Study : Cassava responses to Pathogenic and non-pathogenic Xanthomonas axonopodis pv manihotis


Cassava responses to Pathogenic and non-pathogenic Xanthomonas axonopodis pv manihotis
Xanthomonas axonopodis pv. manihotis (Xam) is a gram negative bacterium causing Cassava Bacterial Blight (CBB), an important limitation for cassava production. The genetic bases underlying cassava resistance and susceptibility to different Xam strains are currently unknown. To identify genes and pathways important for the interaction, we used RNA-seq data to study transcriptomic changes in cassava plants inoculated with the non-pathogenic Xam strain, (ORST4) and a pathogenic strain, ORST4 transformed with the TAL effector TALE1Xam (ORST4+TALE1Xam). This analysis revealed that transcriptomic responses to both strains were very similar and were dominated by the induction of genes related to photosynthesis and phenylpropanoid biosynthesis and the down-regulation of genes related to jasmonic acid signaling, features possibly related to defense responses. Among the genes induced exclusively in cassava plants inoculated with ORST4 + TALE1Xam we found one gene containing a predicted binding site for TALE1Xam in its promoter region. This gene encodes for a Heat Shock Transcription Factor B3 (HsfB3) and likely acts a transcriptional repressor. HsfB3 may constitute a new type of susceptibility gene activated by a TAL effector that manages to be sufficient for symptom development without suppressing defense responses in the plant. Overall design: mRNA of Cassava stems inoculated with a non-pathogenic (ORST4) and pathogenic (+TALE1Xam) strain of Xanthomonas axonopodis pv. Manihotis, tissues collected at 0, 5 and7 days post-inoculation, 2 technical replicates used


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