Enhancing kernel oil and tailoring fatty acid composition by genomics-assisted selection for dgat1-2 and fatb genes in multi-nutrient-rich maize: new avenue for food, feed and bioenergy.

ABSTRACT

Enhancing maize kernel oil is vital for improving the bioavailability of fat-soluble vitamins. Here, we combined favourable alleles of dgat1-2 and fatb into parental lines of four multi-nutrient-rich maize hybrids (APTQH1, APTQH4, APTQH5 and APTQH7) using marker-assisted selection (MAS). Parental lines possessed favourable alleles of crtRB1, lcyE, vte4 and opaque2 genes. Gene-specific markers enabled successful foreground selection in BC1F1, BC2F1 and BC2F2, while background selection using genome-wide microsatellite markers (127-132) achieved 93% recurrent parent genome recovery. Resulting inbreds exhibited significantly higher oil (6.93%) and oleic acid (OA, 40.49%) and lower palmitic acid (PA, 14.23%) compared to original inbreds with elevated provitamin A (11.77 ppm), vitamin E (16.01 ppm), lysine (0.331%) and tryptophan (0.085%). Oil content significantly increased from 4.80% in original hybrids to 6.73% in reconstituted hybrids, making them high-oil maize hybrids. These hybrids displayed 35.70% increment in oil content and 51.56% increase in OA with 36.32% reduction in PA compared to original hybrids, while maintaining higher provitamin A (two-fold), vitamin E (nine-fold), lysine (two-fold) and tryptophan (two-fold) compared to normal hybrids. Lipid health indices showed improved atherogenicity, thrombogenicity, cholesterolaemic, oxidability, peroxidizability and nutritive values in MAS-derived genotypes over original versions. Besides, the MAS-derived inbreds and hybrids exhibited comparable grain yield and phenotypic characteristics to the original versions. The maize hybrids developed in the study possessed high-yielding ability with high kernel oil and OA, low PA, better fatty acid health and nutritional properties, higher multi-vitamins and balanced amino acids, which hold immense significance to address malnutrition and rising demand for oil sustainably in a fast-track manner.