TEMPERATURE AND MYCOCHROME SYSTEM IN NEAR‐UV LIGHT INDUCIBLE AND BLUE LIGHT REVERSIBLE PHOTOINDUCTION OF CONIDIATION IN Alternaria tomato*

Abstract

Abstract— When dark‐grown colonies were exposed to near‐UV light, conidiophore formation was induced, and conidia developed during a subsequent dark period. Simultaneous exposure to near‐UV and blue light inhibited induction of conidiation. The inductive effect of near‐UV light irradiation was greatly enhanced by treating colonies with low temperatures for 4 h during the 2nd‐6th hour of incubation in the dark following inductive irradiation: the enhancement was greatest at 21°C. The extent of inhibition by blue light increased with the temperature between 10 and 28°C. This diminution by low temperature was greatest when colonies previously kept at a low temperature were exposed to inductive irradiation: the longer the duration between inductive irradiation and temperature treatment, the lower the diminution. Higher fluences of blue light were required to suppress conidial induction at lower temperature. Thus, it is evident that the inductive effect of near‐UV light irradiation on conidiation and the suppressive effect of blue light irradiation are each responsive to different temperatures applied at different times.

Influence of light on growth, conidiation and fumonisin production by Fusarium verticillioides

“…Under this condition, in which the vegetative growth of the mycelium is not supported, the conidiation is promoted. The same conclusion emerged from a work from Kumagai (1989), who reported an inductive effect of near-UV light irradiation on conidiation in Alternaria tomato. Although near-UV light has the opposite effect on the growth on F. verticillioides (reduced) and A. niger (increased) (Fanelli F., pers.…”

Fungal photoreceptors: sensory molecules for fungal development and behaviour

“…1 Light serves as an environmental signal to regulate fungal development and behaviour, presumably for the optimization of spore production and dispersal ( Table 1). 4 The effect of blue light is often either stimulatory or inhibitory of a developmental transition but the red-light induction of conidiation in A. nidulans can be inhibited by a subsequent exposure to far-red light, and the near-UV induction of conidiation in A. tomato can be inhibited by exposure to blue light, 3,4 suggesting the operation of complex photoreceptor systems. These developmental transitions are regulated by many environmental factors, including the presence or absence of light.…”

PHOTOMORPHOGENESIS IN Phycomyces and IN OTHER FUNGI

“…Departamento de Genttica y Biotecnia, Universidad de Sevilla, Apartado 1095, E-41080 Sevilla, Spain. taneously or in succession and the developmental response will depend on the ratio of near-UV to blue light or on the last wavelength used (Kumagai, 1989). Red light, a promoter of morphogenesis in plants, stimulates the conidiation of Aspergillus nidulans.…”