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J EXP BOT：棉花AAI基因家族全基因组鉴定及功能分析

已有 3454 次阅读 2019-5-22 15:18 |个人分类:每日摘要|系统分类:论文交流

Genome-wide identification of GhAAI genes reveals that GhAAI66 triggers a phase transition to induce early flowering

First author: Ghulam Qanmber; Affiliations: Institute of Cotton Research, Chinese Academy of Agricultural Sciences (中国农业科学院棉花研究所): Anyang, China

Corresponding author: Fuguang Li

Plants undergo a phase transition from vegetative to reproductive development that triggers floral induction. Genes containing an AAI (alpha amylase inhibitor) domain form a large gene family, but there have been no comprehensive analyses of this gene family in any plant species. Here, we identified 336 AAI genes from nine plant species including 122 AAI genes in cotton (Gossypium hirsutum). The AAI gene family has evolutionarily conserved amino acid residues throughout the plant kingdom. Phylogenetic analysis classified AAI genes into five major clades with significant polyploidization and showing effects of genome duplication. Our study identified 42 paralogous and 216 orthologous gene pairs resulting from segmental and whole genome duplication, respectively, demonstrating significant contributions of gene duplication in expansion of the cotton AAI gene family. Further, GhAAI66 was preferentially expressed in flower tissue and responses to phytohormone treatments. Ectopic expression in Arabidopsis and silencing of GhAAI66 revealed that GhAAI66 triggers a phase transition to induce early flowering. Further, GO and KEGG analysis of RNA-seq data and qRT-PCR analysis indicated that GhAAI66 integrates multiple flower signaling pathways including GA, JA, and floral integrators to trigger an early flowering cascade in Arabidopsis. Therefore, characterization of AAI family provides invaluable insights for improving cotton breeding.

植物在生长过程中会经历一个从营养生长向生殖生长的发育状态转变，从而诱导植物开花。包含α-淀粉酶抑制因子AAI的基因属于一个大的基因家族，但目前还没有对于该基因家族进行综合分析的报道。本文，作者基于9个植物物种鉴定了336个AAI基因，其中棉花中就有122个AAI基因。植物的AAI基因家族具有十分保守的氨基酸序列。系统发育分析显示AAI基因家族又可以划分为五个亚家族，进化树显示出了明显的多倍化，揭示了基因组复制对于AAI基因扩张的影响。作者的研究鉴定了源自部分基因组复制产生的42个旁系同源基因和源自全基因组复制产生的216个直系同源基因对，说明了基因复制事件对于AAI基因扩张的促进作用。此外，GhAAI66基因优先在花组织中表达，并且响应于植物激素的处理。在拟南芥中异源表达GhAAI66基因和GhAAI66沉默揭示了GhAAI66能够诱导植株发育状态的改变，并诱导植株提前开花。另外，转录组测序的GO和KEGG分析以及qRT-PCR分析显示GhAAI66基因整合了多个开花信号通路，包括GA、JA和开花整合因子来诱导拟南芥中的早花级联。因此，对于AAI家族的研究为棉花育种的改善提供了新的视野。