On the Use of Microspores for Genetic Modification

Summary

The practicality of using microspores in mass culture for mutant selection at the haploid level is explored with reference to two culture systems, one giving high yields of embryos (Datura innoxia), the other, calluses (Hordeum vulgare). Both rely on a stress pretreatment to switch the spores into morphogenic competence before the anthers are dissected out. Removal of spores from the anthers is either mechanical (Datura) or by natural dehiscence (Hordeum). Up to 1.0% of spores give embryos in Datura, 4% give calluses in Hordeum. Ways of improving culture efficiency are discussed. It is estimated that with such improvements, mutant plants could be recovered in Datura at a rate of 10 per person per year. Use of the Hordeum system is restricted by a low frequency of green-plant regeneration from the calluses. Mutant selection would be feasible but costly in terms of both personnel and cultivation of plants. It is concluded that for many crop species, mutant selection at the microspore level would be impractical owing to the small size of anthers, difficulties of accumulating populations large enough and at a uniform developmental stage, and the need for plants grown under standardized conditions. A more general application is seen in the genetic manipulation of individual cells.