QTLs Associated to Color in a RILs Mapping Population of DurumWheat

RONCALLO PABLO; GERARDO CERVIGNI; CARRERA ALICIA; AKKIRAJU PAVAN CHAND; GOMEZ PATRICIA; MIRANDA RUBEN; SEGHEZZO MARIA LAURA; MOLFESE ELENA; WEHRHAHNE LILIANA; JENSEN CARLOS; BARIFFI JOSE H.; HELGUERA MARCELO; ECHENIQUE VIVIANA

Bologna, Italia

Simposio; International Symposium From Seed To Pasta: The Durum Wheat Chain. Multidisciplinary approaches for a more sustainable and high-quality durum production?; 2008

Societa Produttori Sementi Bologna, CIMMyT, ICARDA

Color is one of the most important quality traits in durum wheat breeding programs. Specific desirable characteristics of grain color and semolina vary according to the final product and market requirements. Bright yellow color of grain and pasta products is affected by the carotenoid pigment content and their oxidative degradation, mainly due to lipoxygenase activity. The aims of this study were: i) to map QTLs (Quantitative Trait Loci) associated to grain carotenoid content and yellow color (b* value) in durum wheat ii) to estimate genetic parameters and the genotype-environment interactions related to this traits. A mapping population of 93 recombinant inbred lines (RIL) derived from the cross between the variety Kofa (high color) and the UC1113 line (intermediate color) was evaluated during the year 2006 in three environments of Argentina (Cabildo, Barrow and Balcarce). Whole meal samples were analyzed for carotenoid pigment content using a microtest and yellow color (Minolta). The experimental design was a randomized complete block with three replicates. Experimental plots were 3.0 m2 in size. The QTLs were mapped by environment on a genetic map of 210 molecular markers. The content of carotenoids and b* values were highly correlated in Cabildo (r = 0.86, P<0.001), Barrow (r = 0.85, P<0.001) and Balcarce (r = 0.86, P<0.001). The carotenoid pigment content ranged from 3.23 to 9.66 ppm and the yellow index (b* value) from 12.31 to 19.54. The ANOVA indicated that the effect of genotype, the environment and genotype x environment interaction were highly significant. The narrow sense heritability was very high for the carotenoid pigment content, being 97.0% in Cabildo, 97.15 % in Barrow and 97.88% in Balcarce. The corresponding values for b* value were 94.99 % in Cabildo, 95.44 % in Barrow and 95.05 % in Balcarce. These variables showed a bidirectional transgressive segregation in all the environments. Six QTLs  for b* value were identified, four of them with major effect (R2>10%).Three QTLs were mapped in Barrow on chromosomes 6A (LOD=6.94; R²=20.02), 7A (LOD=4.09; R²=11.34) and 7B (LOD=3.67; R²=9.88) and three QTLs in Balcarce 6A (LOD=9.93; R²=27.35), 7A (LOD=3.05; R²=7.00) and 7B (LOD=4.22; R²=10.76). QTLs for b* value were not found in Cabildo. Nine QTLs associated to carotenoid pigment were mapped, five with major effect. We found three QTLs in Cabildo on chromosomes 1B (LOD=3.02; R²=12.06), 5B (LOD=2.85; R²=9.60) and 6A (LOD=3.24; R²=11.74), three QTLs in Barrow 6A ( LOD=5.62; R²=16.28), 7A (LOD=3.62; R²=9.89) and 7B (LOD=3.12; R²=9.01) and three in Balcarce 6A (LOD=7.08; R²=20.42), 7A (LOD=2.86; R²=7.02) and 7B (LOD=2.70; R²=11.46). These results predict high genetic gains after phenotypic selection. Moreover, the markers flanking the QTL constitute useful tools for assisted selection, especially for the 6A QTL, which explains most of the phenotypic variance and was detected in all the environments considered.