Effects of ozone on conidiophores and conidia of alternaria solani.

Abstract

Ozone at 0.1 ppm for 4 hr or at 1.0 ppm for 2 hr stopped elongation of conidiophores of Alternaria solani, caused their apical cells to swell, and often collapsed the cell wall at their tips. These conidiophores began to elongate again when they were removed from ozone and exposed to light to prevent sporulation. Usually the collapsed end wall was sloughed, and the new cells often grew at an angle to the original axis of the conidiophore. Sometimes breaks appeared in the pigmented layers of the walls of the swollen cells. Ozone-damaged conidiophores, given the necessary dark period, sporulated normally. If sporulating cultures were exposed to 1.0 ppm ozone for 30 min, the conidia began to germinate while still attached to the conidiophores. Conidiophores treated with a subtoxic dose of a sulfhydryl-binding reagent (..cap alpha..-iodoacetamide) became more susceptible to ozone. Exposure to pure oxygen at either 1 or 4 atm pressure for 4 hr caused no visible damage to conidiophores of A. solani.