Acyl CoA profiles of transgenic plants that accumulate medium-chain fatty acids indicate inefficient storage lipid synthesis in developing oilseeds
Acyl CoA profiles of transgenic plants that accumulate medium-chain fatty acids indicate inefficient storage lipid synthesis in developing oilseeds
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DOI：
10.1046/j.1365-313x.2002.01440.x
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发表时间：
2002-11-01
期刊：
影响因子：
7.2
通讯作者：
Graham, IA
中科院分区：
文献类型：
--
作者：
Larson, TR;Edgell, T;Graham, IA
对用负责合成中链或长链脂肪酸的基因转化的几种甘蓝型油菜品系进行了检查，以确定这些脂肪酸随后在种子脂质中积累的限制因素。对癸酸 (10:0) 积累系的检查显示，与从相同组织中分离的长链酰基 CoA 相比，种子发育过程中 10:0 CoA 的浓度不成比例地高，这表明 10:0 CoA 与种子脂质的不良掺入限制了 10:0 脂肪酸的积累。对于高 12:0 系中的十二酰 (12:0) CoA 和脂肪酸也存在这种关系，但对于高 18:0 系中的十八烷酸 (18:0) CoA 和脂肪酸则没有这种关系。对转基因甘蓝型油菜和中链硫酯酶和 3-酮酰基-ACP 合酶转基因的来源植物——萼花在不同发育阶段的种子中的 10:0 CoA 和脂肪酸比例进行比较，结果表明，与转基因甘蓝型油菜相比，萼花更有效地将 10:0 CoA 掺入种子脂质中。此外，在 8:0/10:0 品系的种子发育过程中，β-氧化和乙醛酸循环活性并未增加至高于野生型水平，这表明脂质分解代谢并未因 10:0 CoA 浓度升高而被诱导。总而言之，这些数据表明，被工程改造以合成中链脂肪酸的转基因植物可能缺乏必要的机制，例如特定的酰基转移酶，以将这些脂肪酸有效地掺入种子脂质中。
Several Brassica napus lines transformed with genes responsible for the synthesis of medium- or long-chain fatty acids were examined to determine limiting factor(s) for the subsequent accumulation of these fatty acids in seed lipids. Examination of a decanoic acid (10:0) accumulating line revealed a disproportionately high concentration of 10:0 CoA during seed development compared to long-chain acyl CoAs isolated from the same tissues, suggesting that poor incorporation of 10:0 CoA into seed lipids limits 10:0 fatty acid accumulation. This relationship was also seen for dodecanoyl (12: 0) CoA and fatty acid in a high 12:0 line, but not for octadecanoic (18:0) CoA and fatty acid in a high 18:0 line. Comparison of 10:0 CoA and fatty acid proportions from seeds at different developmental stages for transgenic B. napus and Cuphea hookeriana, the source plant for the medium- chain thioesterase and 3-ketoacyl-ACP synthase transgenes, revealed that C. hookeriana incorporates 10: 0 CoA into seed lipids more efficiently than transgenic B. napus. Furthermore, beta-oxidation and glyoxylate cycle activities were not increased above wild type levels during seed development in the 8:0/10:0 line, suggesting that lipid catabolism was not being induced in response to the elevated 10:0 CoA concentrations. Taken together, these data suggest that transgenic plants that are engineered to synthesize medium- chain fatty acids may lack the necessary mechanisms, such as specific acyltransferases, to incorporate these fatty acids efficiently into seed lipids.