Isolated-microspore Culture of F_1 Hybrids between Brassica oleracea var. capitata and var. italica

Microspore culture of twenty F1 hybrids between cabbage (Brassica oleracea var. capitata) and broccoli (Brassica oleracea var. italica) and their corresponding parents were carried out, and the major factors affectingmicrospore embryogenesis was investigated. Liquid medium 1/2NLN was used for microspore culture, whichcontained 0.5 mg L-1 NAA, 0.05 mg L-1 BA, 5 mg L-1 AgNO3, 0.2 mg L-1 2,4-D and 0.1 mg L-1 active carbon. Results showed that fourteen F1 hybrids could produce embryoids, the induced frequency being 70%. The highest embryo producing rate appeared in'Luzhou808×Xiabao' with averaging 16.2 embryos developed per flower bud. The optimum period of microspores for embryoid development was from late uninucleate (late anaphase I) stage tobinucleate (anaphase II) stage. The heat-shock treatment at 34℃ for 2 days was beneficial for stimulatingsymmetric unclean division of microspore cells. The embryo production was significantly increased in liquidmedium containing 170 g L-1 sucrose for 3 days and then by adding low sucrose content (110 g L-1).