Skip to main content
APS Plant Health 2025 Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.

POSTERS: Genetics of Resistance II

P-266 - Identification and introgression of novel sheath blight resistance QTLs into elite rice cultivars

Tuesday, August 5, 2025
9:30 AM - 10:15 AM HST
Location: Exhibit Hall 3
Abstract Text: Sheath blight (ShB), caused by the soil-borne necrotrophic pathogen Rhizoctonia solani, is one of the most destructive fungal diseases globally. Resistance to ShB is polygenic, with numerous minor genes interacting with environmental factors that influence the disease expression. To address this complex trait, we evaluated key disease components, including lesion number, maximum lesion length, and vertical sheath colonization. Screening 3,470 accessions and lines derived from landraces and wild rice identified 17 novel resistance sources. A genome-wide association study (GWAS) of 228 O. sativa accessions revealed eight additional resistant landraces and two significant quantitative trait loci (QTLs) on chromosome 11. To enhance resistance, a multi-way cross was done to pyramid these QTLs with ShB6, a highly resistant line derived from O. rufipogon. This approach yielded 15 resistant lines, with eight performing comparatively or better than those of the resistant donors under controlled screening. Furthermore, at least 15 candidate genes associated with plant innate immunity were localized within the identified QTLs. On the pathogen side, we assembled an R. solani reference genome using long-read next-generation sequencing (NGS) of a Philippine isolate (LR01) and identified 22 candidate effector genes highly expressed in planta. In summary, our findings provide novel resistance sources, candidate genes, and genomic resources that offer valuable tools for breeding rice with improved ShB resistance