Selection for contrasting seed tocopherol content in sunflower seeds

Abstract

SU MMARYSunflower 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 S 1 to S 4 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 F 5 plant generation; it averaged 463 mg/kg compared to 240 mg/kg in HA89. Two field experiments carried out at Co´rdoba 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. INTRODUCTIONVitamin E is a family of fat-soluble antioxidants that protect cellular membrane lipids against oxidative damage, which has been associated with a decreased risk of developing some forms of cancer, cardiovascular diseases and degenerative processes linked to disease (Packer & Obermu¨ller-Jevic 2002). The main naturally occurring compounds with vitamin E activity are tocopherols and tocotrienols. Tocopherols occur ubiquitously in plant tissues, with the highest concentrations being found in seeds. There are four tocopherols, alpha-, beta-, gamma-and delta-tocopherol, which differ in their vitamin E activities. Alpha-tocopherol exerts the highest vitamin E activity in animals (Pongracz et al. 1995). There is a large body of medical evidence pointing to the benefits for human health associated with daily, moderate, vitamin E supplementation (Bramley et al. 2000).Gamma-tocopherol, with only one-tenth the vitamin-E activity of alpha-tocopherol (Pongracz et al. 1995), is the predominant tocopherol derivative in most oilseeds (Padley et al. 1994). Sunflower, with more than 0 . 9 of tocopherols in the alpha-tocopherol form, represents a remarkable exception. The high vitamin E content of sunflower oil is being used by some manufacturers as a claim to attract consumers, even through fortification of the oil with either natural or synthetic alpha-tocopherol. Several brands of sunflower oil fortified with alpha-tocopherol are currently being marketed in Spain. Sunflower cultivars with increased concentrations of alpha-tocopherol in the seeds would produce oils with naturally enhanced vitamin E value.The tocopherol content in the extracted seed oil is the result of several factors, the most important being the tocopherol content in the seeds, the oil content in the seeds, the oil extraction system and t...

Alpha-tocopherol and gamma-tocopherol concentration in vegetable oils

“…This information regarding the sunflower oil is in accordance with the statement that this compound is found in higher concentrations in wheat germ oils, olive oil and sunflower oil (Traber, 2006;Gliszczyńska-Świgło et al, 2007;Smolarek & Suh, 2011;Velasco et al, 2010).…”

Tocopherols and phytosterols in sunflower seeds for the human food market

“…These tocopherol levels are within the range of variation reported in a large germplasm collection of sunflower, from 119 to 491 mg kg -1 seed kernel (Velasco et al, 2010). α-tocopherol was in all cases the predominant tocopherol form accounting in all cases for more than 96% of the total tocopherols, which is the typical tocopherol profile in sunflower except for breeding material in which alternative tocopherol profiles have been developed (Fernández-Martínez et al, 2009).…”

Expression of modified tocopherol content and profile in sunflower tissues

“…The lines IAST‐4 and TS‐1 with different increased levels of gamma‐ and delta‐tocopherol in seeds and the line IAST‐5 with high beta‐tocopherol content in seeds were isolated from crosses between the lines IAST‐1 and T589 8. The line IAST‐522 with reduced total seed tocopherol content was isolated from an accession of the germplasm collection of IAS‐CSIC 19. The lines IAST‐413 and IAST‐306 with increased total seed tocopherol content were developed by pedigree selection from accessions of the germplasm collections of the IAS‐CSIC and the NPGS‐USDA respectively 19.…”