Through constructing the F-2 clonal population of an intercross,Teqing/Lemont,two quantitative trait loci(QTLs),qSB-9 and qSB-11,contributing to sheath blight resistance were preliminarily detected.Furthermore,from the F-2 clonal population of Teqing/Lemont,a double-susceptible and two double-resistant clonal lines was selected as pure parents and were separately intercrossed and backcrossed to recurrent parents,Teqing and Lemont.In BC-1F-1,marker-assisted selection was conducted and all backcrossed plants were inoculated by short toothpicks incubated with a strain,RH-9 of Rhizoctonia solani for identification of the resistance.In BC-2F-1,according to the similarity of integrative traits between backcrossed plants and their recurrent parents,we gathered BC-2F-2 seeds of some backcrosses.BC-2F-2 plants of coinciding requirement were selected through marker-assisted selection during the period of seedling stage,and separately mixed as homozygous lines.Thus,double-susceptible lines in the background of Teqing,double-susceptible and double-resistant lines in the background of Lemont were developed.The results of the inoculation test suggested that method of molecular marker-assisted selection for sheath blight resistance with investigation of disease ratings in backcross generations can quickly check up the reliability of location of resistant QTL and confirm the QTL interval on chromosome.
