miRNAs play important roles in aroma weakening during the shelf life of ‘Nanguo’ pear after cold storage

Cold storage is commonly employed to delay senescence in ‘Nanguo’ pears after harvest. However, this technique also causes fruit aroma weakening. MicroRNAs play important roles in plant development and in eliciting responses to abiotic environmental stressors. In this study, the miRNA transcript profile of the fruit at the first day (C0, LT0) move in and out of cold storage and the optimum tasting period (COTP, LTOTP) during shelf life at room temperature were analyzed, respectively. More than 300 known miRNAs were identified in ‘Nanguo’ pears; 176 and 135 miRNAs were significantly differentially expressed on the C0 vs . LT0 and on the COTP vs. LTOTP, respectively. After prediction the target genes of these miRNAs, LOX2S , LOX1_5 , HPL , and ADH1 were found differentially expressed, which were the key genes during aroma formation. The expression pattern of these target genes and the related miRNAs were identified by RT-PCR. Mdm-miR172a-h, mdm-miR159a/b/c, mdm-miR160a-e, mdm-miR395a-i, mdm/ppe-miR399a, mdm/ppe-miR535a/b, and mdm-miR7120a/b negatively regulated target gene expression. These results indicate that miRNAs play key roles in aroma weakening in refrigerated ‘Nanguo’ pear and provide valuable information for studying the molecular mechanisms of miRNAs in the aroma weakening of fruits due to cold storage.