Temperature changes affect apple development and production. Phenylpropanoid metabolism and hormone signaling play a crucial role in regulating apple growth and development in response to temperature changes. Here, we found that McMYB4 is induced by treatment at 28 °C and 18 °C, and McMYB4 overexpression results in flavonol and lignin accumulation in apple leaves. Yeast one-hybrid (Y1H) assays and electrophoretic mobility shift assays (EMSAs) further revealed that McMYB4 targets the promoters of the flavonol biosynthesis genes CHS and FLS and the lignin biosynthesis genes CAD and F5H. McMYB4 expression resulted in higher levels of flavonol and lignin biosynthesis in apple during growth at 28 °C and 18 °C than during growth at 23 °C. At 28 °C and 18 °C, McMYB4 also binds to the AUX/ARF and BRI/BIN promoters to activate gene expression, resulting in acceleration of the auxin and brassinolide signaling pathways. Taken together, our results demonstrate that McMYB4 promotes flavonol biosynthesis and brassinolide signaling, which decreases ROS contents to improve plant resistance and promotes lignin biosynthesis and auxin signaling to regulate plant growth. This study suggests that McMYB4 participates in the abiotic resistance and growth of apple in response to temperature changes by regulating phenylpropanoid metabolism and hormone signaling.

中文翻译：

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McMYB4 通过调节苹果的苯丙素代谢和激素信号来改善温度适应

温度变化影响苹果的发育和生产。苯丙烷代谢和激素信号传导在调节苹果生长发育以响应温度变化方面发挥着至关重要的作用。在这里，我们发现麦克MYB4通过在 28°C 和 18°C 的处理诱导，并且麦克MYB4过表达导致苹果叶中黄酮醇和木质素的积累。酵母一杂交 (Y1H) 测定和电泳迁移率变动测定 (EMSAs) 进一步揭示 McMYB4 靶向黄酮醇生物合成基因的启动子CHS和FLS和木质素生物合成基因加元和F5H.麦克MYB4表达导致苹果在 28°C 和 18°C 生长期间比在 23°C 生长期间更高水平的黄酮醇和木质素生物合成。在 28 °C 和 18 °C 时，McMYB4 也与辅助/ARF和一带一路/斌启动子激活基因表达，导致生长素和油菜素内酯信号通路的加速。总之，我们的研究结果表明，McMYB4 促进黄酮醇生物合成和油菜素内酯信号传导，从而降低 ROS 含量以提高植物抗性，并促进木质素生物合成和生长素信号传导以调节植物生长。本研究表明，McMYB4通过调节苯丙素代谢和激素信号通路参与苹果对温度变化的非生物抗性和生长。