Brassica napus (canola) is the second largest oilseed crop in the world. It is among the first crops to be genetically transformed, and genetically modified cultivars are in commercial production at very significant levels. Despite the early lead with respect to transgenesis, there remain cultivars that are recalcitrant to transformation. To address this, we have conducted an elaborate investigation of the conditions for regenerating shoots from hypocotyl explants from four genetic lines: Invigor 5020, Westar and Topas as well as a microspore culture derived line of Topas (Line 4079). We analyzed the effect of hormonal combinations in regeneration medium, donor plant age and explant type on the regeneration capacity of these plants. The analysis showed that hypocotyls of eight-day-old seedlings grown on media supplemented with 1mg/L dinitrophenylhydrazine (2,4-D) produced the most shoots. Globular somatic embryos emerged following two weeks of 2,4-D treatment. When transferred to the medium containing 5mg/L benzyladenine (BA), approximately 82% of embryos produced shoots within six weeks. Invigor plants were shown to regenerate more efficiently than Topas; the number of plantlets regenerated from Invigor was approximately 40-50% more as compared to Topas or Line 4079. When hypocotyl explants were co-cultivated with the Agrobacterium strain GV3101 harboring a binary vector carrying a firefly luciferase reporter gene (LUC), significant numbers of plantlets were LUC-positive in a luciferase assay. Frequency of such plants were: Invigor 5020 (54.2 ± 2.5%), Westar (53.7 ± 5.3), Topas (16.0 ± 0.24) and Line 4079 (13.4 ± 4).

中文翻译：

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用于遗传转化的欧洲油菜（canola）外植体再生的优化

欧洲油菜（canola）是世界上第二大油料作物。它是最早进行基因改造的作物之一，并且转基因品种正以非常显着的水平投入商业生产。尽管在转基因方面处于早期领先地位，但仍有一些品种难以转化。为了解决这个问题，我们对从四个遗传系的下胚轴外植体再生芽的条件进行了详尽的研究：Invigor 5020、Westar 和 Topas 以及小孢子培养衍生的 Topas 系（4079 系）。我们分析了再生培养基中激素组合、供体植物年龄和外植体类型对这些植物再生能力的影响。分析表明，在补充有 1mg/L 二硝基苯肼 (2,4-D) 的培养基上生长的 8 天龄幼苗的下胚轴产生最多的芽。在 2,4-D 治疗两周后出现了球状体细胞胚胎。当转移到含有 5mg/L 苄基腺嘌呤 (BA) 的培养基中时，大约 82% 的胚胎在六周内产生了芽。与 Topas 相比，Invigor 植物的再生效率更高；与 Topas 或 Line 4079 相比，从 Invigor 再生的小植株数量大约多 40-50%。当将下胚轴外植体与含有携带萤火虫荧光素酶报告基因 (LUC) 的二元载体的农杆菌菌株 GV3101 共培养时，显着数量的幼苗在荧光素酶测定中是 LUC 阳性的。此类植物的频率为：Invigor 5020 (54.2 ± 2.5%)、Westar (53.7 ± 5.3)、