Abstract

Bacterial blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) drives severe yield and quality losses in rice (Oryza sativa Xa1, Xa3/Xa26, xa5, xa13, Xa21, and Xa27). Here we employ a transcriptomics approach to elucidate the Xa21-, NH1- (NPR1 homolog 1) (NH1)-, and NRR- (negative regulator of disease resistance) mediated defense response to Xoo. Among the candidate genes, we focused on 288 genes showing significant change in at least two of the above comparisons to support the association with an enhanced defense response. Gene Ontology enrichment analysis for this gene list revealed that response to biotic stimulus was 25.0-fold more enriched compared to the control, well qualifying the candidate genes for enhanced resistant response. The biotic stress overview installed in the MapMan toolkit was used to identify diverse components consisting of defense signaling pathways such as genes involved in disease resistance, redox, signaling, regulation of transcription, pathogenesis-related functions, secondary metabolism, and protein degradation. Of these, we validated the expression patterns of genes related to regulation of transcription and pathogenesis-related functions and suggest a functional network model for WRKY transcription factors mediating defense signaling pathways against Xoo. We expect that our analysis will contribute to increasing the depth of knowledge on the molecular mechanism for enhanced disease resistance against bacterial blight disease in rice.

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