Development of haploid cell lines from immature barley,Hordeum vulgare, embryos.

Callus and suspension cell lines were derived from haploid barley embryos produced by the Bulbosum method. Embryos 1 to 2 mm long callused on medium containing a low concentration of 2,4-dichlorophenoxyacetic acid (2,4-D). Fast-growing nodular, beige callus (Type 1), slow-growing, light brown, watery callus (Type 2) and a dense, light yellow, nodular callus (Type 3) were recovered. Type 3 callus was embryogenic and was produced on embryos 1 to 2 mm in length. Although callus cultures gradually became polyploid, a small proportion of haploid cells was retained and the majority of regenerated plantlets were haploid. The organogenic potential of long-term (Type 1) callus cultures was generally low and decreased with time. Attempts to inducede novo shoot formation in Type 1 cultures were not successful.