Development of sunflower germplasm with high delta-tocopherol content

Abstract

Tocopherols are the main compounds with antioxidant activity in oilseeds Sunflower seeds contain predominantly alpha-tocopherol, which accounts for more than 90% of the total tocopherols in the seeds. This tocopherol derivative possesses a maximum vitamin E or in vivo antioxidant activity, but it exerts a minimum in vitro protective action in oils and food containing them. Other tocopherol derivatives such as beta-, gamma-, and delta-tocopherol are more powerful antioxidants than alpha-tocopherol. Accordingly, a partial replacement of alpha-tocopherol in sunflower seeds is an important breeding objective. So far, variants with high gamma tocopherol content (>85%), medium beta-tocopherol content (30% to 50%), and medium delta-tocopherol content (<25%) have been developed. The objective of the present research was to develop sunflower germplasm with novel tocopherol profiles. Seed of four Peredovik accessions of different origins were used for chemical mutagenesis with ethyl methane sulfonate (EMS). Single-seed screening in the M2 generation resulted in the identification of an M2 seed with 19% gamma-tocopherol. M3 seeds exhibited wide segregation for gamma-tocopherol content, from zero to about 85%. Such a wide segregation has not been observed in previously developed high gamma-tocopherol germplasms which segregate for low and high but not for intermediate levels of gamma-tocopherol. Selection for high gamma-tocopherol content within this mutant produced an M4:5 line with stable high concentration of gamma-tocopherol, above 90% of the total tocopherols. The line was designated IAST-1. Crosses between IAST-1 and the line T589, with medium beta-tocopherol content, produced segregants with increased levels of up to 68% delta-tocopherol.