Genetic and phenotypic variation in a subset of durum wheat cultivars suitable for association mapping

RONCALLO PABLO; BEAUFORT VALERIA; CAMARGO-ACOSTA EMILY; GARBUS INGRID; ECHENIQUE VIVIANA

Mexico DF

Workshop; 21st International Triticeae Mapping Initiative workshop; 2011

CIMMyT

We report here the evaluation of a subset of 47 durum wheat [T. turgidum subsp. durum (2n = 4x = 28)] cultivars from diverse origins (Argentina [28], Italy [13] and CIMMyT [6]) from a complete population of 154 materials suitable for association mapping studies. We analyzed these materials for yield, quality and morpho-physiological traits such as grain yield, thousand kernel weight, kernel width, kernel length, test weight, grain protein content, SDS test, flour color (L*a*b*), yellow pigment content, plant height, heading date and flowering date. Durum wheat cultivars were tested in three environments from Argentina (Barrow 2006, Cabildo 2007, Barrow 2007), using a randomized complete block design with three replications, in 3 m2 plots. Correlation analyses among traits and ANOVA for all the traits were performed. Genetic diversity and relationships among these materials were assessed using five primer combinations of amplified fragment length polymorphisms (AFLP). In addition, allelic variation at the phytoene synthase 1 gene (Psy-B1), involved in the biosynthesis of carotenoids pigments, was explored. We detected genotype x environment interaction in all phenotypic traits, with a strong genotype effect on SDS test and yellow pigment content. Thousand kernel weight showed a significant positive correlation with grain yield (r=0.53) and negative correlation with flowering date (r=-0.59), grain protein content (r=-0.55) and flour b*(r=-0.49). Three thousand and thirty five (335) loci were screened with AFLP yielding a total of 160 (47.8%) polymorphic bands. An average of 32 polymorphic loci (ranging from 17 to 55) per primer combination was obtained. Unique bands by origin (Argentina [9], Italy [2]) were detected and significant differences among variety groups from Italy and Argentina (PhiPT=0.226, p<0.01) and from CIMMyT and Argentina (PhiPT=0121, p<0.05) were found by AMOVA.  UPGMA cluster analysis, based on the simple matching coefficient, showed that CIMMyT materials clustered together, whereas Argentinean and Italian cultivars had different degrees of genetic relationships. At least two alleles at the Psy-B1 locus (Psy-B1a and Psy-B1b) were found in a preliminary analysis.