Prediction And Validation Of Conservative MicroRNAs Of Solanum Tuberosum L.

MicroRNAs (miRNAs) are endogenous approximate 22 nucleotide small RNAs that play important regulatory roles in animals and plants by targeting mRNAs for cleavage or translational repression. The known plant miRNAs have a remarkable penchant for targeting transcription factor gene families, particularly those with known or suspected roles in developmental patterning or cell differentiation. More and more researches have demonstrated that many miRNAs regulate various plant developmental processes, including leaf morphogenesis and polarity, floral differentiation and development, root initiation and development, vascular development, regulation of hormone-mediated signal transduction and environmental stress responses.Potato (Solanum tuberosum) is an important crop around the world, and accounts for a significant amount of the food consumed by humans. So far, about 16.1% of the sequencing of the potato genome has been completed. Although a large number of plant miRNAs have been documented in recent years, mainly by cloning or computational approaches, only limited miRNAs have been reported in potato.?In the present study, computational prediction of potential miRNAs from potato revealed 71 miRNAs belonging to 48 families. Amongst these 71 miRNAs, 65 were predicted for the first time. Most potato miRNA families have one to three members, and sequence analysis showed that the candidate pre-miRNA sequences varied from 48-224 bp in length.To verify the predicted miRNAs, specific stem-loop RT primers were designed and real-time PCR assays were used to profile the expression levels of seven miRNAs and their target mRNAs from different tissues of potato. The results showed that all the selected miRNAs were successfully amplified. Most of the detected miRNAs had their highest expression levels in leaves, and the lowest levels in the stem, while miR159 and miR164 presented a different expression pattern. The specific expression levels of each miRNAs in the tested tissues might be related to their particular functions in regulating potato vegetative growth and organ development. In addition, the targets MYB, ARF8 and AGO1 were also successfully amplified, each potential target mRNA exhibited a specific expression pattern in different tissues. The comparative expression level of each target mRNA was coherent with that been reported in the model plants, such as Arabidopsis, which indicated that the relevant miRNAs might have similar functions in regulating the vegetative development of potato.