Genome-Wide Analysis of the WRKY Transcription Factor Family in Roses and Their Putative Role in Defence Signalling in the Rose-Blackspot Interaction.

WRKY transcription factors are important players in plant regulatory networks, where they control and integrate various physiological processes and responses to biotic and abiotic stresses. Here, we analysed six rose genomes of 5 different species (, , , , and ) and extracted a set of 68 putative genes, extending a previously published set of 58 sequences based on the genome. Analysis of the promoter regions revealed numerous motifs related to induction by abiotic and, in some cases, biotic stressors. Transcriptomic data from leaves of two rose genotypes inoculated with the hemibiotrophic rose black spot fungus revealed the upregulation of 18 and downregulation of 9 of these genes after contact with the fungus. Notably, the resistant genotype exhibited the regulation of 25 of these genes (16 upregulated and 9 downregulated), while the susceptible genotype exhibited the regulation of 20 genes (15 upregulated and 5 downregulated). A detailed RT-qPCR analysis of , an orthologue of and , revealed induction patterns similar to those of the pathogenesis-related (PR) genes induced in salicylic acid (SA)-dependent defence pathways in black spot inoculation experiments. However, the overexpression of in rose petals did not induce the expression of any of the PR genes upon contact with black spot. However, wounding significantly induced the expression of , while heat, cold, or drought did not have a significant effect. This study provides the first evidence for the role of in rose signalling cascades and highlights the differences between and . These results improve our understanding of the regulatory function of WRKY transcription factors in plant responses to stress factors. Additionally, they provide foundational data for further studies.