Survey Of Carotenoid and Tocopherol Variability in Corn

Recent investigations into carotenoid and tocopherol activity indicate that these antioxidants are associated with the prevention of cancer and cardiovascular disease. Both carotenoids and tocopherols can be found in corn. A replicated survey of 21 sweet and dent corn inbreds was conducted to determine qualitative and quantitative variability of carotenoid and tocopherol content and form in corn germplasm. Ears were harvested at 20 days after pollination (DAP) and frozen in liquid nitrogen to remove kernels. Lyophilized samples were extracted, then analyzed using a reverse-phase HPLC method developed in this laboratory to simultaneously identify and quantify the carotenoids: lutein, zeaxanthin, β-cryptoxanthin, α-carotene, and β-carotene, as well as the α-, δ- and γ- forms of tocopherol. The primary carotenoids in immature corn were found to be lutein, and zeaxanthin, with the γ form of tocopherol dominating. Mean values among the genotypes were observed to range from 0.6 to 20 and 9 to 30 mg/g dry weight for lutein and γ-tocopherol, respectively, suggesting variability among inbreds in genes regulating the metabolism of these compounds. From this data, parents have been chosen for the creation of two segregating F2:3 populations, which will be used to study genetic associations of these compounds. This survey also found significant variability in antioxidant compounds between IL731a and W6786 for which a saturated linkage map containing 94 probes has already been constructed. Genetic investigations of this population will be conducted in the near future. The observed genetic variability suggests the possibility of developing germplasm with enhanced levels of these chemoprotectant compounds.