Understanding the Genetic Basis of Carotenoid Concentration in Lentil (Lens culinaris Medik.) Seeds
Lentils are an inexpensive source of protein, vitamins and minerals. Lentil seeds contain carotenoids that have antioxidant properties and play an important nutritional role as precursors of vitamin A. Improving concentration of carotenoids in lentils has potential as component of a bio-fortification program. The understanding of the genetic control of carotenoids in lentil will help breeders develop strategies for developing varieties with higher carotenoid concentration. The objectives of this research program were to evaluate the concentration of carotenoids in mature lentil seeds and to identify genomic regions that possibly influence carotenoid concentration. The experimental program involved: i) analyzing the carotenoid concentration in seeds produced from the specific crosses among lentil genotypes with three cotyledon colours using high pressure liquid chromatography (HPLC) ii) analyzing an association mapping panel to develop potential single nucleotide polymorphism (SNP) markers for genes associated with carotenoid concentration For the first objective, dihybrid crosses were made between lentil cultivars with red, yellow and green cotyledons. Hybridized lentil populations were grown in the greenhouse and phytotron chamber up to the F3 generation and then seeds were analyzed for carotenoid concentration. As expected, the expression of red cotyledon colour was dominant over yellow, and these two cotyledon colours were inhibited by an epistatic interaction with green cotyledon colour. Lentil seeds with green cotyledon colour had higher carotenoid concentration than red cotyledon types which in turn had higher carotenoid concentration compared to yellow cotyledon lentils. Identifying molecular markers associated with carotenoids can be part of a crop improvement strategy for both marker-assisted selection and marker-assisted breeding (MAS; MAB). Association mapping using broad genetic materials might result in high resolution. For this purpose an association mapping panel of 143 lentil genotypes was grown at two different locations near Saskatoon, Canada, in 2011 and 2012. Concentration of three carotenoids in lentil seed samples was measured using reverse phase HPLC. Of the 143 genotypes, 60 accessions were common for both years and locations. Concentrations of lutein, zeaxanthin and violaxanthin in seed samples were determined. Genotyping was accomplished using 1536 SNP (single nucleotide polymorphism) markers of an Illumina Golden-Gate assay. It was determined that 168 of the SNP markers were significantly associated with carotenoid concentration components using the GLM (generalized linear model) model. These putative SNPs could be used for MAS and MAB to improve selection for carotenoids in lentil to increase the nutritional value of lentil.
HPLC, GLM, SNP,
Master of Science (M.Sc.)