Résumé
The Xanthomonas genus includes several plant pathogens responsible for significant crop losses worldwide. Most of the functional studies of virulence in this genus have been carried out by directed mutagenesis through homologous recombination. However, this strategy is cumbersome for the study of gene families. CRISPR interference (CRISPRi) allows precise silencing of target genes by using a catalytically dead Cas9 (dCas9) which interferes with gene expression. Because of its RNA-directed nature, this technology can be used for silencing several genes in a single experiment in bacteria and other organisms. We implemented a CRISPRi strategy to silence several members of the Transcriptional activatorlike effectors (TALE) gene family at once in four different species of Xanthomonas. Our results underscore the importance of the activation of the SWEET gene family in cassava upon infection by Xanthomonas phaseoli pv. manihotis. Remarkably, we report the importance of this gene family in the infection of this host by the non-vascular pathogen X. cassavae. In addition, we successfully silenced several TALE genes in a total of five species, including X. oryzae pv. oryzae, X. citri pv. citri and X. campestris pv. campestris using CRISPRi, confirming the importance of this gene family in these pathosystems. The CRISPRi tool can be further modulated to silence sets of genes within a gene family for functional studies in Xanthomonas and other plant pathogenic bacteria.