College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225000, China.
Int J Mol Sci. 2022 Feb 17;23(4):2243. doi: 10.3390/ijms23042243.
Leaves, considered as the 'source' organs, depend on the development stages because of the age-dependent photosynthesis and assimilation of leaves. However, the molecular mechanisms of age-dependent limitations on the function of leaves are seldom reported. In the present study, the photosynthesis-related characteristics and photoassimilates were investigated in grape leaves at six different age groups (Ll to L6) at micro-morphological, biochemical, and molecular levels. These results showed lower expression levels of genes associated with stomatal development, and chl biosynthesis resulted in fewer stomata and lowered chlorophyll a/b contents in L1 when compared to L3 and L5. The DEGs between L5 and L3/L1 were largely distributed at stomatal movement, carbon fixation, and sucrose and starch metabolism pathways, such as (), (), (), and (, ). These genes could be major candidate genes leading to increased photosynthesis capacity and sugar content in L5. The accumulation of starch grains in the chloroplast and palisade tissue of L5 and higher transcription levels of genes related to starch biosynthesis in L5 further supported the high ability of L5 to produce photoassimilates. Hence, our results provide insights for understanding different photosynthetic functions in age-dependent leaves in grape plants at the molecular level.
叶片被认为是“源”器官，由于叶片的光合作用和同化随年龄而变化，因此其功能取决于发育阶段。然而，很少有报道涉及年龄依赖性限制叶片功能的分子机制。本研究从微观形态学、生物化学和分子水平上研究了 6 个不同年龄组（Ll 至 L6）葡萄叶片的光合作用相关特征和光产物。结果表明，与 L3 和 L5 相比，L1 中与气孔发育相关的基因表达水平较低，叶绿素生物合成导致气孔较少，叶绿素 a/b 含量降低。L5 与 L3/L1 之间的差异表达基因主要分布在气孔运动、碳固定以及蔗糖和淀粉代谢途径，如()、()、()和()。这些基因可能是导致 L5 光合作用能力和糖含量增加的主要候选基因。L5 叶绿体和栅栏组织中淀粉粒的积累以及与淀粉生物合成相关的基因转录水平较高，进一步支持了 L5 产生光产物的高能力。因此，本研究结果为在分子水平上理解葡萄植株中年龄依赖性叶片的不同光合作用功能提供了依据。
