Abstract: Flowering is an essential stage of flowering plants for determining the success of propagation. In the previous study, a MYB gene in D03 chromosome related to flowering time was found through genome-wide association study in Gossypium hirsutum. In this study, a MYB gene was cloned from Gossypium hirsutum, and two homologous genes were obtained and their amino acid sequences similarity was as high as 95%, which were named as GhMYB44a and GhMYB44b and  located in D03 and A02 chromosomes, respectively. GhMYB44a was 1 322 bp in length and contained 987 bp open reading frame (ORF). GhMYB44b was 1 313 bp in length with a 984 bp ORF. The theoretical isoelectric points of the two proteins were 8.93 and 9.15, respectively, and the sequence differences in the C-terminal caused significant differences in structure. Both GhMYB44a and GhMYB44b contained two MYB repeat domains and located in the nucleus, suggesting their roles as R2R3 type MYB transcription factors. GhMYB44a and GhMYB44b were expressed ubiquitously with the highest transcripts in the cotton leaves. GhMYB44a responded to PEG stress, and GhMYB44b responded to PEG and salt stresses. Overexpression of GhMYB44a and GhMYB44b promoted early-flowering of Arabidopsis, of which, the early flowering phenotype of 35S:GhMYB44a was more obvious.

Key words: cotton, GhMYB44, flowering time, expression level, gene function

摘要： 开花是有花植物重要的发育阶段，决定繁殖的成功与否。从陆地棉基因组中克隆了一个与开花时间相关的MYB基因，得到两条同源序列，氨基酸序列相似度高达95%，位于D03和A02染色体上，分别命名为GhMYB44a和GhMYB44b。GhMYB44a全长1 322 bp，包含987 bp开放阅读框，GhMYB44b全长1 313 bp，包含984 bp开放阅读框，编码的蛋白理论等电点分别为8.93和9.15，C端序列的差异导致两个蛋白的结构明显不同。GhMYB44a和GhMYB44b均包含两个MYB repeat结构域，属于R2R3型MYB转录因子，两个蛋白均定位于细胞核内。转录组数据显示，GhMYB44a在棉花根、茎、叶、雌蕊中表达，而GhMYB44b在茎、叶、雌蕊、花托中表达，且两个基因均在叶片中的表达量最高；GhMYB44a响应PEG胁迫，GhMYB44b响应PEG和盐胁迫。两个基因的表达差异预示着其功能可能也存在不同。超表达GhMYB44a和GhMYB44b都促进拟南芥早开花，但GhMYB44a转基因植株的早花现象更加明显。

关键词: 棉花, GhMYB44, 开花时间, 表达量, 基因功能