College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou, China.
Key Laboratory of Post-Harvest Handling of Fruits, Ministry of Agriculture and Rural Affairs; Key Laboratory of Fruits and Vegetables Postharvest and Processing Technology Research of Zhejiang Province; Key Laboratory of China Light Industry, Food Science Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
J Sci Food Agric. 2020 Sep;100(12):4442-4448. doi: 10.1002/jsfa.10484. Epub 2020 May 26.
MYB transcription factors (TFs) are common in plants and play important functions in growth and development, including fruit development and ripening. However, the role of MYB proteins in papaya ripening (fruit ripening and carotenoid biosynthesis) remains unclear.
Two MYB genes were cloned from papaya pulp. They were named CpMYB1 (MYB44-like) and CpMYB2, and belong to the S22 subgroup of the R2R3-MYB family. Their expression levels decreased during fruit ripening. Subcellular localization analysis showed that both CpMYB1 and CpMYB2 were nuclear proteins, indicating that they might function in the nucleus. Moreover, CpMYB1 and CpMYB2 could bind to the promoters of cell-wall degradation genes (CpPME1, CpPME2, and CpPG5) and carotenoid biosynthesis genes (CpPDS2, CpPDS4, and CpCHY-b). Further research found that both CpMYB1 and CpMYB2 were transcriptional repressors, and they could suppress the activities of the promoters of CpPME1, CpPME2, CpPG5, CpPDS2, CpPDS4, and CpCHY-b.
These results indicated that MYB TFs CpMYB1 and CpMYB2 might have a function in papaya fruit softening and carotenoid accumulation by regulating cell-wall degradation and carotenoid biosynthesis related genes, which provide a new view about the role of MYB TFs in fruit ripening. © 2020 Society of Chemical Industry.
MYB 转录因子（TFs）在植物中很常见，在生长和发育中发挥着重要作用，包括果实发育和成熟。然而，MYB 蛋白在木瓜成熟（果实成熟和类胡萝卜素生物合成）中的作用尚不清楚。
从木瓜果肉中克隆了两个 MYB 基因。它们被命名为 CpMYB1（MYB44 样）和 CpMYB2，属于 R2R3-MYB 家族的 S22 亚群。它们的表达水平在果实成熟过程中下降。亚细胞定位分析表明，CpMYB1 和 CpMYB2 均为核蛋白，表明它们可能在核内发挥作用。此外，CpMYB1 和 CpMYB2 可以与细胞壁降解基因（CpPME1、CpPME2 和 CpPG5）和类胡萝卜素生物合成基因（CpPDS2、CpPDS4 和 CpCHY-b）的启动子结合。进一步的研究发现，CpMYB1 和 CpMYB2 均为转录抑制因子，它们可以抑制 CpPME1、CpPME2、CpPG5、CpPDS2、CpPDS4 和 CpCHY-b 启动子的活性。
这些结果表明，MYB TFs CpMYB1 和 CpMYB2 可能通过调节细胞壁降解和类胡萝卜素生物合成相关基因在木瓜果实软化和类胡萝卜素积累中发挥作用，为 MYB TFs 在果实成熟中的作用提供了新的视角。© 2020 英国化学学会。
