Novel insights into seed fatty acid synthesis and modification pathways from genetic diversity and quantitative trait loci analysis of the Brassica C genome
Novel insights into seed fatty acid synthesis and modification pathways from genetic diversity and quantitative trait loci analysis of the Brassica C genome
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DOI：
10.1104/pp.107.096172
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发表时间：
2007-08-01
期刊：
影响因子：
7.4
通讯作者：
King, Graham J.
中科院分区：
文献类型：
--
作者：
Barker, Guy C.;Larson, Tony R.;King, Graham J.
脂肪酸合成和修饰途径的自然遗传变异决定了植物油的组成，植物油是人类饮食和可再生产品的主要成分。基于已知的途径，我们结合代谢产物的多样性和遗传分析来推断由不同基因座编码的酶的存在，并将这些酶与特定的伸长步骤或亚途径联系起来。共有107个品系代表不同的油菜籽脂肪醇类物质，对18种种子脂肪酸产物表现出较大的变异。使用散点图的相关矩阵和计算相对步骤产量，证明了单个生化步骤内的遗传变异对后续产品的影响。令人惊讶的是，二倍体甘蓝分离种群的个体脂肪酸变异范围与整个基因库相似。这使得能够识别22个数量性状基因座(QTL)，这些QTL与叶绿体的活性、合成的早期阶段、脱饱和和伸长酶相关。4个QTL定位于合成的早期阶段，7个定位于亚途径特异性或一般伸长酶活性，1个定位于酮酰基载体蛋白合成酶，2个分别定位于脂肪酸去饱和酶和去饱和酶或脂肪酰基载体蛋白硫酯酶。另外10个QTL效应明显，但没有被赋予特定的功能。当检测到多个子途径中的相反行为时，我们推断出底物和产物的特定组合的QTL特异性。QTL的酶功能定位与已知的一些芥菜科候选基因的位置和拟南芥基因组的共线区域是一致的。
Natural genetic variation in fatty acid synthesis and modification pathways determine the composition of vegetable oils, which are major components of human diet and renewable products. Based on known pathways we combined diversity and genetic analysis of metabolites to infer the existence of enzymes encoded by distinct loci, and associated these with specific elongation steps or subpathways. A total of 107 lines representing different Brassica genepools revealed considerable variation for 18 seed fatty acid products. The effect of genetic variation within a single biochemical step on subsequent products was demonstrated using a correlation matrix of scatterplots, and by calculating relative step yields. Surprisingly, diploid Brassica oleracea segregating populations had a similar range of variation for individual fatty acids as across the whole genepool. This allowed identification of 22 quantitative trait loci (QTL) associated with activity in the plastid, early stages of synthesis, desaturation, and elongases. Four QTL were assigned to early stages of synthesis, seven to subpathway specific or general elongase activity, one to ketoacyl acyl-carrier protein synthetase, and two each to fatty acid desaturase and either desaturase or fatty acyl-carrier protein thioesterase. An additional 10 QTL had distinct effects but were not assigned specific functions. Where contrasting behavior in more than one subpathway was detected, we inferred QTL specificity for particular combinations of substrate and product. The assignment of enzyme function to QTL was consistent with the known position of some Brassicaeae candidate genes and collinear regions of the Arabidopsis (Arabidopsis thaliana) genome.