Ultrastructure of forming and dormant chlamydospores of Fusarium solani in soil.

Chlamydospores of Fusarium solani f. sp. cucurbitae, F. solani f. sp. phaseoli and F. solani f. sp. pisi formed in soil were recovered at intervals and examined by electron microscopy. Cell wall material outside the newly formed chlamydospore cell wall gradually disintegrated. Protoplasts of chlamydospore cells lyse without prior penetration of the cell wall by microorganisms. The mechanisms of lysis of chlamydospores of F. solani in soil are discussed.