The MYB proteins comprise one of the largest families of plant transcription factors (TFs) and many of MYB families, which play essential roles in plant growth, development and respond to environmental stresses, and have yet been identified in plant. Previous research has shown that miR159 family members repressed the conserved plant R2R3 MYB domain TFs in model plants. In the present research, we identified three potato novel miR159 family members named as stu-miR159a, stu-miR159b and stu-miR159c based on bioinformatics analysis. Target prediction showed that they have a bite sit on the three GAMyb-like genes (StGAMyb-like1, StGAMyb-like2.1 and StGAMyb-like2.2) of potato. Those GAMyb-like genes also have been selected and cloned from potato, which belong to R2R3 MYB domain TFs. We further measured expressional levels of stu-miR159s and potato GAMyb-like genes during the different periods of drought treated samples using quantitative real-time PCR (qRT-PCR). The results showed that they had a opposite expression pattern, briefly, three stu-miR159 members showed similar expressional trends which were significantly decreased expression after experiencing 25 days of drought stress treatment, while the potato GAMyb-like family members were greatly increased. Therefore, we suggested that stu-miR159s negatively regulated the expression of potato GAMyb-like genes which responsible for drought stress. The findings can facilitate functional studies of miRNAs in plants and provide molecular evidence for involvement process of drought tolerance in potato. 
Identification of miR159s and their target genes and expression analysis under drought stress in potato