洋葱AcGAI的克隆及其在开花途径的功能分析

Molecular Cloning and Functional Analysis of AcGAI in Onion Flowering Regulation

以长日照型洋葱品系SB2为材料,克隆获得DELLA家族基因AcGAI。序列分析显示AcGAI编码区全长1575 bp,推测编码524个氨基酸,序列比对表明AcGAI具有典型的DELLA结构域和GRAS结构域。qRT-PCR结果显示AcGAI在洋葱生殖生长期叶片、叶鞘、鳞茎、花茎和花中均有表达,且在花中表达量较高。过表达AcGAI拟南芥转基因株系呈现开花时间延迟;AcGAI在拟南芥gai及della突变体中异源过表达,不同程度地抑制了其早花表型。利用qRT-PCR检测AcGAI过表达植株中光周期核心基因CO和开花调控关键基因FT的表达,发现CO、FT表达量均显著下降。酵母双杂交和双分子荧光互补试验表明AcGAI和AcCO存在互作,说明AcGAI通过调控CO的表达进而延迟植物开花。

AcGAI of DELLA family was cloned from a long-day ecotype onion inbred line SB2.Sequence analysis showed that the full length of AcGAI coding region was 1575 bp,which was estimated to encode 524 amino acids.AcGAI has typical DELLA and GRAS domain.qRT-PCR results showed that AcGAI was expressed in the leaves,leaf sheaths,bulbs,flower stems and flowers of onion during the reproductive growth stage,and the expression level was higher in the flowers.AcGAI overexpressed Arabidopsis thaliana transgenic lines showed delayed flowering time.AcGAI was heterogeneously overexpressed in the gai and della mutants of Arabidopsis thaliana,and the early flowering phenotypes of the gai and della mutants were inhibited to varying degrees.qRT-PCR was used to detect the expressions of the photoperiodic core gene CO and the flowering regulation key gene FT in AcGAI overexpressed plants,and it was found that the expressions of CO and FT were significantly decreased.AcGAI interact with AcCO by yeast two-hybrid system and bimolecular fluorescence complementation technique.This study suggests that GAI involved in flowering regulation by regulating the expression of CO.