Biochemical properties of tetraploid maize grain

Tetraploid maize attracts breeders because of its large kernel and cob sizes, high nutrient content, and higher yield of herbage mass than diploid maize. Hence, it is important to study its biochemical composition and nutritional value in order to develop original source material for breeding. Accessions of tetraploid sweet corn from VIR’s genebank were used to analyze biochemical composition of the grain. The main task of the work was to identify differences among the accessions at the level of the metabolite spectra. A comparison of the values in the content of total sugars in kernels homozygous for the su2 gene did not reveal significant differences between diploid and tetraploid genotypes, while the fractions of sugars revealed some differences. Studies have shown that in diploid grains deviations from the reference for the total sugars content are -8.2 mg/100g, and in tetraploid ones, -2.9 mg/100g, although the overall ratio of dominant and recessive alleles (1AA:2AA) remains the same in both genotypes. Tetraploid sweet corn showed greater variability of the coefficient of variation (CV) in the grain protein content (CV = 6.80%), starch (CV = 8.27%) and oil (CV = 13.3%) compared with the diploid one. Potential donors of high protein, starch and oil contents in the kernel of tetraploid sweet corn were identified. A new cultivar of tetraploid sweet corn, ‘Baksanskaya Sakharnaya’, was developed, with a yield up to 16 t/ha of cobs in a marketable milky ripeness state and representing predominantly the double-cob type. This cultivar has high flavor qualities due to the fact that its kernels contain 16.3% of protein, 63.2% of starch, and 7.5% of oil. Moreover, the cultivar is resistant to biotic environmental factors. The tetraploid genome provides greater variability of the kernel’s biochemical composition and other economically valuable traits due to its greater genetic capacity, compared with the diploid genome. Development of new high-yielding hybrids of sweet corn based on VIR’s holdings will allow breeders to significantly broaden the genetic polymorphism and assortment of modern breeding achievements, and contribute to providing high-quality raw materials for food and canning industry.