Journal Article

Temperature-dependent endogenous oxygen concentration regulates microsomal oleate desaturase in developing sunflower seeds

Hardy Rolletschek, Ljudmilla Borisjuk, Alicia Sánchez-García, Cecilia Gotor, Luis C. Romero, José M. Martínez-Rivas and Manuel Mancha

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 58, issue 12, pages 3171-3181
Published in print September 2007 | ISSN: 0022-0957
Published online September 2007 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/erm154
Temperature-dependent endogenous oxygen concentration regulates microsomal oleate desaturase in developing sunflower seeds

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Oleoyl-phosphatidylcholine desaturase (FAD2) is a key enzyme involved in fatty acid desaturation in oilseeds, which is affected by environmental temperature. The results of this study show that FAD2 is regulated in vivo via temperature-dependent endogenous oxygen concentrations in developing sunflower (Helianthus annuus L.) seeds. By combining in vivo oxygen profiling, in situ hybridization of FAD2 genes, an assay of energy status, fatty acid analysis, and an in vitro FAD2 enzyme activity assay, it is shown that: (i) the oil-storing embryo is characterized by a very low oxygen level that is developmentally regulated. Oxygen supply is mainly limited by the thin seed coat. (ii) Elevations of external oxygen supply raised the energy status of seed and produced a dramatic increase of the FAD2 enzyme activity as well as the linoleic acid content. (iii) A clear negative correlation exists between temperature and internal oxygen concentration. The changes occurred almost instantly and the effect was fully reversible. The results indicate that the internal oxygen level acts as a key regulator for the activity of the FAD2 enzyme. It is concluded that a major mechanism by which temperature modifies the unsaturation degree of the sunflower oil is through its effect on dissolved oxygen levels in the developing seed.

Keywords: Helianthus annuus; linoleic acid; oleic acid; oleoyl-phosphatidylcholine desaturase (FAD2); oxygen regulation; sunflower seeds; temperature regulation

Journal Article.  6013 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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