YABBY transcription factor family in the octoploid Fragaria x ananassa and five diploid Fragaria species

YABBY genes encode specific TFs of seed plants involved in development and formation of leaves, flowers, and fruit. In the present work, genome-wide and expression analyses of the YABBY gene family were performed in six species of the Fragaria genus: Fragaria x ananassa, F. daltoniana, F. nilgerrensis, F. pentaphylla, F. viridis, and F. vesca. The chromosomal location, synteny pattern, gene structure, and phylogenetic analyses were carried out. By combining RNA-seq data and RT-qPCR analysis we explored specific expression of YABBYs in F. x ananassa and F. vesca. We also analysed the promoter regions of FaYABBYs and performed MeJA application to F. x ananassa fruit to observe effects on gene expression. We identified and characterized 25 YABBY genes in F. x ananassa and six in each of the other five species, which belong to FIL/YAB3 (YABBY1), YAB2 (YABBY2), YAB5 (YABBY5), CRC, and INO clades previously described. Division of the YABBY1 clade into YABBY1.1 and YABBY1.2 subclades is reported. We observed differential expression according to tissue, where some FaYABBYs are expressed mainly in leaves and flowers and to a minor extent during fruit development of F. x ananassa. Specifically, the FaINO genes contain jasmonate-responsive cis-acting elements in their promoters which may be functional since FaINOs are upregulated in F. x ananassa fruit under MeJA treatment. This study suggests that YABBY TFs play an important role in the development- and environment-associated responses of the Fragaria genus.