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

Abstract

Chlamydospores were formed on germ tubes of macroconidia of F. solani after germination at 3 × 105 conidia/ml in an inorganic salt solution (pH 5.7) containing glucose (40 μg C/ml) plus NH4Cl (2.6 μg N/ml), and at 3 × 103 conidia/ml in salt solution containing no glucose or NH4Cl. 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 × 105 to 3 × 104 spores/ml; high germination was observed at 3 × 103 spores/ml in the absence of both exogenous carbon and nitrogen.