Exogenous carbon and nitrogen requirements for chlamydospore germination by Fusarium solani: dependence on spore density

Chlamydospores were formed on germ tubes of macroconidia of F. solani after germination at 3 × 10 5 conidia/ml in an inorganic salt solution (pH 5.7) containing glucose (40 μg C/ml) plus NH 4 Cl (2.6 μg N/ml), and at 3 × 10 3 conidia/ml in salt solution containing no glucose or NH 4 Cl. After 5 days, chlamydospores formed in the low conidial density system required an exogenous source of carbon for high germination, whereas chlamydospores formed in the high conidial density system required both exogenous carbon and nitrogen for high germination. Chlamydospores formed in the high conidial density system did not require exogenous nitrogen for high germination when the spore density (chlamydospores plus some ungerminated conidia) was reduced from 3 × 10 5 to 3 × 10 4 spores/ml; high germination was observed at 3 × 10 3 spores/ml in the absence of both exogenous carbon and nitrogen.