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Genome-wide mapping of genes controlling resistance to bakanae disease in rice

Szu-Yu Chen: Department of Plant Pathology and Microbiology, National Taiwan University

<div><em>Fusarium fujikuroi</em> causes rice bakanae disease and leads to complex symptoms, including slenderness, wide leaf angles, and elongation in plant height and internode. Although the disease affects grain yield and quality, little is known about the resistance resources and genetics in rice. The increasing occurrence and severity of the disease has been reported in several countries of Asia. In this study, we used genome-wide association study (GWAS) to identify resistance quantitative trait loci (QTLs) and genes. 231 diverse accessions from rice diversity panel 1 (RDP1) were artificially inoculated and assessed for resistance using two evaluation methods (visual rating and colonization efficiency). We identified 14 candidate QTLs and a total of 206 genes located within these regions. Among the candidate genes, eight defense-related genes [eg. nucleotide binding site–leucine-rich repeat (NBS-LRR) and dirigent (DIR) genes] and two auxin regulation genes are our top interest for further validation. Besides, one QTL was verified by linkage analysis using a population of 132 recombinant inbred lines derived from IR64 x Nipponbare. Combined GWAS and linkage analysis narrowed the QTL to an 8-kb region with three defense-related genes. This study provides useful information on the resistance performance of 231 accessions and candidate QTLs for bakanae resistance. The outcomes would help resistance breeding and uncovering resistance mechanisms in the future.</div>