Microspore embryogenesis was induced in anthers of Brassica oleracea L. var. acephale D.C. cv. 'Polkow' (autotetraploid marrowstem kale) cultured under conditions similar to those previously developed for B. campestris and B. napus. Embryogenesis was stimulated by an initial high temperature culture treatment with maximal embryo yields obtained when anthers were cultured at 35 °C for one day prior to maintenance at 25 °C. Although most of the microspore-derived embryos failed to develop directly into plantlets, regeneration could be achieved from cultured hypocotyl explants. More than 60% of the regenerates had small, sterile flowers and cytological analysis of some of these plants revealed that they were dihaploids (2n = 2x = 18). Plant regeneration could be induced from dihaploid stem explants, thereby providing a potential method for propagation and maintenance of sterile material.
