title: The role of Cercospora zeae-maydis homologs of Rhodobacter sphaeroides 1O2-resistance genes in resistance to the photoactivated toxin cercosporin.
abstract: The photosynthetic bacterium Rhodobacter sphaeroides and plant pathogenic fungus Cercospora nicotianae have been used as models for understanding resistance to singlet oxygen ((1)O(2)), a highly toxic reactive oxygen species. In Rhodobacter and Cercospora, (1)O(2) is derived, respectively, from photosynthesis and from the (1)O(2)-generating toxin cercosporin which the fungus produces to parasitize plants. We identified common genes recovered in transcriptome studies of putative (1)O(2)-resistance genes in these two systems, suggesting common (1)O(2)-resistance mechanisms. To determine if the Cercospora homologs of R. sphaeroides (1)O(2)-resistance genes are involved in resistance to cercosporin, we expressed the genes in the cercosporin-sensitive fungus Neurospora crassa and assayed for increases in cercosporin resistance. Neurospora crassa transformants expressing genes encoding aldo/keto reductase, succinyl-CoA ligase, O-acetylhomoserine (thiol) lyase, peptide methionine sulphoxide reductase and glutathione S-transferase did not have elevated levels of cercosporin resistance. Several transformants expressing aldehyde dehydrogenase were significantly more resistant to cercosporin. Expression of the transgene and enzyme activity did not correlate with resistance, however. We conclude that although the genes tested in this study are important in (1)O(2) resistance in R. sphaeroides, their Cercospora homologs are not involved in resistance to (1)O(2) generated from cercosporin.
authors: Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA.
authors: Aydin
authors: A
authors: Beseli
authors: Phytopathology Department; Federal University of Lavras, Lavras, MG, 37200-000, Brazil.
authors: Marilia
authors: M
authors: Goulart da Silva
authors: Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA margaret_daub@ncsu.edu.
authors: Margaret E
authors: ME
authors: Daub
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism; D001203:Ascomycota / Q000235:genetics*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D003904:Mitosporic Fungi / Q000235:genetics*; D009492:Neurospora crassa / Q000235:genetics; D016877:Oxidants; D010569:Perylene / Q000031:analogs & derivatives* / Q000494:pharmacology; D060888:Real-Time Polymerase Chain Reaction; D012242:Rhodobacter sphaeroides / Q000235:genetics* / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism; D059467:Transcriptome
chemical_list: D016877:Oxidants; D026082:Singlet Oxygen; D010569:Perylene; C026363:cercosporin; D000444:Aldehyde Dehydrogenase; D005982:Glutathione Transferase
keywords: Cercospora; O-acetylhomoserine (thiol) lyase; Rhodobacter; aldehyde dehydrogenase; aldo/keto reductase; cercosporin; glutathione S-transferase; peptide methionine sulphoxide reductase; singlet oxygen; succinyl-CoA ligase