Author
 |
Flaherty, Joseph |
|
Dunkle, Larry |
|
Submitted to: Phytopathology
Publication Type: Abstract Only Publication Acceptance Date: 3/15/2004 Publication Date: 5/9/2004 Citation: Flaherty, J.E., Dunkle, L.D. 2004. Blue light represses conidiation in exserohilum turcicum, the causal agent of northern leaf blight of maize. Phytopathology. 94(S):30. Interpretive Summary: Technical Abstract: We examined the effects of light on growth and development of Exserohilum turcicum, the fungal pathogen causing northern leaf blight of maize. Cultures grown under continuous light were developmentally arrested after the formation of conidiophores, whereas cultures maintained in continuous darkness or a light/dark cycle produced mature conidia. Vegetative growth was more extensive under light/dark cycles than under constant light or darkness, both visually and based on ergosterol content. In cultures exposed to various periods of dark before a shift back to continuous light, a 2-hour dark period was sufficient to initiate the conidiation program. Only wavelengths in the blue light range (425-480 nm) repressed conidiation. This light-repressive phenomenon contrasts with other fungal species in which blue light induces or enhances conidiation. Because previous studies have shown that long photoperiods reduce colonization of maize by E. turcicum, we propose that the repressive effect of light on conidiation, growth, and pathogenicity involves signal transduction pathways mediated by a blue-light receptor. The goal of our study is to identify genes involved in light-regulated conidiation and to characterize their involvement in growth, development, and pathogenicity. To this end, we are constructing subtractive cDNA libraries from mRNA isolated from cultures grown under conidiation-permissive and repressive conditions. |
