Genetic variability of tocopherol composition in sunflower seeds as a basis of breeding for improved oil quality

The variability of seed tocopherol content in wild sunflower species, the expressivity of tph1 and tph2 mutations in different lines and the oxidative stability of sunflower oil with altered tocopherol and fatty acid composition were objectives of this research. Near-isogenic lines for three genes, i.e. Tph1, Tph2, and Ol, were developed and investigated. Tocopherol content was determined with TLC and HPLC, as well as fatty acid composition with GC of methyl esters. Rancimat tests were used to estimate the oxidative stability of the oil. The seed tocopherol composition of wild sunflower species was shown to be uniform with a prevailing content of the alpha-homologue (90-99%). The genetic background of different near-isogenic lines was found to influence expressivity of mutations for tocopherol composition. High content of strong antioxidants, such as beta-, gamma-, and delta-tocopherols increased oil oxidative stability of linoleic and oleic types of oil by 1.2-3.0 times. The breeding model of sunflower hybrids should include antioxidant and vitamin parameters balanced for oils of different applications.