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POSTERS: Plant defense response

Genetic dissection of rice resistance to sheath blight and bacterial panicle blight using recombinant inbred lines of Jupiter and Trenasse
John Christian Ontoy - Louisiana State University. Inderjit Barphagha- Department of Plant Pathology and Crop Physiology, Louisiana State University, Jong Hyun Ham- Department of Plant Pathology and Crop Physiology, Louisiana State University

Varietal development is one of the key components of managing sheath blight (SB) and bacterial panicle blight (BPB) in rice. Identifying host resistance loci through mapping is an important tool for breeding resistance. In this study, 255 recombinant inbred lines (RILs) derived from the susceptible variety Trenasse and the moderately resistant variety Jupiter were evaluated based on disease reactions for SB and BPB. Disease index score and other agronomic traits were recorded for individual RILs. Genetic linkage analysis was carried out using 170 simple sequence repeats (SSR) and single nucleotide polymorphism (SNP) markers. Composite interval mapping identified six additive quantitative trait loci (QTLs) for SB, conferring 3.1-23.5% phenotypic variations (PVE), and twelve additive QTLs for BPB, conferring 2.6-17.7% PVE. Trenasse allele had an increasing effect on most of the QTLs found for SB and BPB. The SB QTLs were located on chromosomes 2, 3, 4 and 6; while BPB QTLs were on 1, 3, 4, 5, 6, 9 and 11. One common major QTL was detected on chromosome 3 for both SB and BPB. The same QTL was also associated with heading, corresponding to 17-20% PVE. Genes found in this QTL were predicted to be involved in the signaling pathway, heading and disease resistance. Because most of the QTLs identified have small effects, marker-assisted recurrent selection should be used to accumulate favorable alleles for improving the resistance using the resistant RILs. The RILs will also provide more accurate information about the resistance mechanisms of rice for the diseases.