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Effect of temperature on polyunsaturated fatty acid accumulation in soybean seeds

Efeito do acúmulo de ácidos graxos poliinsaturados em sementes de soja

Soybean oil contains around 60 % of polyunsaturated fatty acids, which are responsible for the low oxidative stability of soy-derived products. Soybean lines with low linolenic acid content can be obtained by genetic manipulation; however, a high proportion of the variation in fatty acids content is due to environmental factors. This work aimed to determine the effect of temperature on oil composition and on the activity of the enzymes CDP-choline:1,2-diacylglycerolcholine phosphotransferase (CPT) and acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT), responsible for maintenance of polyunsaturated fatty acids in the cytoplasmic acyl-CoA pool, that is used for oil synthesis in the seeds. CAC-1, a soybean variety with linolenic acid content of about 8 % and CC4, a BC3F4 CAC-1 derived line, with about 4 % linolenic acid, were used. The lines were cultivated under two temperature: 34/28ºC or 22/13ºC - day/night. The seeds were collected along seven development stages, according to their fresh weight. Fatty acid analysis was carried out by gas chromatography and CPT and LPCAT activities were determined by measuring the radioactivity incorporated in their products, phosphatidyl-[14C]choline and phosphatidylcholine-[14C]oleoyl, respectively. Linolenic acid contents were 3.89 and 6.92 % for line CC4 and 7.39 and 12.49 % for variety CAC-1, when submitted to high and low temperature conditions, respectively. Both enzymes were more active, in the development stages analyzed, in seeds produced under low temperature. Kinetics characterization of CPT and LPCAT were conducted previously.

Cholinephosphotransferase; kinetic characterization; linoleic acid; linolenic acid; lysophosphatidylcholine acyltransferase; soybean seed


Brazilian Journal of Plant Physiology Centro de Ciências e Tecnologias Agropecuárias, , Universidade Estadual do Norte Fluminense Darcy Ribeiro - UENF, 28013-602 - Campos dos Goytacazes, RJ - Brazil, Fax: (+55)-22-2739-7116 - Campos dos Goytacazes - RJ - Brazil
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