Breeding Novel Short Grain Rice for Tropical Region to Combine Important Agronomical Traits, Biotic Stress Resistance and Cooking Quality in Koshihikari Background

Breeding program strategies to develop novel short grain white rice varieties such as japonica (short grain) that introgress biotic stress resistance and high grain quality have been developed using indica rice (Pin Kaset + 4 and Riceberry) for applications in japonica rice (Koshihikari) improvement. Four breeding lines showing promising agronomic performance with short grain and low amylose content (< 20%) were obtained. In addition, sensory testing of these breeding lines showed high scores that similar to Koshihikari. Two promising lines, KP48-1-5 and KP48-1-9, which possessed a combination of four genes resistance to different biotic stresses (Bph3 + TPS + Xa21 + Pi-ta) and four genes for grain quality (GS3 + SSIIa + wxb + badh2), were developed using marker-assisted selection (MAS) with the pedigree method. The current study clearly illustrated the successful use of MAS in combining resistance to multiple biotic stresses while maintaining a high yield potential and preferred grain quality. Moreover, the results indicated that this breeding program, which includes crossing temperate japonica with indica, can create novel short grain rice varieties adapted to a tropical environment, like the japonica type.