Brassica napus is an allopolyploid plant, derived from spontaneous hybridization between Brassica rapa and Brassica oleracea. Intensive breeding has led to a significant reduction in genetic and phenotypic diversity within this species. Newly resynthesized hybrids from progenitor species may restore some diversity in B. napus, but they often are chromosomally and phenotypically unstable. Using fluorescence in situ hybridization, we tested chromosome constitutions in a range of new allopolyploids resynthesized from various parental species. A majority of these allopolyploids were euploid, with the expected chromosome numbers and constitutions, but deviations were also identified. We detected a low level of intergenomic rearrangements in analyzed hybrids and a high level of changes in rDNA loci. Our study revealed a significant effect of maternal cross combination on loss of 35S rDNA loci, especially when B. rapa was the maternal parent. The studied lines were characterized by diversified of pollen viability. In the analyzed hybrids, the erucic acid level in the seed oil ranged from 0 to 43.4% and total glucosinolate content in seeds ranged from 24.3 to 119.2 μmol g⁻¹. Our study shows that cytogenetic analysis of B. napus resynthesized hybrids would be useful in breeding for the selection of lines with important agricultural characters and genetically stable stock seed production.

中文翻译：

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FISH 揭示的再合成甘蓝型油菜中的染色体不稳定性。

欧洲油菜是一种异源多倍体植物，源自油菜和甘蓝之间的自发杂交。集约化育种导致该物种的遗传和表型多样性显着减少。来自祖先物种的新重新合成的杂种可能会恢复欧洲油菜的一些多样性，但它们通常在染色体和表型上不稳定。使用荧光原位杂交，我们测试了从各种亲本重新合成的一系列新异源多倍体中的染色体构成。这些异源多倍体中的大多数是整倍体，具有预期的染色体数量和构成，但也发现了偏差。我们在分析的杂种中检测到低水平的基因组间重排和 rDNA 基因座的高水平变化。我们的研究揭示了母体交叉组合对 35S rDNA 基因座丢失的显着影响，尤其是当B. rapa是母亲的父母。研究的品系的特点是花粉活力多样化。在分析的杂种中，种子油中的芥酸水平范围为 0 至 43.4%，种子中总硫代葡萄糖苷含量范围为 24.3 至 119.2 μmol g ^-1。我们的研究表明，欧洲油菜再合成杂种的细胞遗传学分析将有助于选育具有重要农业性状和遗传稳定的种子生产的品系。