Analysis of lycopene variation and genetic characteristics in wheat grain

Lycopene is a kind of carotenoid with strong antioxidant capacity and a target molecule for wheat lycopene biofortification. This study employed high performance liquid chromatography (HPLC) to measure the lycopene content of wheat grains from a Chinese mini-core collection (MCC) wheat containing 262 accessions that were grown in three environments. A genome-wide association study (GWAS) of a 90K SNP array identified the genetic loci associated with lycopene content. The mean lycopene content of wheat grain was measured at 0.223 ± 0.091 μg/g, exhibiting significant variation (CV = 36.39%-49.23%), with a heritability estimate of 85.6%. A total of 12 accessions contained high lycopene contents (> 0.4 ± 0.078 μg/g), which is potentially useful for wheat lycopene biofortification. The lycopene in MCC grains was not correlated with geographical location, grain color, winter/spring variety, accession type, and folate content of wheat. In comparison, lycopene content was significantly and positively correlated with lutein and maturity date, as well as negatively correlated with grain width and thousand-kernel weight. GWAS identified a total of 12 stable genetic loci, among which QLyc.sxau-2B, QLyc.sxau-7A.2 and QLyc.sxau-7B had relatively greater effects on lycopene in wheat grains. Six stable QTL had additive effects (44.72%-149.14%). The functional regions of five QTL, QLyc.sxau-1A, QLyc.sxau-5A.2, QLyc.sxau-5B, QLyc.sxau-7A.2 and QLyc.sxau-7B, contain regulatory genes involved in the known pathway of lycopene metabolism. Six candidate genes (TraesCS1A02G206900, TraesCS5A02G494200, TraesCS5B02G529400, TraesCS7A02G557300, TraesCS7B02G482000 and TraesCS7B02G419000) were preliminary selected in functional regions of five QTL. Genotype emerged as the primary factor influencing lycopene variation among wheat varieties. A total of 12 stable QTL associated with lycopene was identified, among which six stable QTL had additive effects. These findings provide a theoretical basis for further genetic analysis and the development of molecular breeding strategies aimed at increasing lycopene content through the accumulation of favorable alleles.