种间杂交的主要障碍是F1代的不育性.A major barrier to interspecific hybridization is sterility in the F 1 progeny.因此,向日葵细胞质雄性不育性的研究备受关注.That is why cytoplasmic male sterility ( CMS ) in sunflower is the research focus through years....

“不育性”的英语可以翻译为：infertility，sterility ...