Induction of common beanOVATE Family Protein 7(PvOFP7) promotes resistance to common bacterial blight

Abstract

Common bacterial blight of bean (CBB) is a devastating seed-transmitted disease caused byXanthomonas phaseolipv.phaseoliandXanthomonas citripv.fuscanson common bean (Phaseolus vulgarisL.). The genes responsible for CBB resistance are largely unknown. moreover, the lack of reproducible and universal transformation protocol limits the study and improvement of genetic traits in common bean. We producedX. phaseolipv.phaseolistrains expressing artificially-designed Transcription-Activator Like Effectors (dTALEs) to target 14 candidate genes and performedin plantaassays in a susceptible common bean genotype to analyse if the transcriptional induction of these genes could confer resistance to CBB. Induction ofPvOFP7,PvAP2-ERF71andPvExpansinA17resulted in CBB symptom reduction. In particular,PvOFP7induction led to strong symptom reduction, linked to reduced bacterial growthin plantaat early colonisation stages. RNA-Seq analysis revealed up-regulation of cell wall formation and primary metabolism, and major down-regulation of Heat Shock Proteins. Our results demonstrate that PvOFP7 is contributes to CBB resistance, and underline the usefulness of dTALEs for highlighting genes of quantitative activity.