Integrated Transcriptome and Small RNA Sequencing Analyses Reveals Insights into the Molecular Mechanism of Seed Germination in Mung Bean

During the life cycle of a plant, seed germination is crucial. Upon ingestion of water, the dry seeds resumed energy metabolism and cellular repair. To dissect the complex mechanisms at the very beginning of seed germination, two approaches including transcriptome and small RNA sequencing were conducted during the water imbibition process of mung bean seeds compared with dry seed. The transcriptome sequencing analysis identified 10,108 differentially expressed genes (DEGs) between dry and imbibed mung bean seeds. KEGG enrichment analyses demonstrated numerous DEGs involved in hormone signaling pathways, carbohydrate, and energy metabolism. Out of the total DEGs, 129 genes were investigated to involve in abscisic acid, gibberellin, and ethylene pathways, with 56 genes involved in glycolysis and TCA cycle. Through the analysis of small RNA sequencing among dif-ferent samples, there were 284 miRNAs found in the imbibed and dried seeds of mung bean containing 213 known and 71 novel miRNAs. From comparison between the two types of seeds, 51 miRNAs were differentially expressed. The integrated analyses of transcriptome and miRNAome data showed that 23 DEGs are the putative target genes of 8 miRNAs including miR156, miR171b-3p, miR166e-3p, miR169-1, etc. QRT-PCR was used to validate several DEGs and miRNAs. The data suggested that the seed imbibition process is regulated by a variety of DEGs and microRNAs. Meanwhile, we hope to gain a deeper insight into how mung bean seeds germinate in order to optimize seed growth.