title: Growth under visible light increases conidia and mucilage production and tolerance to UV-B radiation in the plant pathogenic fungus Colletotrichum acutatum.
abstract: Light conditions can influence fungal development. Some spectral wavebands can induce conidial production, whereas others can kill the conidia, reducing the population size and limiting dispersal. The plant pathogenic fungus Colletotrichum acutatum causes anthracnose in several crops. During the asexual stage on the host plant, Colletototrichum produces acervuli with abundant mucilage-embedded conidia. These conidia are responsible for fungal dispersal and host infection. This study examined the effect of visible light during C. acutatum growth on the production of conidia and mucilage and also on the UV tolerance of these conidia. Conidial tolerance to an environmentally realistic UV irradiance was determined both in conidia surrounded by mucilage on sporulating colonies and in conidial suspension. Exposures to visible light during fungal growth increased production of conidia and mucilage as well as conidial tolerance to UV. Colonies exposed to light produced 1.7 times more conidia than colonies grown in continuous darkness. The UV tolerances of conidia produced under light were at least two times higher than conidia produced in the dark. Conidia embedded in the mucilage on sporulating colonies were more tolerant of UV than conidia in suspension that were washed free of mucilage. Conidial tolerance to UV radiation varied among five selected isolates.
authors.affiliation: Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
authors.forename: Henrique D
authors.initials: HD
authors.lastname: de Menezes
authors.forename: Nelson S
authors.initials: NS
authors.lastname: Massola
authors.forename: Stephan D
authors.initials: SD
authors.lastname: Flint
authors.forename: Geraldo J
authors.initials: GJ
authors.lastname: Silva
authors.forename: Luciano
authors.initials: L
authors.lastname: Bachmann
authors.forename: Drauzio E N
authors.initials: DE
authors.lastname: Rangel
authors.forename: Gilberto U L
authors.initials: GU
authors.lastname: Braga
mesh_terms: D000222:Adaptation, Physiological; D002957:Citrus / Q000382:microbiology; D020231:Colletotrichum / Q000502:physiology / Q000528:radiation effects*; D062610:Fungal Polysaccharides / Q000819:agonists* / Q000096:biosynthesis; D017440:Photoperiod; D011836:Radiation Tolerance; D013172:Spores, Fungal / Q000502:physiology / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D062610:Fungal Polysaccharides