Development of Introgression Lines and Identification of QTLs for Resistance to Sheath Blight

Abstract

In this study,two random BC2F2 populations were developed by cross and backcross,in which two major hybrid restorer lines Shuhui 527 and Minghui 86 were used as recurrent parents respectively,and Jiangxisimiao used as donor.The bulks of the BC2F2 populations were inoculated with Rhizoctonia solani to screen the lines resistant to sheath blight,and 49 resistant introgression lines(ILs) were selected.The genotypes of ILs were analyzed with evenly distributed polymorphic SSR markers,and a total of 12 significant loci were identified by χ2 test analysis.Among them,two allelic frequency-deviation loci were located in the same or near regions identified in the previous studies.In the field test without artificial inoculation,there was no significant difference between all the agronomic traits investigated in the selected ILs and their recurrent parents.Under heavily diseased conditions,six ILs with Shuhui 527 background and two ILs with Minghui 86 background showed similar agronomic traits and significantly higher resistance to sheath blight than their recurrent parents at two experimental sites,which can be served as immediate sources of sheath blight resistance for hybrid rice breeding and directly used in hybrid rice production.