Eliminating expression of erucic acid-encoding loci allows the identification of "hidden" QTL contributing to oil quality fractions and oil content in Brassica juncea (Indian mustard)
Eliminating expression of erucic acid-encoding loci allows the identification of "hidden" QTL contributing to oil quality fractions and oil content in Brassica juncea (Indian mustard)
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DOI：
10.1007/s00122-010-1515-2
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发表时间：
2011-04-01
影响因子：
5.4
通讯作者：
Pental, Deepak
中科院分区：
文献类型：
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作者：
Jagannath, Arun;Sodhi, Yashpal Singh;Pental, Deepak
含油量和油质组分（即油酸、亚油酸和亚麻酸）受到芥酸途径的强烈影响。籽油中芥酸的低含量使油酸含量达到营养所需的水平，但也增加了亚油酸和亚麻酸组分，并降低了印度芥菜（芥菜）的含油量。本研究通过回交育种，对高芥子气的印度品种（Varuna）、低芥子气的东欧品种（Heera）和零芥子气的印度品种（泽-Varuna）的油质组分进行了表型变异分析，结果表明，Varuna中亚油酸和亚麻酸含量较低是由于芥子气活性途径引起的底物限制，而不是由于较弱的等位基因或酶限制。为了确定在零胁迫条件下提高含油量和维持理想油质组分水平的补偿位点，我们在两个独立的F1双单倍体（F1DH）定位群体上对上述性状进行了定量性状位点（QTL）定位。其中一个群体由依芥酸含量（erucic acid content， SE）进行分离的植株组成，该群体较早被用于构建芥菜数个影响产量性状的连锁图谱和QTL定位。第二种群由零芥酸个体（ZE）组成，本研究构建了基于扩增片段长度多态性（AFLP）的框架连锁图谱。通过对ZE群体中油质组分和含油量的QTL定位，我们发现了对上述性状有贡献的新位点。这些位点没有与脂肪酸去饱和酶2 （FAD2）、脂肪酸去饱和酶3 （FAD3）或脂肪酸延长酶（FAE）基因的定位位点共定位，而在SE群体中，发现主要QTL与FAE基因的定位位点一致。在ZE群体中发现的一些新位点在SE群体中被检测为“弱”贡献位点（LOD < 2.5），由于芥酸基因的多效性作用，它们对这些性状的贡献被“掩盖”了。该研究中发现的新基因座现在可用于改善零酸条件下芥菜的油质参数和含油量。
Oil content and oil quality fractions (viz., oleic, linoleic and linolenic acid) are strongly influenced by the erucic acid pathway in oilseed Brassicas. Low levels of erucic acid in seed oil increases oleic acid content to nutritionally desirable levels, but also increases the linoleic and linolenic acid fractions and reduces oil content in Indian mustard (Brassica juncea). Analysis of phenotypic variability for oil quality fractions among a high-erucic Indian variety (Varuna), a low-erucic east-European variety (Heera) and a zero-erucic Indian variety (ZE-Varuna) developed by backcross breeding in this study indicated that lower levels of linoleic and linolenic acid in Varuna are due to substrate limitation caused by an active erucic acid pathway and not due to weaker alleles or enzyme limitation. To identify compensatory loci that could be used to increase oil content and maintain desirable levels of oil quality fractions under zero-erucic conditions, we performed Quantitative Trait Loci (QTL) mapping for the above traits on two independent F1 doubled haploid (F1DH) mapping populations developed from a cross between Varuna and Heera. One of the populations comprised plants segregating for erucic acid content (SE) and was used earlier for construction of a linkage map and QTL mapping of several yield-influencing traits in B. juncea. The second population consisted of zero-erucic acid individuals (ZE) for which, an Amplified Fragment Length Polymorphism (AFLP)-based framework linkage map was constructed in the present study. By QTL mapping for oil quality fractions and oil content in the ZE population, we detected novel loci contributing to the above traits. These loci did not co-localize with mapped locations of the fatty acid desaturase 2 (FAD2), fatty acid desaturase 3 (FAD3) or fatty acid elongase (FAE) genes unlike those of the SE population wherein major QTL were found to coincide with mapped locations of the FAE genes. Some of the new loci identified in the ZE population could be detected as 'weak' contributors (with LOD < 2.5) in the SE population in which their contribution to the traits was "masked" due to pleiotropic effects of erucic acid genes. The novel loci identified in this study could now be used to improve oil quality parameters and oil content in B. juncea under zero-erucic conditions.