-function mutant of IAA7/AXR2, axr2-1, flowers late under SDs. The exogenous application of GAs rescued the late flowering phenotype of axr2-1 plants. The expression of the GA20 oxidase （GA2Oox） genes, GA2Ooxl and GA2Oox2, was reduced in axr2-1 plants, and the levels of both LFY and SOC1 transcripts were reduced in axr2-1 mutants under SDs. Furthermore, the overexpression of SOC1 or LFY in axr2-1 mutants rescued the late flowering phenotype under SDs. Our results suggest that IAA7/AXR2 might act to inhibit the timing of floral transition under SDs, at least in part, by negatively regulating the expressions of the GA2Ooxl and GA2Oox2 genes.Floral initiation is a major step in the life cycle of plants, which is influenced by photoperiod, temperature, and phytohormones, such as gibberellins （GAs）. It is known that GAs promote floral initiation under short-day light conditions （SDs） by regulating the floral meristem-identity gene LEAFY （LFY） and the flowering-time gene SUPPRESSOR OF OVEREXPRESSION OF CO 1 （SOC1）. We have defined the role of the auxin signaling component INDOLE-3-ACETIC ACID 7 （IAA7）/AUXIN RESISTANT 2 （AXR2） in the regulation of flowering time in Arabidopsis thaliana. We demonstrate that the gain-of-function mutant of IAA7/AXR2, axr2-1, flowers late under SDs. The exogenous application of GAs rescued the late flowering phenotype of axr2-1 plants. The expression of the GA20 oxidase （GA2Oox） genes, GA2Ooxl and GA2Oox2, was reduced in axr2-1 plants, and the levels of both LFY and SOC1 transcripts were reduced in axr2-1 mutants under SDs. Furthermore, the overexpression of SOC1 or LFY in axr2-1 mutants rescued the late flowering phenotype under SDs. Our results suggest that IAA7/AXR2 might act to inhibit the timing of floral transition under SDs, at least in part, by negatively regulating the expressions of the GA2Ooxl and GA2Oox2 genes.

关 键 词：ARABIDOPSIS GA 20-oxidases GAs IAA7/AXR2 auxin. 

分 类 号：S682.11[农业科学—观赏园艺] S511[农业科学—园艺学]