Transformation-mediated complementation of a FUM gene cluster deletion in Fusarium verticillioides restores both fumonisin production and pathogenicity on maize seedlings.
The filamentous ascomycete Fusarium verticillioides is a pathogen of maize and produces the fumonisin mycotoxins. However, a distinct population of F. verticillioides is pathogenic on banana and does not produce fumonisins. Fumonisin-producing strains from maize cause leaf lesions, developmental abnormalities, stunting, and sometimes death of maize seedlings, whereas fumonisin-nonproducing banana strains do not. A Southern analysis of banana strains did not detect genes in the fumonisin biosynthetic gene (FUM) cluster but did detect genes flanking the cluster. Nucleotide sequence analysis of the genomic region carrying the flanking genes revealed that the FUM cluster was absent in banana strains except for portions of FUM21 and FUM19, which are the terminal genes at each end of the cluster. Polymerase chain reaction analysis confirmed the absence of the cluster in all banana strains examined. Cotransformation of a banana strain with two overlapping cosmids, which together contain the entire FUM cluster, yielded fumonisin-producing transformants that were pathogenic on maize seedlings. Conversely, maize strains that possess the FUM cluster but do not produce fumonisins because of mutations in FUM1, a polyketide synthase gene, were not pathogenic on maize seedlings. Together, the data indicate that fumonisin production may have been lost by deletion of the FUM cluster in the banana population of F. verticillioides but that fumonisin production could be restored by molecular genetic complementation. The results also indicate that fumonisin production by F. verticillioides is required for development of foliar disease symptoms on maize seedlings.
United States Department of Agriculture-Agricultural Research Service, Russell Research Center, Toxicology & Mycotoxin Research Unit, Athens, GA 30605, USA. anthony.glenn@ars.usda.gov
Anthony E
AE
Glenn
Nicholas C
NC
Zitomer
Anne Marie
AM
Zimeri
Lonnie D
LD
Williams
Ronald T
RT
Riley
Robert H
RH
Proctor
D001483:Base Sequence; D015139:Blotting, Southern; D037341:Fumonisins / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics* / Q000472:pathogenicity*; D017353:Gene Deletion; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D028521:Musa / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D036226:Seedlings / Q000382:microbiology*; D014170:Transformation, Genetic; D003313:Zea mays / Q000382:microbiology*
D037341:Fumonisins