Photoinduction des périthèces du Nectria galligena. I. Influence de la lumière blanche

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Abstract
The ascocarps of N. galligena Bres. were induced by exposures to white light with variations in time, rhythm and intensity. Perithecia could be photoinduced by a single 12 h photoperiod at 10 .mu.W cm-2 or by continuous irradiations at 750 .mu.W cm-2 for 30 days. These light requirements varied according to the stage of sexual development: perithecia were initiated by a 12 h exposure to light between the 7th and 8th day; daily 12 h exposures between the 7th and 22nd days were necessary for the best ascocarp development. Ascospore formation did not require light exposure. Light did not produce its effect on sexual reproduction before the 7th day of mycelial growth; its maximum stimulation occurred between the 7th and 10th day. Biological photoresponses were similar to the sexual induction which appeared in the dark after the addition of mycosporine (P310) to the growth medium. Mycosporine evidently acted mainly on ascocarp initiation; complete sexual differentiation was achieved by some other photoinduced mycelial products.