Expressivity of tocopherol mutations in sunflower

Abstract

SUMMARY Influences of genetic background, ontogenesis and environment on tocopherol mutations in sunflower were estimated in this study. The content of α/βtocopherols varied from 40/60 to 60/40% in seeds of different inbred lines containing the tph1 gene. The lines containing the tph2 gene ranged widely in α/γtocopherols, from 0/100 to 80/20%. A double mutation showed variability in different inbred lines in α/β/γ/δ-tocopherol contents from maximum expressivity of 0/0/60/40 to minimum 40/25/25/10%, due to incomplete expressivity of tph2. Seed maturation from 10 to 38 DAF influenced tocopherol composition in both normal and mutant genotypes by increasing the α-tocopherol content. The content varied from 81 to 97% in a normal genotype, from 33 to 50% in tph1 mutation and from 0 to 6% in tph2 mutation. Tocopherol mutations were shown to express their phenotype in different parts of a plant. All roots, hypocotyls, leaves, pollen and callus from the seeds, hypocotyls and leaves had normal, tph1, tph2 and double mutation tocopherol profiles depending on the genotype. The only exception was the absence of tph1 expressivity in the green tissue of the leaves. The experiment with day/night temperatures varying during seed development from 20/18 to 30/26°C showed an increased α-tocopherol content from 39 to 48% in tph1 mutation. Both a normal genotype (about 97% of α-tocopherol) and tph2 mutation (about 98% of γ-tocopherol) were constant in these two temperature regimes. Genetic background was the main factor that influenced the expressivity of tph2 in sunflower.