Genetic diversity: an ally in TALE-targeted gene predictions in the Cassava-Xanthomonas pathosystem
C. ZARATE CHAVES (1), D. Osorio Rodriguez (2), M. Buitrago Acosta (2), L. Jaimes Niño (2), A. Perez Quintero (3), S. Restrepo Restrepo (2), C. Lopez Carrascal (4), B. Szurek (3), A. Bernal Giraldo (2) (1) Universidad de los Andes. Laboratorio de micología y fitopatología LAMFU, Colombia; (2) Universidad de los Andes. Laboratorio de micología y fitopatología LAMFU, Colombia; (3) Institut de Recherche pour le Développement. Interactions Plantes-Microorganismes-Environnement (IPME), France; (4) Universidad Nacional de Colombia. Manihot Biotech., Colombia; (5) Institut de Recherche pour le Développement. Interactions Plantes-Microorganismes-Environnement (IPME), France

Xanthomonas axonopodis pv. manihotis (Xam), the causal agent of Cassava Bacterial Blight, is a major threat for cassava farmers. As in many Xanthomonas spp., pathogenicity of Xam relies on type-III secreted Transcription Activator-Like Effectors (TALEs), a group of proteins that interact with host DNA and induce the transcription of target genes (TGs), including disease-susceptibility genes. Loss-of-susceptibility alleles may be used to create resistant varieties but our knowledge about functional diversity of TALEs in Xam is still limited. This work aimed at evaluating the diversity of TALEs among 20 Xam strains isolated from different regions and time periods, and predicting potential TGs using in silico approaches. We first characterized TALE repertoires by Southern-blot analysis. Next, we cloned and sequenced over 50 TALE genes using a strategy based on DNA restriction. Our data show that the Xam TALE repertoire is limited and some effectors are conserved through time. Detailed analyses of TALE sequences showed that slight dissimilarities in residues do not change the expected affinity. We next grouped TALEs according to their binding abilities and identified candidate TGs upon in silico predictions. Finally, we performed in planta validation of these potential TGs using qRT-PCR. In conclusion, the knowledge of TALE diversity is a powerful tool to narrow the search space of TGs and this strategy can facilitate the discovery of TGs, in a faster and cost-effective way.

Abstract Number: P9-328
Session Type: Poster