?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Genetic+structure+and+pathogenicity+of+populations+of+Phytophthora+infestans+from+organic+potato+crops+in+France%2C+Norway%2C+Switzerland+and+the+United+Kingdom&rft.creator=Flier%2C+W.+G.&rft.creator=Kroon%2C+L.+P.+N.+M.&rft.creator=Hermansen%2C+A.&rft.creator=van+Raaij%2C+H.+M.+G.&rft.creator=Speiser%2C+B.&rft.creator=Tamm%2C+L.&rft.creator=Fuchs%2C+J.+G.&rft.creator=Lambion%2C+J.&rft.creator=Razzaghian%2C+J.&rft.creator=Andrivon%2C+D.&rft.creator=Wilcockson%2C+S.&rft.creator=Leifert%2C+C.&rft.subject=Crop+health%2C+quality%2C+protection&rft.subject=+Root+crops&rft.description=Genetic+variation+and+pathogenicity+of+Phytophthora+infestans+isolates+collected+from+organic+potato+crops+of+the+susceptible+cv.+Bintje+and+the+moderately+resistant+cv.+Sant%C3%83%C2%A9+were+assessed+in+France%2C+Norway%2C+and+the+United+Kingdom+in+2001+and+in+Switzerland+in+2001+and+2002.+Population+structures+differed+considerably+between+the+four+P.+infestans+populations.+Those+from+France%2C+Switzerland+and+the+UK+were+mainly+clonal+populations+showing+restricted+levels+of+genetic+diversity%2C+whilst+those+from+Norway+were+mixed+A1+and+A2+mating+type+populations+with+high+levels+of+genetic+diversity%2C+suggesting+periodical+sexual+reproduction.+Isolates+collected+from+cv.+Bintje+were+on+average+more+aggressive+than+or+comparable+to+isolates+from+cv.+Sant%C3%83%C2%A9.+Race+complexity+varied+considerably+between+the+regional+P.+infestans+populations%2C+with+isolates+from+France+and+Switzerland+showing+the+highest+number+of+virulence+factors.+In+all+pathogen+samples+but+the+French%2C+isolates+collected+from+cv.+Sant%C3%83%C2%A9+were+more+complex+than+isolates+collected+from+cv.+Bintje.+No+directional+selection+towards+increased+aggressiveness+towards+the+more+resistant+cultivar+Sant%C3%83%C2%A9+was+observed.+This+suggests+that+there+is+no+shift+towards+increased+levels+of+pathogenicity+in+P.+infestans+populations+following+the+large-scale+introduction+of+more+resistant+potato+varieties+in+organic+production+systems+in+Europe.&rft.date=2007&rft.type=Journal+paper&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Forgprints.org%2F11106%2F1%2Fspeiser-etal-2007-plant_pathology_56.pdf&rft.identifier=Flier%2C+W.+G.%3B+Kroon%2C+L.+P.+N.+M.%3B+Hermansen%2C+A.%3B+van+Raaij%2C+H.+M.+G.%3B+Speiser%2C+B.%3B+Tamm%2C+L.%3B+Fuchs%2C+J.+G.%3B+Lambion%2C+J.%3B+Razzaghian%2C+J.%3B+Andrivon%2C+D.%3B+Wilcockson%2C+S.+and+Leifert%2C+C.+(2007)+Genetic+structure+and+pathogenicity+of+populations+of+Phytophthora+infestans+from+organic+potato+crops+in+France%2C+Norway%2C+Switzerland+and+the+United+Kingdom.+Plant+Pathology%2C+56%2C+pp.+562-572.&rft.relation=http%3A%2F%2Forgprints.org%2F11106%2F