Expression analysis of β-carotene hydroxylase1 and opaque2 genes governing accumulation of provitamin-A, lysine and tryptophan during kernel development in biofortified sweet corn

• Published in: 3 Biotech Vol. 11; no. 7; p. 325
• Main Authors: Mehta, Brijesh Kumar, Chhabra, Rashmi, Muthusamy, Vignesh, Zunjare, Rajkumar Uttamrao, Baveja, Aanchal, Chauhan, Hema Singh, Prakash, Nitish Ranjan, Chalam, Vasimalla Celia, Singh, Ashok Kumar, Hossain, Firoz
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-07-2021; Springer Nature B.V
• Subjects: Accumulation; Agriculture; Bioinformatics; Biomaterials; Biotechnology; Cancer Research; Carotene; Chemistry; Chemistry and Materials Science; Gene regulation; Genes; Kernels; Lysine; Marker-assisted selection; Nutrients; Original; Original Article; Pattern analysis; Pollination; Stem Cells; Sweetcorn; Transcription; Tryptophan; β-Carotene; Gene expression; Sweet corn
• ISSN: 2190-572X; 2190-5738
• DOI: 10.1007/s13205-021-02837-1

Traditional sweet corn possesses low levels of provitamin-A (proA), lysine and tryptophan. Mutant version of
β-carotene hydroxylase1
(
crtRB1
) gene affecting the accumulation of β-carotene (BC), β-cryptoxanthin (BCX) and proA, and
opaque2
(
o2
) gene governing the enhancement of lysine and tryptophan were introgressed together into elite sweet corn inbreds through marker-assisted selection. Here, we analyzed the expression pattern of
crtRB1
and
o2
genes among introgressed and traditional sweet corn inbreds at 20-, 24- and 28-days after pollination (DAP). The introgressed inbreds possessed two- to sevenfolds higher BC, BCX, proA, lysine and tryptophan compared to their original inbreds. However, all the nutrients attained the peak at 20-DAP (BC: 9.95 µg/g, BCX: 8.21 µg/g, proA: 14.05 µg/g, lysine: 0.301%, tryptophan: 0.074%), which gradually reduced through 24-DAP (BC: 8.24 µg/g, BCX: 7.53 µg/g, proA: 12.01 µg/g, lysine: 0.273%, tryptophan: 0.057%) and 28-DAP (BC: 5.84 µg/g, BCX: 5.82 µg/g, proA: 8.75 µg/g, lysine: 0.202%, tryptophan: 0.037%). Biofortified sweet corn inbreds possessed significantly lower expression levels of
crtRB1
(4.1-fold) and
o2
(2.2-fold) compared to their wild type alleles in traditional sweet corn inbreds across DAPs. The expression of
crtRB1
and
o2
increased from 20-DAP to attain the highest peak at 24-DAP, and further decreased by 28-DAP. The transcript levels of
crtRB1
were negatively correlated with BC (
r
 = − 0.83), BCX (
r
 = − 0.79) and proA (
r
 = − 0.83) across dates of harvest. Lysine (
r
 = − 0.83) and tryptophan (
r
 = − 0.73) were also inversely associated with
o2
transcript levels. This is the first report on expression of
crtRB1
and
o2
genes during kernel development in biofortified sweet corn. This information holds immense promise in understanding the dynamics of gene-regulation during kernel development in sweet corn.