IDENTIFICATION AND CHARACTERIZATION OF DIFFERENTIALLY EXPRESSED MICRORNAS DURING FRUIT RIPENING IN PINEAPPLE (ANANAS COMOSUS VAR. COMOSUS)

MicroRNAs (miRNAs) are a class of small, non-coding, endogenous RNAs that negatively regulates gene expression by cleaving or repressing the translational process of protein-coding mRNA transcripts. To determine if pineapple fruit development and ripening was mediated by miRNA, miRNA were detected and quantified at pre- and post-ripening stages using RT-qPCR. The expression profiles of 13 miRNAs namely miR156, miR157, miR159, miR162, miR164, miR165, miR167, miR168, miR169, miR170, miR171, miR172, and miR390 were detected in pineapple. Among these 13 miRNAs, only the genes (miR168, miR390, and miR164) displayed clear differential expression during pre-ripening and post-ripening stages of the fruit. During the post-ripening stage, miR168 and miR390 were up-regulated 1.79- and 2.64-fold, respectively, while expression of miR164 dropped to 0.07-fold compared to the pre-ripening stage. The discovery of miRNAs from this study together with its stage-regulated expression profiles are excellent candidates for further investigation into pineapple crop improvement through functional genomes.