Development of multinutrient-rich biofortified sweet corn hybrids through genomics-assisted selection of shrunken2, opaque2, lcyE and crtRB1 genes.

Sweet corn has gained worldwide popularity. Traditional sweet corn possesses low concentration of essential nutrients such as lysine (0.15-0.25%), tryptophan (0.03-0.04%) and provitamin-A (proA 3-4 ppm), and deficiency leads to serious health problems in humans. Here, stacking of shrunken2 (sh2), opaque2 (o2), lycopene epsilon cyclase (lcyE) and β-carotene hydroxylase (crtRB1) genes  were undertaken in the parents of four hybrids viz., APQH1, APHQ4, APHQ5 and APHQ7 using marker-assisted backcross breeding (MABB). Gene-linked markers (umc2276 and umc1320) for sh2, while gene-based markers for o2 (umc1066 and phi057), lcyE (5'TE-InDel) and crtRB1 (3'TE-InDel), were used for genotyping in BC1F1, BC2F1 and BC2F2. Selected backcross progenies showed high recovery of recurrent parent genome (92.4-97.7%). The reconstituted sweet corn hybrids possessed significantly high lysine (0.390%), tryptophan (0.082%) and proA (21.14 ppm), coupled with high kernel sweetness (brix 18.96%). The improved sweet corn hybrids had high cob yield (12.22-15.33 t/ha) across three environments. These newly developed biofortified sweet corn hybrids possess great significance in providing balanced nutrition. This is the first report of combining sh2, o2, lcyE and crtRB1 genes for enrichment of sweet corn hybrids with multiple essential nutrients.