Interstrain spheroplast fusion of Alternaria alternata

Summary Auxotrophic and drug resistant colonies of Alternaria alternata were selected following UV mutagenesis of spheroplasts and genetic transformation with pDH25. Intrastrain cell fusion of certain A. alternata parental strains induced by polyethylene glycol occurred at an average rate of 0.35%; interstrain fusions occurred at a rate of 0.08%. Mitotic recombination resulted from UV mutagenesis of spheroplasts from several fusants from 6hy1 × 1ar1. Fusants synthesized different levels of the cyclic tetrapeptide, tentoxin; some colonies produced higher levels than either parent. These results demonstrate that spheroplast fusion may have a potential application for genetic analysis of secondary metabolite production and for strain improvement in A. alternata.Mention of a trademark of proprietary product does not constitute a guarantee or warranty by the U. S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be suitable.