THE CAROTENOID BIOSYNTHETIC AND CATABOLIC GENES IN WHEAT AND ASSOCIATION WITH YELLOW PIGMENTS

In plants, carotenoids play an important role in the photosynthetic process and photooxidative protection, and represent the substrate for the synthesis of abscisic acid and strigolactones. In addition to their protective role as antioxidant and precursors of essential vitamin A, in wheat carotenoids are important as they confer whiteness and yellowness degree to end-finished products. Understanding the genetic basis of yellow pigments and the identification of associated markers provides the basis for improving wheat quality by molecular breeding. Twenty-four candidate genes involved in the biosynthesis and catabolism of carotenoid compounds have been identified in wheat by comparative genomics. Single nucleotide polimorphisms (SNP) found in the coding sequences of 19 candidate genes allowed determining the chromosomal location and the accurate map position on two reference consensus maps. The genome-wide association study based on genotyping a tetraploid wheat collection with 81,587 gene-associated SNPs validated quantitative trait loci (QTLs) previously detected in biparental populations and discovered new QTLs for colour-related traits. Ten carotenoid genes mapped in corresponding chromosome regions with QTLs indicating possible relations between candidate genes and yellow pigments. The availability of markers within the coding sequences of candidate genes can allow to elucidating the mechanism of carotenoid accumulation in the wheat kernels and to exploiting the genetic variability of colour-related traits for the nutritional and commercial improvement of end-finished products.