Nath Ujjal K, Wilmer Jeroen A, Wallington Emma J, Becker Heiko C, Möllers Christian
Department of Crop Sciences, Plant Breeding, Georg-August-Universität Göttingen, Von-Siebold-Str. 8, 37075 Göttingen, Germany.
Theor Appl Genet. 2009 Feb;118(4):765-73. doi: 10.1007/s00122-008-0936-7. Epub 2008 Dec 3.
High erucic acid rapeseed (HEAR) oil is of interest for industrial purposes because erucic acid (22:1) and its derivatives are important renewable raw materials for the oleochemical industry. Currently available cultivars contain only about 50% erucic acid in the seed oil. A substantial increase in erucic acid content would significantly reduce processing costs and could increase market prospects of HEAR oil. It has been proposed that erucic acid content in rapeseed is limited because of insufficient fatty acid elongation, lack of insertion of erucic acid into the central sn-2 position of the triaclyglycerol backbone and due to competitive desaturation of the precursor oleic acid (18:1) to linoleic acid (18:2). The objective of the present study was to increase erucic content of HEAR winter rapeseed through over expression of the rapeseed fatty acid elongase gene (fae1) in combination with expression of the lysophosphatidic acid acyltransferase gene from Limnanthes douglasii (Ld-LPAAT), which enables insertion of erucic acid into the sn-2 glycerol position. Furthermore, mutant alleles for low contents of polyunsaturated fatty acids (18:2 + 18:3) were combined with the transgenic material. Selected transgenic lines showed up to 63% erucic acid in the seed oil in comparison to a mean of 54% erucic acid of segregating non-transgenic HEAR plants. Amongst 220 F(2) plants derived from the cross between a transgenic HEAR line and a non-transgenic HEAR line with a low content of polyunsaturated fatty acids, recombinant F(2) plants were identified with an erucic acid content of up to 72% and a polyunsaturated fatty acid content as low as 6%. Regression analysis revealed that a reduction of 10% in polyunsaturated fatty acids content led to a 6.5% increase in erucic acid content. Results from selected F(2) plants were confirmed in the next generation by analysing F(4) seeds harvested from five F(3) plants per selected F(2) plant. F(3) lines contained up to 72% erucic acid and as little as 4% polyunsaturated fatty acids content in the seed oil. The 72% erucic acid content of rapeseed oil achieved in the present study represents a major breakthrough in breeding high erucic acid rapeseed.
高芥酸油菜籽（HEAR）油因其工业用途而备受关注，因为芥酸（22:1）及其衍生物是油脂化学工业重要的可再生原料。目前市面上的油菜籽品种，其种子油中的芥酸含量仅约为50%。大幅提高芥酸含量将显著降低加工成本，并可能增加HEAR油的市场前景。据推测，油菜籽中芥酸含量受限是由于脂肪酸延长不足、芥酸无法插入三酰甘油主链的中心sn-2位置以及前体油酸（18:1）竞争性去饱和生成亚油酸（18:2）。本研究的目的是通过过量表达油菜籽脂肪酸延长酶基因（fae1），并结合表达来自道氏海蓬子（Limnanthes douglasii）的溶血磷脂酸酰基转移酶基因（Ld-LPAAT）来提高HEAR冬油菜籽的芥酸含量，该基因能使芥酸插入sn-2甘油位置。此外，将低含量多不饱和脂肪酸（18:2 + 18:3）的突变等位基因与转基因材料相结合。与分离的非转基因HEAR植株平均54%的芥酸含量相比，所选转基因株系的种子油中芥酸含量高达63%。在一个转基因HEAR株系与一个低含量多不饱和脂肪酸的非转基因HEAR株系杂交产生的220株F(2)植株中，鉴定出了芥酸含量高达72%且多不饱和脂肪酸含量低至6%的重组F(2)植株。回归分析表明，多不饱和脂肪酸含量降低10%会使芥酸含量增加6.5%。通过分析每个所选F(2)植株收获的五株F(3)植株的F(4)种子，在下一代中证实了所选F(2)植株的结果。F(3)株系的种子油中芥酸含量高达72%，多不饱和脂肪酸含量低至4%。本研究中获得的72%的油菜籽油芥酸含量代表了高芥酸油菜籽育种的一项重大突破。
