Feng Yifeng, Tian Wenya, Guo Junjiao, Fu Jianghong, Wang Jiangbo, Wang Yan, Zhao Zhengyang
College of Horticulture and Forestry, Tarim University, Alar 843300, China.
College of Horticulture, Northwest A&F University, Yangling 712100, China.
Int J Mol Sci. 2025 May 13;26(10):4656. doi: 10.3390/ijms26104656.
Sunburn in apple peel significantly affects fruit appearance and reduces its commercial value. Previous research has shown that apple peel reduces sunburn by increasing the accumulation of proanthocyanidins (PAs) and other protective compounds. However, the precise molecular regulatory mechanism remains unclear. In this study, we systematically investigated , a key gene involved in PAs biosynthesis. We found that expression in apple peel is responsive to temperature and light fluctuations, with higher expression levels observed under increased temperature and light exposure. Functional analysis revealed that overexpression in apple peel and callus enhanced resistance to high-temperature and -light-intensity stress, accompanied by a corresponding increase in PAs and chlorogenic acid contents. In addition, we demonstrated that MdMYBR9 can activate promoter activity and promote its expression through yeast one-hybrid, dual-luciferase, and electrophoretic mobility transfer experiments. The results indicated that was an upstream regulator of . Based on these findings, this study proposes the regulatory model for apple sunburn resistance, providing a molecular framework for enhancing sunburn tolerance in apple breeding programs.
苹果果皮晒伤会显著影响果实外观并降低其商业价值。先前的研究表明，苹果果皮通过增加原花青素（PAs）和其他保护化合物的积累来减轻晒伤。然而，精确的分子调控机制仍不清楚。在本研究中，我们系统地研究了参与PAs生物合成的关键基因。我们发现该基因在苹果果皮中的表达对温度和光照波动有响应，在温度升高和光照增强的条件下观察到更高的表达水平。功能分析表明，该基因在苹果果皮和愈伤组织中的过表达增强了对高温和高光强胁迫的抗性，同时伴随着PAs和绿原酸含量的相应增加。此外，我们通过酵母单杂交、双荧光素酶和电泳迁移率转移实验证明，MdMYBR9可以激活该基因的启动子活性并促进其表达。结果表明，MdMYBR9是该基因的上游调节因子。基于这些发现，本研究提出了苹果抗晒伤的调控模型，为苹果育种计划中提高晒伤耐受性提供了分子框架。
