College of Horticulture, Northwest A&F University, Taicheng Road NO.3, Yangling 712100, Shaanxi Province, China.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Taicheng Road NO.3, Yangling 712100, Shaanxi Province, China.
Int J Mol Sci. 2020 Feb 24;21(4):1528. doi: 10.3390/ijms21041528.
Subgroup 4 R2R3 MYBs play vital roles in the regulation of anthocyanin biosynthesis. However, there is limited knowledge regarding the functions of MYB repressors in pear (). Here, PbMYB120 was identified as a potential regulator of anthocyanin biosynthesis. A phylogenetic analysis revealed that PbMYB120 was clustered into the FaMYB1-like clade of the subgroup 4 R2R3 MYBs. was expressed higher in red peels than in green peels in five pear cultivars. expression was positively correlated with anthocyanin accumulation. However, the transient overexpression of led to the inhibition of anthocyanin accumulation and expression. Promoter binding and activation assays indicated that PbMYB120 binds to the promoter of and represses the promoter's activity. Thus, the inhibition of anthocyanin accumulation by PbMYB120 may be correlated with the repression of . Furthermore, during anthocyanin induction, the expression levels of anthocyanin activators and were upregulated. This study demonstrated that was highly expressed in pear tissues having higher anthocyanin accumulations but acted as a repressor in the regulation of anthocyanin accumulation. PbMYB120 may work coordinately with anthocyanin activators and serve as a balancer of anthocyanin accumulation.
第四亚组 R2R3 MYB 蛋白在调控花色苷生物合成中发挥着重要作用。然而，关于梨中 MYB 抑制子的功能知之甚少（）。在这里，PbMYB120 被鉴定为花色苷生物合成的一个潜在调控因子。系统发育分析表明，PbMYB120 聚类到第四亚组 R2R3 MYB 的 FaMYB1 亚类中。在五个梨品种中，PbMYB120 在红色果皮中的表达高于绿色果皮。表达与花色苷积累呈正相关。然而，瞬时过表达 导致花色苷积累和 表达受到抑制。启动子结合和激活分析表明，PbMYB120 结合到 启动子上并抑制启动子的活性。因此，PbMYB120 对花色苷积累的抑制可能与对 的抑制有关。此外，在花色苷诱导过程中，花色苷激活子和 的表达水平上调。本研究表明，在花色苷积累较高的梨组织中高度表达，但在花色苷积累的调控中作为一个抑制子发挥作用。PbMYB120 可能与花色苷激活子协同作用，作为花色苷积累的平衡因子。
