Early expression of aflatoxin-like dothistromin genes in the forest pathogen Dothistroma septosporum.
The forest pathogen Dothistroma septosporum produces the polyketide dothistromin, a mycotoxin very similar in structure to versicolorin B, a precursor of aflatoxin (AF). Dothistromin is a broad-range toxin and possibly involved in red-band needle blight disease. As the role of dothistromin in the disease is unknown the expression of dothistromin genes was studied to reveal clues to its function. Although the genes of AF and dothistromin biosynthesis are very similar, this study revealed remarkable differences in the timing of their expression. Secondary metabolites, like AF, are usually produced during late exponential phase. Previously identified dothistromin genes, as well as a newly reported versicolorin B synthase gene, vbsA, showed high levels of expression during the onset of exponential growth. This unusual early expression was also seen in transformants containing a green fluorescent protein (GFP) gene regulated by a dothistromin gene promoter, where the highest GFP expression occurred in young mycelium. Two hypotheses for the biological role of dothistromin are proposed based on these results. The study of dothistromin genes will improve current knowledge about secondary metabolite genes, their putative biological roles, and their regulation.
Schwelm
Arne
A
National Centre for Advanced Bio-Protection Technologies, Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Barron
Naydene J
NJ
Zhang
Shuguang
S
Bradshaw
Rosie E
RE
D000880:Anthraquinones / Q000378:metabolism*; D001203:Ascomycota / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009183:Mycotoxins / Q000235:genetics / Q000378:metabolism*; D009520:New Zealand; D028223:Pinus / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013172:Spores, Fungal / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D000880:Anthraquinones; D009183:Mycotoxins; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C042735:dothistromin