Uncovering the miRNA-mediated regulatory network involved in postharvest senescence of grape berries

The postharvest senescence phase of table grapes comprises a series of biological processes. MicroRNAs (miRNAs) regulate downstream genes at the post-transcriptional level; however, whether miRNAs are involved in postharvest grape senescence remains unclear. We used small RNA sequencing to identify postharvest-related miRNAs in ‘Red Globe’ ( Vitis vinifera ) grapes harvested after 0, 30, and 60 d at 4 °C (RG0, RG30, RG60). In total, 42 known and 219 novel miRNA candidates were obtained. During fruit senescence, the expression of PC-3p-3343_1921, miR2950, miR395k, miR2111, miR159c, miR169q, PC-5p-1112_4500, and miR167b changed significantly (p<0.05). Degradation sequencing identified 218 targets associated with cell wall organization, TCA cycling, pathogen defense, carbon metabolism, hormone signaling, the anthocyanin metabolism pathway, and energy regulation, of which ARF6, GRF3, TCP2, CP1, MYBA2, and WRKY72 were closely related to fruit senescence. We also verified VIT_00s2146g00010, VIT_02s0012g01750, and VIT_03s0038g00160 with unknown functions cleaved by senescence-related PC-5p-1112_4500 via the dual luciferase assay and transient transformation of grape berries and showed that they regulate berry senescence. These results deepen the understanding of the contribution of miRNAs in regulating grape berry senescence and prolonging the shelf life of horticultural products. Based on these results, we propose a new theoretical strategy to delay the postharvest senescence of horticultural products by regulating the expression of key miRNAs (e.g., PC-5p-1112_4500), thereby extending their shelf life.