Genetic variability for kernel beta -carotene and utilization of crtRB1 3'TE gene for biofortification in maize (Zea mays L.)

Carotenoids are the major sources of dietary precursor of vitamin A and act as potential antioxidant besides preventing diseases such as night blindness in humans. Vitamin A deficiency is a global problem, but is particularly prevalent in developing countries like India, where 31 percent of pre-school children are reportedly affected. Evaluation of genetic variability for kernel beta -carotene in 105 maize inbreds of diverse pedigree from India- and CIMMYT- origin revealed significant variation ranging from 0.02 to 16.50 ueg/g. One of the key reasons for wide variation of kernel beta -carotene is due to the allelic variation at crtRB1 3'TE gene. Five among 95 inbreds possessed the favourable crtRB1 3'TE allele with a mean beta -carotene concentration of 0.86 ueg/g. In contrast, the same allele detected in 20 CIMMYT-Maize HarvestPlus genotypes contributed a mean kernel beta -carotene concentration of 11.29 ueg/g. The contrast in beta -carotene concentration in Indian and CIMMYT genotypes could be attributed to the presence of SNPs and InDels in crtRB1 3'TE locus, along with the presence/absence of favourable alleles of other important genes influencing the carotenoid biosynthetic pathway. Marker-assisted breeding has been initiated, to introgress the crtRB1 3'TE favourable allele using high beta -carotene CIMMYT inbreds as donors, to develop provitamin A-rich maize cultivars suitable for maize growing regions in India.