Analysing genetic control of cooked grain traits and gelatinization temperature in a double haploid population of rice by quantitative trait loci mapping

Cooking quality in rice grains is a complex trait which requires improvement. Earlier reports show varying genetic influence on these traits, except for a common agreement on waxy (Wx) and alkali degeneration (Alk) loci on chromosome 6. The present study involved 86 doubled haploid lines derived from an indica x japonica cross involving IR64 and Azucena. Grain parameters viz., raw grain length (RGL), raw grain breadth (RGB), cooked grain length (CGL), cooked grain breadth (CGB), gelatinization temperature (GT), grain shape (RGS), length elongation ratio (LER) and breadth expansion ratio (BER) were subjected to mixed model mapping of quantitative trait loci (QTL). Segregation data of 175 markers covering a distance of 2395.5 cM spanning the entire genome were used. Fifteen main effect QTLs were detected spread over the genome, except on chromosomes 4, 8 and 11. Thirty epistatic interactions significantly influencing the traits were detected. Twelve of the main effect QTLs were involved in epistatic interactions. One main effect QTL associated with LER was detected near Alk locus. QTLs located for grain length on chromosomes 9 and 10 are reported for the first time. Detection of many epistatic loci and involvement of main effect QTLs in interactions demand for judicious selection of QTLs in marker-assisted selection programmes.