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本研究通过RACE-PCR从蓝莓中克隆得到一个R2R3-MYB转录因子,命名为Vc MYB21,该基因全长1 373 bp,编码区722 bp,编码233个氨基酸。生物信息学分析发现其理论分子量为58.37 k Da,p I值为5.12,中部有1个2Fe-2S结合域和1个EGF-like结构域,属于膜外蛋白,结构不稳定。酵母双杂交实验表明Vc MYB21蛋白无自激活活性,能自身形成同源二聚体。组织特异性表达实验显示Vc MYB21主要在蓝莓的果皮和叶片中表达。在蓝莓果实发育过程中,Vc MYB21基因的表达量整体呈下降趋势,在果实发育早期表达量最高,之后迅速下降,全红果时期略微上升;花青素的含量随果实发育持续上升,在紫果期达到最大。UV-B与UV-C处理均显著诱导Vc MYB21在蓝莓幼苗叶片组织中的表达,其中对UV-B处理更为敏感。UV-B处理5 min以及UV-C处理10 min均能显著诱导该基因的表达,随处理时间的延长,基因表达量下降;花青素的含量在基因表达量下降后迅速上升,之后花青素分解,积累量下降。这些研究结果表明Vc MYB21在UV处理后叶片花青素积累过程及蓝莓果实着色过程中可能发挥着负调控作用。
In this study, a R2R3-MYB transcription factor was cloned from blueberry by RACE-PCR and named Vc MYB21. The full-length cDNA was 1 373 bp in length and 722 bp in length encoding 233 amino acids. Bioinformatics analysis showed that the theoretical molecular weight was 58.37 kDa, the p I value was 5.12, and there was one 2Fe-2S binding domain and one EGF-like domain in the middle, belonging to the extramembranous protein with unstable structure. Yeast two-hybrid experiments showed that the Vc MYB21 protein has no self-activating activity and can form homodimers by itself. Tissue-specific expression experiments showed that Vc MYB21 is mainly expressed in the pericarp and leaf of blueberry. During the development of blueberry fruit, the expression level of MYB21 gene in Vc decreased as a whole, and reached its peak at the early stage of fruit development, then decreased rapidly and rose slightly during the period of whole red fruit; the content of anthocyanin continued to increase with the fruit development, The period reaches the maximum. UV-B and UV-C treatment significantly induced the expression of Vc MYB21 in the leaves of blueberry seedlings, which was more sensitive to UV-B treatment. The gene expression was significantly induced by UV-B for 5 min and UV-C for 10 min. The gene expression decreased with the prolongation of treatment time. The content of anthocyanin increased rapidly after the gene expression decreased, Element decomposition, the accumulation of decline. These results indicate that Vc MYB21 may play a negative regulatory role in the process of leaf anthocyanin accumulation and blueberry fruit coloration after UV treatment.