Inhibition of chlamydospore production in Fusarium oxysporum by ammonia and high ion concentrations

Abstract
NH4Cl in a Tris-HCl buffered solution inhibited chlamydospore production in germinated macroconidia of F. oxysporum. KCl, CaCl2 and buffer solutions at higher concentrations were also inhibitory but to a lesser extent. At fixed concentrations of NH4Cl and KCl mixed at different ratios, chlamydospore production decreased with increasing concentrations of NH3/NH4+. This effect was stronger at pH 8.5 than at pH 7.5, suggesting that NH3 is the active component. NH3 and high ion concentrations can be inhibitory to the production of chlamydospores in salt solutions. No qualitative differences were found between chlamydospores formed at different concentrations of ammonia.