The leaf is the main organ for rapeseed photosynthesis,and its morphology influences photosynthetic efficiency and supports increased planting density and yield.However,the molecular regulatory mechanism of leaf morph...The leaf is the main organ for rapeseed photosynthesis,and its morphology influences photosynthetic efficiency and supports increased planting density and yield.However,the molecular regulatory mechanism of leaf morphology in Brassica napus is poorly understood,restricting progress in breeding for the trait.We describe a novel dominant mutation,curly leaf 1(cl1),which confers uneven dorsal–ventral axis development,irregular cellular structure and influenced gravitropic response in the seedling stage.The CL1 locus was mapped to a 1.573-Mb interval on chromosome A05 using simple sequence repeat(SSR)markers,and co-segregated with the phenotype of plants in the curly F2 population.A substitution(P62S)was identified in the highly conserved degron motif(GWSPV)of the IAA2 protein in the cl1mutant,and the P62S substitution impaired the interaction between IAA2 and TIR1 in the presence of auxin,influencing auxin signaling.The P62S substitution-induced curly leaf phenotype was verified by ectopic expression of Bna A05.iaa2 in Arabidopsis and B.napus.Our findings explain the function of IAA2 in rapeseed,providing a foundation for future investigation of auxin signaling and the mechanisms underlying leaf development in B.napus.展开更多
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 sho...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.展开更多
基金supported by the National Natural Science Foundation of China(31971902,32001509)China Agriculture Research System of MOF and MARA。
文摘The leaf is the main organ for rapeseed photosynthesis,and its morphology influences photosynthetic efficiency and supports increased planting density and yield.However,the molecular regulatory mechanism of leaf morphology in Brassica napus is poorly understood,restricting progress in breeding for the trait.We describe a novel dominant mutation,curly leaf 1(cl1),which confers uneven dorsal–ventral axis development,irregular cellular structure and influenced gravitropic response in the seedling stage.The CL1 locus was mapped to a 1.573-Mb interval on chromosome A05 using simple sequence repeat(SSR)markers,and co-segregated with the phenotype of plants in the curly F2 population.A substitution(P62S)was identified in the highly conserved degron motif(GWSPV)of the IAA2 protein in the cl1mutant,and the P62S substitution impaired the interaction between IAA2 and TIR1 in the presence of auxin,influencing auxin signaling.The P62S substitution-induced curly leaf phenotype was verified by ectopic expression of Bna A05.iaa2 in Arabidopsis and B.napus.Our findings explain the function of IAA2 in rapeseed,providing a foundation for future investigation of auxin signaling and the mechanisms underlying leaf development in B.napus.
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)+2 种基金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)
文摘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.
