Key Laboratory of Ministry of Education for Genetic Improvement and Comprehensive Utilization of Crops, Fujian Provincial Key Laboratory of Crop Breeding by Design, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
Postdoctoral Station of Biology, School of Life Sciences, Hebei University, Baoding, 071000, Hebei, China.
BMC Plant Biol. 2022 Mar 23;22(1):137. doi: 10.1186/s12870-022-03510-2.
The normal metabolism of transitory starch in leaves plays an important role in ensuring photosynthesis, delaying senescence and maintaining high yield in crops. OsCKI1 (casein kinase I1) plays crucial regulatory roles in multiple important physiological processes, including root development, hormonal signaling and low temperature-treatment adaptive growth in rice; however, its potential role in regulating temporary starch metabolism or premature leaf senescence remains unclear. To reveal the molecular regulatory mechanism of OsCKI1 in rice leaves, physiological, transcriptomic and proteomic analyses of leaves of osckI1 allele mutant lses1 (leaf starch excess and senescence 1) and its wild-type varieties (WT) were performed.
Phenotypic identification and physiological measurements showed that the lses1 mutant exhibited starch excess in the leaves and an obvious leaf tip withering phenotype as well as high ROS and MDA contents, low chlorophyll content and protective enzyme activities compared to WT. The correlation analyses between protein and mRNA abundance are weak or limited. However, the changes of several important genes related to carbohydrate metabolism and apoptosis at the mRNA and protein levels were consistent. The protein-protein interaction (PPI) network might play accessory roles in promoting premature senescence of lses1 leaves. Comprehensive transcriptomic and proteomic analysis indicated that multiple key genes/proteins related to starch and sugar metabolism, apoptosis and ABA signaling exhibited significant differential expression. Abnormal increase in temporary starch was highly correlated with the expression of starch biosynthesis-related genes, which might be the main factor that causes premature leaf senescence and changes in multiple metabolic levels in leaves of lses1. In addition, four proteins associated with ABA accumulation and signaling, and three CKI potential target proteins related to starch biosynthesis were up-regulated in the lses1 mutant, suggesting that LSES1 may affect temporary starch accumulation and premature leaf senescence through phosphorylation crosstalk ABA signaling and starch anabolic pathways.
The current study established the high correlation between the changes in physiological characteristics and mRNA and protein expression profiles in lses1 leaves, and emphasized the positive effect of excessive starch on accelerating premature leaf senescence. The expression patterns of genes/proteins related to starch biosynthesis and ABA signaling were analyzed via transcriptomes and proteomes, which provided a novel direction and research basis for the subsequent exploration of the regulation mechanism of temporary starch and apoptosis via LSES1/OsCKI1 in rice.
叶片中转瞬即逝淀粉的正常代谢对于确保光合作用、延缓衰老和维持作物高产至关重要。OsCKI1（酪蛋白激酶 I1）在包括根系发育、激素信号和低温处理适应性生长在内的多个重要生理过程中发挥着关键的调节作用；然而，其在调节临时淀粉代谢或过早叶片衰老方面的潜在作用尚不清楚。为了揭示 OsCKI1 在水稻叶片中的分子调控机制，对 osckI1 等位基因突变体 lses1（叶片淀粉过剩和衰老 1）及其野生型品种（WT）的叶片进行了生理学、转录组学和蛋白质组学分析。
表型鉴定和生理测量表明，与 WT 相比，les1 突变体叶片中淀粉过剩，叶片尖端枯萎明显，ROS 和 MDA 含量高，叶绿素含量和保护酶活性低。蛋白质丰度与 mRNA 丰度之间的相关性较弱或有限。然而，几种与碳水化合物代谢和细胞凋亡相关的重要基因在 mRNA 和蛋白质水平上的变化是一致的。蛋白质-蛋白质相互作用（PPI）网络可能在促进 lses1 叶片过早衰老中发挥辅助作用。综合转录组学和蛋白质组学分析表明，与淀粉和糖代谢、细胞凋亡和 ABA 信号转导相关的多个关键基因/蛋白表达差异显著。瞬态淀粉的异常增加与淀粉合成相关基因的表达高度相关，这可能是导致 lses1 叶片过早衰老和多个代谢水平变化的主要因素。此外，ABA 积累和信号转导相关的 4 种蛋白和与淀粉生物合成相关的 3 种 CKI 潜在靶蛋白在 lses1 突变体中上调，表明 LSES1 可能通过磷酸化交叉对话 ABA 信号转导和淀粉合成途径影响临时淀粉的积累和过早的叶片衰老。
本研究建立了 lses1 叶片生理特征变化与 mRNA 和蛋白质表达谱之间的高度相关性，并强调了过量淀粉对加速叶片过早衰老的积极作用。通过转录组学和蛋白质组学分析了与淀粉生物合成和 ABA 信号转导相关的基因/蛋白的表达模式，为后续通过 LSES1/OsCKI1 探索水稻中转瞬即逝淀粉和细胞凋亡的调控机制提供了新的方向和研究基础。
