An unidentified substance(s), provisionally named P310, is produced ill mycelia of Alternaria clzrysa?~then~i, Ascochyta pisi, 0phiol)olz~s gmrrri?zis, Pleospora h e r b a r~~m , and Pyro7zenza omphalodes when sporulation has been induced with near-ultraviolet radiation. This saine s~~b s t a n c e is absent in nori-sporulating colonies grown in darkness. I t is, however, present in unexposed colonies of A . pisi grown on media which are able to support sporulation in the absence of light. Pnlo is extractable with cold absolute ethanol, is water-soluble, passes through a dialysis membrane, is retained on a cation exchange resin, and appears to be composed of a t least four possibly related substances. M a s i m~~m absorption of ,PJI? is between 260 and 340 ~n p (310 m p rnaxim~um) and below 250 rnp. Pa10 niay eslst In an oxidized state for when reduced electrolytically, absorption between 260 and 310 m p is lost. P3LO can be detected spectrophotometricaIly in extracts of color~ies exposed to 6 hours of near-ultraviolet radiation, but not after a 1 hour esposure. Conidiosporcs of A. pisi contain Palo, which may be a "sporulating factor" associated with these spores. The rate of P3l0 production in irradiated colonies appears to be related to length of exposure, yet this substance can be produced in darkness for a limited period following stimulation of colonies by near-ultraviolet radiation. xeither the identity nor the mod.l~s operarzdi of Palo has yet been demonstrated.

No abstract

Cultures of 34 fungi were irradiated at 70° F under continuous exposure to near-ultraviolet light (3100–4000 Å) at 76 microwatts per cm2 for periods ranging from 3 to 10 days. Sporulation was initiated or increased in Ascochyta pinnodella, A. pisi, Alternaria chrysanthemi, A. tenuis, A. zinniae, Botrytis cinerea, Coryneum sp., Epicoccum nigrum, Epicoccum sp., Fusarium oxysporum, F. nivale, F. roseum, F. solani, Gliocladium sp., Helminthosporium avenae, Mycosphaerella pinodes, Ophiobolus graminis, Piricularia oryzae, Phoma herbarum var. medicaginis, P. trifolii, Phoma spp., Phyllosticta sp. Pyrenochaeta terrestris, Septoria tritici, Stemphyllium botryosum, S. trifolii, Wojinowicia graminis, and Verticillium albo-atrum. H. oryzae formed conidia only when irradiation was followed by a dark period. Kabatiella caulivora and H. sativum sporulated as well in darkness as under irradiation. Sclerotia of Typhula spp. produced sporophores under a 12-hour dark, 12-hour ultraviolet light cycle at 41° F. When eight ultraviolet light-sensitive species were irradiated on various media, with few exceptions sporulation was stimulated irrespective of substrate. Irradiation of fungi under near-ultraviolet and artificial daylight fluorescent lamps stimulated sporulation equally well. When, however, near-ultraviolet and blue wave lengths were filtered from daylight fluorescent lamp radiation, sporulation was absent or much reduced in most species. Irradiation of colonies on a 12-hour dark, 12-hour ultraviolet light cycle caused zoning in the majority of species. Zoning was absent in colonies cultured under continuous exposure or under darkness.

No abstract

Alternaria dauci, A. tomato, Cercosporella herpotrichoides, Fusarium nivale, Helminthosporium catenarium, and Stemphylium botryosum, all Fungi Imperfecti, were grown on temperature gradient plates (5–40 °C) under different regimes of near-ultraviolet radiation (320–420 nm) and darkness. None of the fungi normally sporulated in darkness on the media used. The effects of interaction of temperature and near-ultraviolet radiation (NUV) on sporulation were significant for all six fungi. The fungi were grouped into two categories, "Diurnal Sporulators" (A. dauci, A. tomato, and S. botryosum) and "Constant Temperature Sporulators" (F. nivale, H. catenarium, and C. herpotrichoides). The "Diurnal Sporulators" have two distinct phases of photosporogenesis, an "inductive phase" leading to the formation of conidiophores, and a "terminal phase" resulting in the formation of conidia. The "inductive phase" is stimulated by NUV and operative at relatively high temperatures, while the "terminal phase" is strongly inhibited by NUV and blue light, and is operative at lower temperatures. In S. botryosum the "terminal phase" was completely inhibited by light at high temperatures but only partially inhibited at low temperatures.The "Constant Temperature Sporulators" in contrast, have a lower optimum temperature range for sporulation and show no clear separation of photosporogenesis into two distinct phases. Sporulation in this group is abundant under continuous exposure to NUV though it is even more abundant when exposure is followed by darkness.A new phenomenon, that of "high temperature induction" of sporulation, was observed in colonies of A. tomato and A. dauci. Relatively high temperatures caused these fungi to produce conidiophores in darkness, though only when the temperature was lowered did conidia form on the conidiophores. The amount of sporulation caused by "high temperature induction" was less than that caused by exposure to NUV.