Fan-miR159 Family Targets Two Types of Genes to Potentially Regulate the Development of Strawberry

MicroRNAs (miRNAs) represent the most abundant class of small RNAs in plants, in which the miR159 family demonstrates a high degree of conservation across various plant species and plays a crucial role in regulating anther, silique, and seed development by targeting GAMYB-like. The members of the Fan-miR159 family in cultivated strawberry target not only GAMYB-like genes but also Auxin Response Factor (ARF) family members, which are annotated as “ARF23-like” in the genome. In this study, we firstly analyzed the structural features, evolutionary conservation, and expression patterns of the miR159 family in Fragaria × ananassa. Then, we reannotated the “ARF23-like” genes in cultivated strawberry and found that they actually belong to the “ARF2b” subfamily. Finally, we utilized RT-qPCR and co-transformation experiments to analyze and validate our observation. The results showed the suppression of FaARF2b-2 expression by fan-miR159n and fan-miR159r in both tobacco and strawberry. Moreover, two transcripts of the FaARF2b-2 gene were detected in cultivated strawberry, FaARF2b-2R and FaARF2b-2M. The expression levels of both FaARF2b-2M and FaARF2b-2R increased following the abscisic acid (ABA) treatment, indicating that they may be positively regulated by ABA. In addition, FaARF2b-2M exhibits significantly higher expression levels in the anther compared to FaARF2b-2R, which potentially plays an important role in the male reproductive development. Our findings enhance the understanding of the miR159 family in cultivated strawberry and expand the knowledge regarding its novel targets.