Send to

Choose Destination
See comment in PubMed Commons below
Phytopathology. 1999 Sep;89(9):754-60. doi: 10.1094/PHYTO.1999.89.9.754.

Multiple Loci Determining Insensitivity to Phenylamide Fungicides in Phytophthora infestans.


The diversity of mechanisms causing insensitivity to phenylamide fungicides in Phytophthora infestans was addressed by comparative genetic analyses of isolates from North America, Europe, and Mexico. Both semidominant major loci (MEX loci) and genes of minor effect were previously shown to determine insensitivity based on studies of isolates from Europe and Mexico. In this investigation, genetic analyses of three highly insensitive isolates from the United States and Canada revealed a similar pattern involving major and minor loci. However, MEX alleles in two Canadian isolates conferred higher levels of insensitivity than those examined previously, particularly in a heterozygous state. This suggested that not all MEX alleles in P. infestans were functionally equivalent. The chromosomal locations of the major insensitivity loci were also shown to vary in different isolates based on linkage analyses performed with the aid of DNA markers. The major determinant of insensitivity in the North American, Dutch, and Mexican isolates mapped to the same locus, which was named MEX1. In a British isolate, a different locus, dubbed MEX2, was implicated that mapped to the same linkage group as MEX1 but to a distinct site.

Free full text
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Atypon
    Loading ...
    Support Center