Exploitation of natural variability in maize for β - carotene content using HPLC and gene specific markers

Vitamin A deficiency is a major world health problem, affecting up to 127 million pre-school children and 7 million pregnant women worldwide (West, 2003). Human selection for yellow endosperm has led to diversification of grain carotenoid content and composition. This variation has remained largely untapped in modern breeding programs that have focused nearly exclusively on yield gains. Maize displays considerable natural variation for carotenoid composition, including vitamin A precursors α-carotene, β-carotene, and β -cryptoxanthin. Sixty four maize inbred lines of India were grown and evaluated for whole kernel carotenoids and beta carotene content using high performance liquid chromatography (HPLC). The lines averaged 14 :g/g for total carotenoids (5.58 to 63.9 :g/g) and 1.69 :g/g for β -carotene (0.122 to 4.74 :g/g). High level of β - carotene was observed in UMI 946, UMI 176, UMI 79, UMI 34 and UMI 12 and these would be used in the breeding programs to enhance the β – carotene contents. Previous study showed four natural lcyE polymorphisms explained 58% of the variation in these two branches and a threefold difference in provitamin A compounds. In screening for polymorphisms in key haplotypes, four regions were selected and scored across the entire panel of favourable haplotype using SNP and SSR markers. The polymorphs were obtained for all primer used and the presence of the amplification of for particular marker showed the increase in β - carotene content across the inbreds. Development of LCYE based breeding markers for maize alone will not be effective unless hydroxylation is also controlled, for non pro vitamin A xanthophylls compounds will predominate. So in our future study, we should be aiming at breeding for high β - carotene in maize by emphasizing on characterization of β - carotene hydroxylase genes for enhancing the relative levels of seed β - carotene.