TY - JOUR
T1 - Ancestral polymorphism and adaptive evolution in the trichothecene mycotoxin gene cluster of phytopathogenic Fusarium
AU - Ward, Todd J.
AU - Bielawski, Joseph P.
AU - Corby Kistler, H.
AU - Sullivan, Eileen
AU - O'Donnell, Kerry
PY - 2002/7/9
Y1 - 2002/7/9
N2 - Filamentous fungi within the Fusarium graminearum species complex (Fg complex) are the primary etiological agents of Fusarium head blight (scab) of wheat and barley. Scab is an economically devastating plant disease that greatly limits grain yield and quality. In addition, scabby grain is often contaminated with trichothecene mycotoxins that act as virulence factors on some hosts, and pose a serious threat to animal health and food safety. Strain-specific differences in trichothecene metabolite profiles (chemotypes) are not well correlated with the Fg complex phylogeny based on genealogical concordance at six single-copy nuclear genes. To examine the basis for this discord between species and toxin evolution, a 19-kb region of the trichothecene gene cluster was sequenced in 39 strains chosen to represent the global genetic diversity of species in the Fg complex and four related species of Fusarium. Phylogenetic analyses demonstrated that polymorphism within these virulence-associated genes is transspecific and appears to have been maintained by balancing selection acting on chemotype differences that originated in the ancestor of this important group of plant pathogens. Chemotype-specific differences in selective constraint and evidence of adaptive evolution within trichothecene genes are also reported.
AB - Filamentous fungi within the Fusarium graminearum species complex (Fg complex) are the primary etiological agents of Fusarium head blight (scab) of wheat and barley. Scab is an economically devastating plant disease that greatly limits grain yield and quality. In addition, scabby grain is often contaminated with trichothecene mycotoxins that act as virulence factors on some hosts, and pose a serious threat to animal health and food safety. Strain-specific differences in trichothecene metabolite profiles (chemotypes) are not well correlated with the Fg complex phylogeny based on genealogical concordance at six single-copy nuclear genes. To examine the basis for this discord between species and toxin evolution, a 19-kb region of the trichothecene gene cluster was sequenced in 39 strains chosen to represent the global genetic diversity of species in the Fg complex and four related species of Fusarium. Phylogenetic analyses demonstrated that polymorphism within these virulence-associated genes is transspecific and appears to have been maintained by balancing selection acting on chemotype differences that originated in the ancestor of this important group of plant pathogens. Chemotype-specific differences in selective constraint and evidence of adaptive evolution within trichothecene genes are also reported.
UR - http://www.scopus.com/inward/record.url?scp=0037047046&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037047046&partnerID=8YFLogxK
U2 - 10.1073/pnas.142307199
DO - 10.1073/pnas.142307199
M3 - Article
C2 - 12080147
AN - SCOPUS:0037047046
SN - 0027-8424
VL - 99
SP - 9278
EP - 9283
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 14
ER -