Marker-assisted introgression of rare allele of -carotene hydroxylase (crtRB1) gene into elite quality protein maize inbred for combining high lysine, tryptophan and provitamin A in maize

Vitamin A deficiency in humans is a widespread health problem. Quality protein maize (QPM) is a popular food rich in lysine and tryptophan, but poor in provitamin A (proA). Here, we report the improvement of an elite QPM inbred, HKI1128Q for proA using marker-assisted introgression of crtRB1-favourable allele. HKI1128 was one of the parental lines of three popular hybrids in India and was converted to QPM in our earlier programme. Severe segregation distortion for crtRB1 was observed in BC1F1, BC2F1 and BC2F2. Background selection by 100 SSRs revealed mean recovery of 91.07% recurrent parent genome varying from 88.78% to 93.88%. Across years, introgressed progenies possessed higher mean -carotene (BC: 9.22 mu g/g), -cryptoxanthin (BCX: 3.05 mu g/g) and provitamin A (proA: 10.75 mu g/g) compared to HKI1128Q (BC: 2.26 mu g/g, BCX: 2.26 mu g/g and proA: 3.38 mu g/g). High concentration of essential amino acids, viz. lysine (mean: 0.303%) and tryptophan (0.080%) in endosperm, was also retained. Multi-year evaluation showed that introgressed progenies possessed similar grain yield (1,759-1,879kg/ha) with HKI1128Q (1,778kg/ha). Introgressed progenies with higher lysine, tryptophan and proA hold immense potential as donors and parents in developing biofortified hybrids.