Genetic possibilities for altering sunflower oil quality to obtain novel oils

Authors: Jocić, Siniša; Sakač, Zvonimir; Lečić, Nada; Škorić, Dragan

Source: Canadian Journal of Physiology and Pharmacology, Volume 86, Number 4, April 2008 , pp. 215-221(7)

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Abstract:

The sunflower is one of the four most important oilseed crops in the world, and the nutritional quality of its edible oil ranks among the best vegetable oils in cultivation. Typically up to 90% of the fatty acids in conventional sunflower oil are unsaturated, namely oleic (C 18:1, 16%-19%) and linoleic (C 18:2, 68%-72%) fatty acids. Palmitic (C 16:0, 6%), stearic (C 18:0, 5%), and minor amounts of myristic (C 14:0), myristoleic (C 14:1), palmitoleic (C 16:1), arachidic (C 20:0), behenic (C 22:0), and other fatty acids account for the remaining 10%. Advances in modern genetics, most importantly induced mutations, have altered the fatty acid composition of sunflower oil to a significant extent. Treating sunflower seeds with γ- and X-rays has produced mutants with 25%-30% palmitic acid. Sunflower seed treatment with X-rays has also resulted in mutants having 30% palmitoleic acid, while treatments with mutagenic sodium azide have produced seeds containing 35% stearic acid. The most important mutations have been obtained by treatment with dimethyl sulfate, which produced genotypes with more than 90% oleic acid. Mutants have also been obtained that have a high linoleic acid content (>80%) by treating seeds with X-rays and ethyl methanesulfonate. Of the vitamin E family of compounds, sunflower oil is known to predominantly contain α-tocopherol (>90%). Spontaneous mutations controlled by recessive genes have been discovered that significantly alter tocopherol forms and levels. The genes in question are tph₁ (50% α- and 50% β-tocopherol), tph₂ (0%-5% α- and 95%-100% γ-tocopherol), and tph₁tph₂ (8%-40% α-, 0%-25% β-, 25%-84% γ-, and 8%-50% δ-tocopherol). The existence of (mutant) genes for increased levels of individual fatty acids and for different forms and levels of tocopherol enables the development of sunflower hybrids with different oil quality. The greatest progress has been made in developing high-oleic hybrids (>90% oleic acid). There has been considerable work done recently on the development of high-oleic hybrids with altered tocopherol levels, the oil of which will have 10-20 times greater oxidative stability than that of conventional sunflower oil. While sunflower breeders work on developing hybrids with altered oil quality, medical scientists in general and nutritionists in particular will determine the parameters for the use of these novel types of oil that can improve human nutrition and be used in the prevention of cardiovascular diseases.

Le tournesol est l'une des quatre plantes oléagineuses cultivées les plus importantes, et son huile se classe parmi les meilleures huiles végétales. L'huile de tournesol traditionnelle contient généralement jusqu'à 90 % d'acides gras insaturés, soit de l'acide oléique (C 18:1, 16-19 %) et de l'acide linoléique (C 18:2, 68-72 %). L'acide palmitique (C 16:0, 6 %), l'acide stéarique (C 18:0, 5 %) et des traces d'acides myristique (C 14:0), myristoléique (C 14:1), palmitoléique (C 16:1), arachidique (C 20:0), béhénique (C 22:0) et autres forment le reste des acides gras. Grâce aux progrès de la génétique moderne, plus particulièrement les mutations induites, on peut modifier significativement la composition en acides gras de l'huile de tournesol. Le traitement des graines de tournesol par une exposition aux rayons gamma et aux rayons-X a produit des mutants contenant 25-30 % d'acide palmitique. Le traitement des graines de tournesol par exposition aux rayons-X a aussi produit des mutants ayant 30 % d'acide palmitoléique, alors qu'un traitement avec de l'azoture de sodium a produit des mutants contenant 35 % d'acide stéarique. La plus importante mutation a été obtenue par un traitement au DMS (sulfate de diméthyl), qui a produit des génotypes contenant plus de 90 % d'acide oléique. Des mutants ayant une teneur élevée en acide linoléique (>80 %) ont aussi été obtenus en exposant les graines aux rayons-X et à l'EMS. L'huile de tournesol est connue pour sa grande teneur en α-tocophérol (<90 %). Des mutations spontanées régulées par des gènes récessifs modifiant significativement les formes et les taux de tocophérol ont été découvertes.

Document Type: Research article

Publication date: 2008-04-01

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Genetic possibilities for altering sunflower oil quality to obtain novel oils

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