Zhang Di, Liu Tao, Sheng Jiangyuan, Lv Shan, Ren Li
School of Design, Shanghai Jiao Tong University, Shanghai, China.
Institute for Agri-Food Standards and Testing Technology, Shanghai Academy of Agricultural Sciences, Shanghai, China.
Front Plant Sci. 2021 Dec 17;12:792057. doi: 10.3389/fpls.2021.792057. eCollection 2021.
Lotus is an aquatic plant that is sensitive to water loss, but its seeds are longevous after seed embryo dehydration and maturation. The great difference between the responses of vegetative organs and seeds to dehydration is related to the special protective mechanism in embryos. In this study, tandem mass tags (TMT)-labeled proteomics and parallel reaction monitoring (PRM) technologies were used to obtain novel insights into the physiological regulatory networks during lotus seed dehydration process. Totally, 60,266 secondary spectra and 32,093 unique peptides were detected. A total of 5,477 proteins and 815 differentially expressed proteins (DEPs) were identified based on TMT data. Of these, 582 DEPs were continuously downregulated and 228 proteins were significantly up-regulated during the whole dehydration process. Bioinformatics and protein-protein interaction network analyses indicated that carbohydrate metabolism (including glycolysis/gluconeogenesis, galactose, starch and sucrose metabolism, pentose phosphate pathway, and cell wall organization), protein processing in ER, DNA repair, and antioxidative events had positive responses to lotus embryo dehydration. On the contrary, energy metabolism (metabolic pathway, photosynthesis, pyruvate metabolism, fatty acid biosynthesis) and secondary metabolism (terpenoid backbone, steroid, flavonoid biosynthesis) gradually become static status during lotus embryo water loss and maturation. Furthermore, non-enzymatic antioxidants and pentose phosphate pathway play major roles in antioxidant protection during dehydration process in lotus embryo. Abscisic acid (ABA) signaling and the accumulation of oligosaccharides, late embryogenesis abundant proteins, and heat shock proteins may be the key factors to ensure the continuous dehydration and storage tolerance of lotus seed embryo. Stress physiology detection showed that HO was the main reactive oxygen species (ROS) component inducing oxidative stress damage, and glutathione and vitamin E acted as the major antioxidant to maintain the REDOX balance of lotus embryo during the dehydration process. These results provide new insights to reveal the physiological regulatory networks of the protective mechanism of embryo dehydration in lotus.
莲是一种对水分流失敏感的水生植物，但其种子在种胚脱水成熟后寿命很长。营养器官和种子对脱水反应的巨大差异与胚中的特殊保护机制有关。在本研究中，采用串联质谱标签（TMT）标记蛋白质组学和平行反应监测（PRM）技术，以深入了解莲子脱水过程中的生理调控网络。总共检测到60266个二级谱和32093个独特肽段。基于TMT数据鉴定出总共5477种蛋白质和815种差异表达蛋白（DEP）。其中，在整个脱水过程中，582个DEP持续下调，228种蛋白质显著上调。生物信息学和蛋白质-蛋白质相互作用网络分析表明，碳水化合物代谢（包括糖酵解/糖异生、半乳糖、淀粉和蔗糖代谢、磷酸戊糖途径以及细胞壁组织）、内质网中的蛋白质加工、DNA修复和抗氧化事件对莲胚脱水有积极反应。相反，在莲胚失水和成熟过程中，能量代谢（代谢途径、光合作用、丙酮酸代谢、脂肪酸生物合成）和次生代谢（萜类骨架、类固醇、类黄酮生物合成）逐渐处于静止状态。此外，非酶抗氧化剂和磷酸戊糖途径在莲胚脱水过程中的抗氧化保护中起主要作用。脱落酸（ABA）信号传导以及寡糖、晚期胚胎丰富蛋白和热休克蛋白的积累可能是确保莲子胚持续脱水和储存耐受性的关键因素。胁迫生理学检测表明，HO是诱导氧化应激损伤的主要活性氧（ROS）成分，谷胱甘肽和维生素E作为主要抗氧化剂在脱水过程中维持莲胚的氧化还原平衡。这些结果为揭示莲胚脱水保护机制的生理调控网络提供了新的见解。
