Sporulation in the fungus Verticillium agaricinum: reversal of blue light inhibition by ultraviolet radiation

In colonies ranging from 3- to 5-days-old, light in general stimulates conidiation in Verticillium , including V. agaricinum and several strains of V. albo-atrum . However, when growth was started by inoculating with conidial suspension spread evenly over the plate, it was found that blue light inhibited conidiation in our strain of V. agaricinum . The most light-sensitive phase was around 9 h after inoculation. A broad band blue light pulse of 10 J m super(-2) saturated the response. The inhibitory effect of blue light could be reversed by a subsequent ultraviolet (UV) radiation, but a further effect of blue light was lost after the UV pulse. Blue light inhibition was also prevented by UV radiation administered before the blue light.