Résumé
Xanthomonas bacteria cause many diseases affecting commercially important crops. MostXanthomonas species translocate Transcription Activator-Like Effectors (TALEs) into plantcells via their type III secretion system. TALEs are a unique class of bacterial effector actingas eukaryotic transcription factors to upregulate the expression of specific plant genes calledsusceptibility genes (S genes) for the bacteria benefit. According to recent studies,Xanthomonas species-specific disease management techniques can be developed bymanipulating the host S genes.SWEET genes are S genes targeted by Xanthomonas species, which encode for sugartransporters that are key to susceptibility in rice, cassava and citrus. Upregulation of thesetransporters in response to TALEs is speculated to accelerate disease development byincreasing the amount of nutrients supplied to pathogens and/or by contributing to sugarsignaling for disease resistance.We identified the repertoire of Xanthomonas tal genes from Xanthomonas campestris pv.campestris (Xcc), the causal agent of blackrot disease in Brassicaceae. To determine thetranscriptome modifications induced by the Xcc TALEs, we did RNAseq experiments incauliflower (Brassica oleracea). Interestingly, we demonstrated that Tal12a contributes toXcc virulence on cauliflower, possibly by inducing the expression of BoSWEET sugartransporters.We will present our latest results on the contribution of SWEET genes to susceptibility incauliflower.