Jia Xumei, Xu Shuo, Wang Fei, Jia Yiwei, Qing Yubin, Gao Tengteng, Zhang Zhijun, Liu Xiaomin, Yang Chao, Ma Fengwang, Li Chao
State Key Laboratory for Crop Stress Resistance and High-Efficiency Production/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China.
Hortic Res. 2024 Jul 11;11(8):uhae192. doi: 10.1093/hr/uhae192. eCollection 2024 Aug.
Plants experience various age-dependent changes during juvenile to adult vegetative phase. However, the regulatory mechanisms orchestrating the changes remain largely unknown in apple (). This study showed that tissue-cultured apple plants at juvenile, transition, and adult phase exhibit age-dependent changes in their plant growth, photosynthetic performance, hormone levels, and carbon distribution. Moreover, this study identified an age-dependent gene, sorbitol dehydrogenase (), a key enzyme for sorbitol catabolism, highly expressed in the juvenile phase in apple. Silencing in apple significantly decreased the plant growth and GA3 levels. However, exogenous GA3 rescued the reduced plant growth phenotype of TRV-. Biochemical analysis revealed that MdSPL1 interacts with MdWRKY24 and synergistically enhance the repression of MdSPL1 and MdWRKY24 on , thereby promoting sorbitol accumulation during vegetative phase change. Exogenous sorbitol application indicated that sorbitol promotes the transcription of and . Notably, MdSPL1-MdWRKY24 module functions as key repressor to regulate GA-responsive gene, Gibberellic Acid-Stimulated () expression, thereby leading to a shift from the quick to the slow-growth strategy. These results reveal the pivotal role of sorbitol in controlling apple plant growth, thereby improving our understanding of vegetative phase change in apple.
植物在从幼年期到成年营养期会经历各种与年龄相关的变化。然而，在苹果中，协调这些变化的调控机制在很大程度上仍不清楚。本研究表明，处于幼年期、过渡期和成年期的组织培养苹果植株在植物生长、光合性能、激素水平和碳分配方面表现出与年龄相关的变化。此外，本研究鉴定出一个与年龄相关的基因——山梨醇脱氢酶（），它是山梨醇分解代谢的关键酶，在苹果幼年期高度表达。在苹果中沉默该基因显著降低了植株生长和赤霉素3（GA3）水平。然而，外源GA3挽救了TRV-植株生长受抑制的表型。生化分析表明，MdSPL1与MdWRKY24相互作用，并协同增强MdSPL1和MdWRKY24对该基因的抑制作用，从而在营养生长期变化过程中促进山梨醇积累。外源施加山梨醇表明，山梨醇促进该基因和另一基因的转录。值得注意的是，MdSPL1-MdWRKY24模块作为关键阻遏物发挥作用，调控GA响应基因——赤霉素刺激基因（）的表达，从而导致从快速生长策略向缓慢生长策略的转变。这些结果揭示了山梨醇在控制苹果植株生长中的关键作用，从而增进了我们对苹果营养生长期变化的理解。
