The effect of monochromatic radiation in the range 350 to 750 nm on the carotenogenesis in Verticillium agaricinum

An action spectrum for carotenogenesis in V. agaricinum has maxima at 395, 433, 660 and 737 nm. In a previous study it had been shown that a light‐minus‐dark difference spectrum of a crude extract from V. agaricinum had maxima at 390 and 420 nm, and furthermore a red, far‐red interaction suggesting phytochrome involvement has been proposed. All these data suggest that there may be at least two photoreceptor systems operating in the photoinduction process here; one for the near‐ultraviolet (UV‐A)‐mediated carotenogenesis, presumably a novel pigment, and the other for the red, far‐red region, most likely phytochrome.