Transcriptome and GWAS-based approaches to understand the mechanisms of Fusarium fujikuroi resistance in rice
Davide Spadaro: DISAFA and AGROINNOVA, University of Torino
<div><em>Fusarium fujikuroi</em>, causal agent of Bakanae disease, is the main seedborne pathogen on rice. Profiles of defense-related phytohormones and phytoalexins were investigated. In the resistant genotype Selenio, the pathogen induced high levels of sakuranetin and other phytoalexins. In the susceptible genotype Dorella, the pathogen induced gibberellins and abscisic acid, inhibited jasmonic acid, and Bakanae symptoms were observed. A RNA-seq transcriptome study was performed. The basic rice resistance machinery against <em>F. fujikuroi</em> involved PR genes, glucanases and peroxidases. The resistance mechanisms activated in the resistant cultivar included WRKY transcriptional factors, MAPK cascades, and cytochrome P450 genes. When the gibberellin production was controlled, Selenio plants activated the jasmonic acid metabolic pathway. A germplasm collection of japonica rice was screened for <em>F. fujikuroi</em> resistance, allowing the identification of accessions with high-to-moderate levels of resistance to bakanae. A genome-wide association study (GWAS) uncovered two genomic regions highly associated with the observed phenotypic variation for response to bakanae infection. A search for candidate genes with a putative role in bakanae resistance was conducted considering all the annotated genes and <em>F. fujikuroi</em>-related DEGs included in the two genomic regions highlighting several gene functions that could be involved in resistance, thus paving the way to functional characterization of the resistance loci.</div>
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