Effects of Recurrent Parents and Introduced Xa1, Xa2 and Xa3 Genes on Rice Grain Quality

With 3 different recurrent parents (RPs) (‘Suwon 345’, ‘Iri 390’ and ‘Milyang 95’) and 3 different donor parents (‘Daecheongbyeo’, ‘RantaiEmas’ and ‘Chugoku 69’ for Xa1, Xa2 and Xa3, respectively), 9 near isogenic lines (NILs) were developed and subjected to the analysis of grain qualities and physicochemical properties including milling characteristics and patterns for amylogram and texture to investigate the effects of introduced Xa1, Xa2 and Xa3 genes compared with each RP variety. Significant effects of RPs (A), NILs (B) and their interaction (A×B) were found on the grain appearance (grain length, grain width, grain thickness and length/width ratio), milling ratio, 1000-grain weight, protein and fatty acid contents, peak, hot and cool viscosities and Toyo taste meter values. Brown/rough rice ratio, perfect kernel of milled rice, amylose content, consistency and setback values revealed marked RP variation. Alkali spreading value showed significant effects on the RPs and NILs. Mg/K ratio revealed marked RPs and RPs×NILs interaction variation. On the other hand, milled/brown rice ratio and the gelatinization temperature (GT) showed no significance on the RPs, NILs and RPs×NILs interaction. RPs greatly influenced the determination of grain quality, milling characteristics, cooking and eating qualities of NILs. Therefore, the choice of RPs plays a critical role in backcross breeding programs. On the other hand, it is assumed that Xa1, Xa2 and Xa3 genes have not negative effect for the characteristics associated with grain qualities and taste of cooked rice.