Improved sugar content in a sweet corn grain mutant with high quality protein and anthocyanin

Abstract

The kernels of red or purple sweet corn are rich in anthocyanin; however, increasing the tryptophan content in kernel via the opaque-2 gene would confer more nutritional value. The objective of this study was to increase the tryptophan content in the kernels of red sweet corn via conventional plant breeding. A simple sequence repeat marker, phi057, was used in marker assisted-selection (MAS) for the opaque-2 gene. In the S1 segregating population, opaque-2 plants were detected using MAS, phi057. Selected lines with good agronomic characters were self-pollinated until the S6 generation. Their tryptophan content in the protein was about 1% (one-quarter higher than for the non-opaque-2 checks), while the red kernel lines had total anthocyanin contents in the range 259–557 mg/100 g. The main anthocyanin component was pelargonidin-3-glucoside. The tryptophan content of F₁ hybrids was in the range 0.88–0.98% and their total anthocyanin contents were in the range 144–364 mg/100 g, much higher than for the check hybrid having tryptophan and anthocyanin contents of approximately 0.75% and 27 mg/100 g, respectively. The total sugars content in the F₁ hybrids was in the range 326–385 mg/g, which was the same level as in commercial hybrids. Therefore, the specific goal of a high sweetness level of triple grain mutants was achieved, and the fresh ear yield of the F1 hybrids was at the commercial standard. In summary, new commercial sweet corn varieties can be launched soon with excellent functional food quality with high tryptophan and anthocyanin contents in the kernel.