Common bean resistance to Xanthomonas is associated with upregulation of the salicylic acid pathway and downregulation of photosynthesis.

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background:</jats:bold> Common bacterial blight (CBB) caused by <jats:italic>Xanthomonas phaseoli </jats:italic>pv. <jats:italic>phaseoli</jats:italic> and <jats:italic>Xanthomonas citri</jats:italic> pv. <jats:italic>fuscans</jats:italic> is one of the major threats to common bean crops (<jats:italic>Phaseolus vulgaris</jats:italic> L.). Resistance to CBB is particularly complex as 26 quantitative resistance loci to CBB have been described so far. To date, transcriptomic studies after CBB infection have been very scarce and the molecular mechanisms underlying susceptibility or resistance are largely unknown. <jats:bold>Results:</jats:bold> We sequenced and annotated the genomes of two common bean genotypes being either resistant (BAT93) or susceptible (JaloEEP558) to CBB. Reciprocal BLASTp analysis led to a list of 20,787 homologs between these genotypes and the common bean reference genome (G19833), which provides a solid dataset for further comparative analyses. RNA-Seq after inoculation with <jats:italic>X. phaseoli </jats:italic>pv. <jats:italic>phaseoli</jats:italic> showed that the susceptible genotype initiated a more intense and diverse biological response than the resistant genotype. Resistance was linked to upregulation of the salicylic acid pathway and downregulation of photosynthesis and sugar metabolism, while susceptibility was linked to downregulation of resistance genes and upregulation of the ethylene pathway and of genes involved in cell wall modification. <jats:bold>Conclusions:</jats:bold> This study helps better understanding the mechanisms occurring during the early colonization phase of common bean by <jats:italic>Xanthomonas</jats:italic> and unveils new actors potentially important for resistance and susceptibility to CBB. We discuss the potential link between the pathways induced during bean colonization and genes induced by transcription activator-like effectors (TALEs), as illustrated in other <jats:italic>Xanthomonas</jats:italic> pathovars.</jats:p>

An ERF transcription factor from Brassica oleracea: a new member of the emerging pathogenicity hub in plant-Xanthomonas interactions

“…ERF upregulation was also characteristic of the susceptible interaction between common bean and Xanthomonas phaseoli pv. phaseoli (Foucher et al, 2020). Interestingly, type III effector-dependent activation of many AP2/ERF transcription factors was observed in Arabidopsis thaliana upon Pseudomonas syringae pv.…”