The wild relatives of crops represent a rich reservoir of genes for introducing resilience to climate change into cultivated crops. To introgress genes from Sinapis alba, a wild relative of Brassicaceae, into Brassica juncea, a cultivated member of this family, we initially produced somatic hybrids between the two species and then produced a large number of backcross populations involving the two somatic hybrids (H1 and H2) with Brassica juncea. BC1 progeny were morphologically very similar. However, when they were challenge inoculated with a highly virulent Alternaria brassicae (ITCC No. 2542) culture under in vivo and in vitro conditions in two growing seasons, they showed wide variations in their disease reaction. Of the 40 BC1 lines tested in one season, 36 showed a resistant reaction. BC1F2 progenies derived from these resistant BC1 plants also showed resistance to Alternaria brassicae, indicating stable inheritance of the resistant phenotype. However, BC1F2 progenies showed a wide variation in morphological traits, including plant height, basal branching, leaf thickness, trichome density on leaves and stem. BC1 plants were examined by genomic in-situ hybridization (GISH) to determine their chromosome constitution. All five plants were found to possess 12 strong hybridization signals upon hybridization with a FITC-labeled S. alba-specific probe. GISH studies on BC1F2 plants indicated localized signals in addition to 12 full chromosome hybridization signals, suggesting alien introgressions into B. juncea that requires further validation. The BC2 generation was found to possess half of the haploid set of alien chromosomes. The BC1F2 and BC2 generations were further screened against A. Brassiceae and found to be resistant/tolerant.

中文翻译：

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Sinapis alba + Brassica juncea 的体细胞杂种：回交后代的形态变异、染色体构成和对 Alternaria brasicae 反应的研究

作物的野生近缘种代表了丰富的基因库，可以将气候变化的适应力引入栽培作物中。为了将芥菜科的野生近缘白芥菜的基因渗入该科的栽培成员芥菜中，我们最初在两个物种之间产生了体细胞杂种，然后产生了大量涉及两个体细胞杂种（H1 和H2) 与芥菜。BC1 后代在形态上非常相似。然而，当它们在体内和体外条件下在两个生长季节接受高毒力的芸苔素菌（ITCC No. 2542）培养物的挑战时，它们的疾病反应表现出很大的变化。在一个季节测试的 40 条 BC1 品系中，有 36 条表现出抗性反应。源自这些抗性 BC1 植物的 BC1F2 后代也显示出对 Alternaria brasicae 的抗性，表明抗性表型的稳定遗传。然而，BC1F2 后代在形态性状上表现出很大的变化，包括株高、基部分枝、叶片厚度、叶和茎上的毛状体密度。通过基因组原位杂交 (GISH) 检查 BC1 植物以确定它们的染色体构成。发现所有 5 株植物在与 FITC 标记的 S. alba 特异性探针杂交后都具有 12 个强杂交信号。除了 12 条全染色体杂交信号外，对 BC1F2 植物的 GISH 研究还显示了局部信号，表明外来基因渗入了芥菜，需要进一步验证。BC2 代被发现拥有一半的外来染色体单倍体组。