Selection for contrasting seed tocopherol content in sunflower seeds

Sunflower oil, with more than 0·9 of tocopherols in the alpha-tocopherol form, supplies more vitamin E than any other vegetable oil. Thus far, no breeding to increase vitamin E levels in sunflower seeds has been conducted. The objective of the present research was to develop sunflower lines with high and low total seed tocopherol content through evaluation and subsequent selection of a large germplasm collection (952 sunflower entries). A range of variation from 119 to 491 mg/kg was found. Selection conducted from S1 to S4 plant generations allowed the isolation of line IAST-413, with an increased tocopherol content of 467 mg/kg compared to 251 mg/kg in the control line HA89, and line IAST-522, with a reduced tocopherol content of 73 mg/kg. Another accession with potentially high tocopherol content, but completely self-incompatible, was crossed to the line HA89 followed by plant-to-row selection up to the F5 plant generation; it averaged 463 mg/kg compared to 240 mg/kg in HA89. Two field experiments carried out at Córdoba in southern Spain in 2006 and 2007 with different sowing dates confirmed that the increased tocopherol content in the selected lines was consistently expressed across environments.