Brassinosteroids and Auxin Down-Regulate DELLA Genes in Fiber Initiation and Elongation of Cotton

doi:10.1016/S1671-2927(11)60107-7

摘要/Abstract

摘要： Plant hormones play important roles in cotton fiber growth and development. However, the interaction of phytohormonesis largely unknown in fiber cells up to now. DELLA proteins are critical component in GA (gibberellic acid) signaltransduction, which are also regulated by other phytohormones, such as auxin and ethylene. To understand the regulationof DELLA genes in cotton fiber growth and development, we cloned four DELLA genes from upland cotton fibers(Gossypium hirsutum L.), named GhGAI1, GhGAI2, GhGAI3, and GhGAI4. Alignment of the four predicted proteins withother reported DELLA proteins in various species displayed that they shared conserved domains and high homology.Expression profiles of the four GhGAIs in various tissues and organs as well as cotton fibers in different stages displayedthat GhGAI1 has higher transcriptional levels than other GhGAIs in all detected samples. Furthermore, the expressionlevel of GhGAI1 was significantly reduced in 0 dpa (day post anthesis) ovules by addition of IAA and epi-BL, andexogenous epi-BL decreased GhGAI1 level in 7 dpa fiber. Similarly, the levels of the other three GhGAIs in 0 dpa ovulesand 7 dpa fibers were also regulated by applied phytohormones. In addition, the levels of GhGAI1 were higher inXuzhou142 fl mutant (fuzzless-lintless) than in FL (Gossypium hirsutum vs. Xuzhou 142) from -1 to 3 dpa ovules, suggestingthat GhGAI1 engaged in cotton fiber cell initiation. These results indicated that DELLA genes are involved in the processof fiber cell initiation and elongation regulated by different phytohormones.

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关键词: DELLA protein, upland cotton, cotton fiber development, phytohormone

Abstract: Plant hormones play important roles in cotton fiber growth and development. However, the interaction of phytohormonesis largely unknown in fiber cells up to now. DELLA proteins are critical component in GA (gibberellic acid) signaltransduction, which are also regulated by other phytohormones, such as auxin and ethylene. To understand the regulationof DELLA genes in cotton fiber growth and development, we cloned four DELLA genes from upland cotton fibers(Gossypium hirsutum L.), named GhGAI1, GhGAI2, GhGAI3, and GhGAI4. Alignment of the four predicted proteins withother reported DELLA proteins in various species displayed that they shared conserved domains and high homology.Expression profiles of the four GhGAIs in various tissues and organs as well as cotton fibers in different stages displayedthat GhGAI1 has higher transcriptional levels than other GhGAIs in all detected samples. Furthermore, the expressionlevel of GhGAI1 was significantly reduced in 0 dpa (day post anthesis) ovules by addition of IAA and epi-BL, andexogenous epi-BL decreased GhGAI1 level in 7 dpa fiber. Similarly, the levels of the other three GhGAIs in 0 dpa ovulesand 7 dpa fibers were also regulated by applied phytohormones. In addition, the levels of GhGAI1 were higher inXuzhou142 fl mutant (fuzzless-lintless) than in FL (Gossypium hirsutum vs. Xuzhou 142) from -1 to 3 dpa ovules, suggestingthat GhGAI1 engaged in cotton fiber cell initiation. These results indicated that DELLA genes are involved in the processof fiber cell initiation and elongation regulated by different phytohormones.

Key words: DELLA protein, upland cotton, cotton fiber development, phytohormone

HU Ming-yu, LUO Ming, XIAO Yue-hua, LI Xian-bi, TAN Kun-ling, HOU Lei, DONG Jing, LI De-mou, SONG Shui-qing, ZHAO Juan, ZANG Zhen-le, LI Bao-li , PEI Yan. Brassinosteroids and Auxin Down-Regulate DELLA Genes in Fiber Initiation and Elongation of Cotton[J]. Journal of Integrative Agriculture, 2011, 10(8): 1168-1176.

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