Integrated transcriptome and small RNA sequencing analyses reveals insights into the molecular mechanism of seed germination in mung bean

Seed germination plays a pivotal role during the life cycle of plants. When the dry seeds imbibed water, the resumption of energy metabolism and cellular repair occurred. To dissect the complex mechanisms during the very early stage of seed germination, two approaches including transcriptome and small RNA sequencing were analyzed during the water imbibition process of mung bean seeds compared with dry seeds. 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 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 different samples, a total of 284 miRNAs containing 213 known and 71 novel ones were identified between mung bean imbibed and dry seeds. From comparison between the two types of seeds, 51 miRNAs indicated differentially expressed. The integrated analyses of transcriptome and miRNAome data showed that 23 differentially expressed genes are the putative target genes of 8 miRNAs including miR156, miR171b-3p, miR166e-3p, miR169-1 , etc. Several differentially expressed genes and miRNAs were selected for validation by quantitative RT-PCR. We hope this analysis will provide novel insights for the study of molecular mechanism of seed germination in mung bean.