College of Horticulture, Northwest A & F University, Yangling, 712100, China.
Howard Hughes Medical Institute, Duke University, Durham, NC, 27708, USA.
Planta. 2024 Nov 22;261(1):1. doi: 10.1007/s00425-024-04575-z.
Starch degradation, a crucial source for soluble sugar, significantly influences fruit flavor development during ripening. Key enzymes in this process include α-amylases (AMYs) and β-amylases (BAMs). In this study, we identified 5 PpAMYs and 9 PpBAMs in peach and categorized them into three and four groups, respectively, based on the gene structures and the phylogenetic analysis. Subsequent expression analysis revealed that elevated levels of PpAMY1, PpAMY5, and PpBAM2 were detected in the middle and late stages of fruit development, suggesting their positive involvement in starch degradation during peach fruit ripening. Transient overexpression experiments conducted in peach fruits and callus further demonstrated that overexpression of PpBAM2 significantly reduced starch content, indicating its important role in starch degradation during peach fruit ripening. Furthermore, we identified a R2R3-MYB transcription factor, PpMYB10.1, which activated the expression of PpBAM2 through the direct interacting with its promoter. In addition, transient overexpression of PpMYB10.1 could significantly reduce starch content in peach callus. Consequently, our findings highlight the positive role of PpBAM2 in peach starch degradation, with PpMYB10.1 serving as an activator during this process.
淀粉降解是可溶性糖的重要来源，对果实成熟过程中的风味发育有重要影响。该过程中的关键酶包括α-淀粉酶（AMYs）和β-淀粉酶（BAMs）。本研究在桃中鉴定到 5 个 PpAMYs 和 9 个 PpBAMs，根据基因结构和系统进化分析将其分别归类为 3 组和 4 组。随后的表达分析表明，在果实发育的中后期检测到 PpAMY1、PpAMY5 和 PpBAM2 的表达水平升高，表明它们在桃果实成熟过程中积极参与淀粉降解。在桃果实和愈伤组织中的瞬时过表达实验进一步表明，过表达 PpBAM2 可显著降低淀粉含量，表明其在桃果实成熟过程中淀粉降解中的重要作用。此外，我们鉴定到一个 R2R3-MYB 转录因子 PpMYB10.1，它通过与启动子直接相互作用来激活 PpBAM2 的表达。此外，瞬时过表达 PpMYB10.1 可显著降低桃愈伤组织中的淀粉含量。因此，我们的研究结果强调了 PpBAM2 在桃淀粉降解中的积极作用，PpMYB10.1 作为该过程中的激活子。
