Comparison and Confirmation of Quantitative Trait Loci Conferring Partial Resistance to Rice Sheath Blight on Chromosome 9

Abstract Sheath blight (SB), caused by Rhizoctonia solani, is one of the worst rice (Orzya sativa) diseases worldwide. Resistance to the SB disease in rice is a complex trait controlled by quantitative trait loci (QTLs). Through map integration, we found several previously identified SB resistance (SBR) QTLs reported in inconsistent regions on the long arm of chromosome 9. Five of them were detected on ‘Jasmine 85’ (J85), ‘Minghui 63’ (MH63), and ‘Lemont’ (LMNT) rice and were designated qSB-9J85-1, qSB-9J85-2, qSB-9MH63-1, qSB-9MH63-2, and qSB-9LMNT, respectively, in the present study. To further verify and physically map the five potential SBR QTLs, we introduced these SBR QTLs into a common susceptible variety (LMNT) and developed a few chromosomal segment substitution lines through marker-assisted selection. After artificial inoculation with the SB fungus, we were able to validate qSB-9J85-2 but not the other four SBR QTLs; whereas, on MH63, an SBR QTL designated qSB-9MH63-3 was confirmed in the region...