Interspecific F1 hybrids were obtained from crosses between two Ogura cytoplasmic male sterility (Ogura CMS) broccoli lines (B14 and 137) and a rapeseed restorer line to introgress the Ogura CMS’s fertility-restoration gene Rfo from rapeseed into broccoli. Ten Rfo-positive interspecific, triploid plant progenies, phenotypically between rapeseed and broccoli, were obtained but still contained multiple rapeseed genes, with reduced fertility and seed setting potential under natural pollination. For fertility and seed setting improvement, successive backcrosses with broccoli were carried out to yield BC2 progenies. Screening revealed six plants with Rfo among 25 BC2 progenies, which were investigated for agronomic traits, ploidy determination, pollen viability and SSR (simple sequence repeat) markers to evaluate for ideal individuals closer to broccoli. Pollen viability tests were carried out at different stages for various hybrid parents. The results were as follows: 137-F1 (68.54%) > B14-F1 (65.32%) > 137-BC1 (48.15%) > B14-BC1 (32.41%). Although there were significant differences among the BC1 and BC2 individuals, the genetic background of BC2 was closer to the parent broccoli compared with that of BC1 plants. The existence of the Rfo gene in broccoli not only facilitates broccoli germplasm innovation, combination of interspecific hybridization and backcrossing, but may also shed light on trait segregation in different generations.

中文翻译：

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Ogura CMS 生育力恢复的种间杂种和来自西兰花和油菜籽杂交的回交后代的表征

从两个 Ogura 细胞质雄性不育 (Ogura CMS) 西兰花品系（B14 和 137）和一个油菜籽恢复系之间的杂交获得种间 F1 杂种，以将 Ogura CMS 的生育恢复基因 Rfo 从油菜籽渗入西兰花。获得了 10 个 Rfo 阳性种间三倍体植物后代，表型介于油菜籽和西兰花之间，但仍含有多个油菜籽基因，在自然授粉下生育力和结实潜力降低。为了提高育性和结实率，与西兰花进行连续回交以产生 BC2 后代。筛选显示 25 个 BC2 后代中有 6 株具有 Rfo，对其农艺性状、倍性测定、花粉活力和 SSR（简单序列重复）标记来评估更接近西兰花的理想个体。在不同阶段对各种杂种亲本进行花粉活力测试。结果如下：137-F1（68.54%）>B14-F1（65.32%）>137-BC1（48.15%）>B14-BC1（32.41%）。尽管BC1和BC2个体之间存在显着差异，但与BC1植物相比，BC2的遗传背景更接近亲本西兰花。西兰花中Rfo基因的存在不仅有利于西兰花种质创新、种间杂交和回交的结合，而且还可以揭示不同世代的性状分离。B14-F1 (65.32%) > 137-BC1 (48.15%) > B14-BC1 (32.41%)。尽管BC1和BC2个体之间存在显着差异，但与BC1植物相比，BC2的遗传背景更接近亲本西兰花。西兰花中Rfo基因的存在不仅有利于西兰花种质创新、种间杂交和回交的结合，而且还可以揭示不同世代的性状分离。B14-F1 (65.32%) > 137-BC1 (48.15%) > B14-BC1 (32.41%)。尽管BC1和BC2个体之间存在显着差异，但与BC1植物相比，BC2的遗传背景更接近亲本西兰花。西兰花中Rfo基因的存在不仅有利于西兰花种质创新、种间杂交和回交的结合，而且还可以揭示不同世代的性状分离。