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Characterization of Blue‐light and Developmental Regulation of the Photolyase gene phr1 in Trichoderma harzianum
Author(s) -
BerrocalTito Gloria M.,
RosalesSaavedra Teresa,
HerreraEstrella Alfredo,
Horwitz Benjamin A.
Publication year - 2000
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2000)0710662coblad2.0.co2
Subject(s) - photolyase , biology , trichoderma harzianum , conidiation , microbiology and biotechnology , spore , phytochrome , cryptochrome , phototropism , ultraviolet light , gene , dna repair , mutant , botany , blue light , genetics , chemistry , circadian clock , red light , physics , biological pest control , optics , photochemistry
Blue light and development regulate the expression of the phr1 gene of the filamentous fungus Trichoderma harzianum. The predicted product of phr1 , the DNA repair enzyme photolyase, is likely to help protect Trichoderma , which grows in the soil as a mycoparasite or saprophyte, from damage upon emergence and exposure to ultraviolet‐c. phr1 is transiently expressed in mycelium and conidiophores after illumination. phr1 mRNA also accumulates in conidiophores during development and spore maturation. As no other genes displaying rapid, direct light regulation have been described previously in this organism, we have characterized the fluence and time dependence of phr1 induction, and its relation to sporulation and photoreactivation. Induction is transient following a pulse, and, with slower decay, in continuous light. This implies that the photoreceptor, transducers or response are capable of adaptation. About two‐fold more light is required to induce phr1 than conidiation, but this difference is modest, so both responses could use the same or similar chromophore. Adenosine 3′:5′‐cyclic monophosphate bypasses the requirement for light for sporulation, while atropine prevents sporulation even after photoinduction. Light regulation of phr1 , however, is indifferent to both these effectors. Induction of photolyase expression behaves as a direct, rapid response to light, independent of the induction of sporulation. Indeed, illumination of mature spores increases their capacity for photoreactivation. Blue light seems to warn the organism against the harmful effects of short wavelengths, inducing phr1 expression and sporulation by pathways that are, at least in part, distinct.