Genome-wide characterization and expression analysis of WRKY family genes during development and resistance to Colletotrichum fructicola in cultivated strawberry (Fragariaxananassa Duch.)

Based on the recently published whole-genome sequence of cultivated strawberry 'Camarosa', in this study, 222 FaWRKY genes were identified in the 'Camarosa' genome. Phylogenetic analysis showed that the 222 FaWRKY candidate genes were classified into three groups, of which 41 were in group I, 142 were in group II, and 39 were in group III. The 222 FaWRKY genes were evenly distributed among the seven chromosomes. The exon-intron structures and motifs of the WRKY genes had evolutionary diversity in different cultivated strawberry genomes. Regarding differential expression, the expression of FaWRKY133 was relatively high in leaves, while FaWRKY63 was specifically expressed in roots. FaWRKY207, 59, 46, 182, 156, 58, 39, 62 and 115 were up-regulated during achene development from the green to red fruit transition. FaWRK181, 166 and 211 were highly expressed in receptacles at the ripe fruit stage. One interesting finding was that FaWRKY179 and 205 were significantly repressed after Colletotrichum fructicola inoculation in both 'Benihoppe' and 'Sweet Charlie' compared with Mock. The data reported here provide a foundation for further comparative genomics and analyses of the distinct expression patterns of FaWRKY genes in various tissues and in response to C. fructicola inoculation.