Relationship between Protein, MicroRNA Expression in Extracellular Vesicles and Rice Seed Vigor.

Plant extracellular vesicles are non-self-replicating particles released by living plant cells and delimited by a lipid bilayer. They contain a large amount of lipids, RNA, and proteins. Seed vigor plays an important role in agricultural production and preservation of germplasm resources. Extracellular vesicles with cross-species communication with bioactive molecules can resist pathogens, exhibit anti-aging properties, and perform other functions; however, its potential influence on seed vigor has not been reported. In this study, rice seeds with different germination percentages were used to extract extracellular vesicles, endogenous proteins, and RNA. Protein qualitative identification and miRNA differential analysis were performed to analyze the regulatory mechanism of extracellular vesicles on seed vigor. Results: The profiles of four miRNA families were found to be significantly different: osa-miR164, osa-miR168, osa-miR166, and osa-miR159. Protein correlation analysis predicted that extracellular vesicles might mediate the synthesis of the seed cell wall; glyoxic acid cycle and tricarboxylic acid cycle; non-specific lipid transfer; mitochondrial quality control; and other biological processes to regulate rice seed viability. In addition, cupin protein, phospholipase D, aldehyde dehydrogenase, seven heat shock proteins (especially BiP1 and BiP2), protein disulfide isomerase-like (PDI), thioredoxin, calnexin and calreticulin, glutathione transferase, and other proteins found in extracellular vesicles were closely related to seed vigor. This provides a novel direction for the study of the regulation mechanism of seed vigor.