The interspecific cross between improved cytoplasmic male sterility (CMS)Brassica campestris ssp. pekinensis (Lour.) Olsson and B. oleracea var.acephala DC. aims to obtain kale male sterile lines and enrich Chinese cabbage genetic resources. The results indicated that there were serious segregations between the 2 parents, so as to descendants could not be obtained by routine pollination methods. Otherwise, interspecific hybrids have been obtained by young embryos culture in vitro and the best time of embryo rescue was the 9 - 11 day after pollination. Interspecific embryo collapsed at sphere stage, with endosperm nuclei being surrounded by cell walls. The morphology, fertility, microspore growth, vernalization and numbers of chromosome were conducted to prove the truth of interspecific hybrids. Leaf morphology was intermediate of the 2 parents. Anther shape and plumpness, nectary volume and numbers were matroclinous. The male sterility showed 100% both in degree and ratio.  Interspecific hybrids microspore aborted clearly from mononuclear to dinuclear stage.  Vernalization was also intermediate of the 2 parents. Chromosome number of hybrids was confirmed to be 2n = 19, which was the total count of gametophyte chromosome of 2 parents. Also, we obtained BC₁ which was from F₁×kale, by pollinated several times, while the average compatibility index was only 0.0014. There were sluggish chromosomes in BC₁ PMCs anaphase.

Key words: CMS Chinese cabbage, kale embryo culture, chromosome, F_1, BC_1.