Marker-Assisted Breeding of Thermo-Sensitive Genic Male Sterile Line 1892S for Disease Resistance and Submergence Tolerance

Abstract: The development of hybrid rice has significant contribution in rice production and food security in China for over 40 years. Rice line 1892S is an elite thermo-sensitive genic male sterile (TGMS) rice line for two-line hybrid rice production. However, 1892S is susceptible to rice blast caused by Magnaporthe oryzae, bacterial blight caused by Xanthomonas oryzae pv. oryzae and submergence. The utilization of natural disease resistance and stress tolerance in rice breeding is the most efficient and economical way to combat or adapt to these biotic and abiotic stresses. Here we report the introduction of blast resistance (R) gene Pi9, bacterial blight R gene Xa21 and submergence tolerance gene Sub1A into 1892S genetic background through backcrossing and marker-assisted selection. The improved TGMS line 31892S and its hybrids conferred disease resistance to rice blast and bacterial blight and showed submergence tolerance for over 14 days without significant loss of viability. The sterility-fertility conversion of 31892S was similar to that of 1892S. 31892S and its derived hybrid rice had similar agronomic traits and grain quality to 1892S and the control hybrid rice, respectively. The newly developed 31892S provides an improved TGMS line for two-line hybrid rice production with disease resistance to rice blast and bacterial blight, submergence tolerance and no yield penalty or change in grain quality. Key words: rice; thermo-sensitive genic male sterility; bacterial blight; rice blast; disease resistance; submergence tolerance; marker-assisted selection