Genetic Mapping of Flavonoid Grain Pigments in Durum Wheat

Pigmented cereal grains with high levels of flavonoid compounds have attracted theattention of nutritional science backing the development of functional foods with claimed healthbenefits. In this study, we report results on the genetic factors controlling grain pigmentation indurum wheat using a segregant population of recombinant inbred lines (RILs) derived from a crossbetween an Ethiopian purple grain accession and an Italian amber grain cultivar. The RIL populationwas genotyped by the wheat 25K SNP array and phenotyped for total anthocyanin content (TAC),grain color, and the L*, a*, and b* color index of wholemeal flour, based on four field trials. Themapping population showed a wide variation for the five traits in the different environments, asignificant genotype x environment interaction, and high heritability. A total of 5942 SNP markerswere used for constructing the genetic linkage map, with an SNP density ranging from 1.4 to2.9 markers/cM. Two quantitative trait loci (QTL) were identified for TAC mapping on chromosomearms 2AL and 7BS in the same genomic regions of two detected QTL for purple grain. The interaction between the two QTL was indicative of an inheritance pattern of two loci having complementary effects. Moreover, two QTL for red grain color were detected on chromosome arms 3AL and 3BL. The projection of the four QTL genomic regions on the durum wheat Svevo reference genome disclosed the occurrence of the candidate genes Pp-A3, Pp-B1, R-A1, and R-B1 involved in flavonoid biosynthetic pathways and encoding of transcription factors bHLH (Myc-1) and MYB (Mpc1, Myb10), previously reported in common wheat. The present study provides a set of molecular markers associated with grain pigments useful for the selection of essential alleles for flavonoid synthesis in durum wheat breeding programs and enhancement of the health-promoting quality of derived foods.