Is Phytophthora kernoviae a mutation of Phytophthora ramorum?
P. kernoviae was initially discovered in Cornwall, a county known to have higher than average levels of natural radioactivity (due to the presence of radon natural gas in uranium-bearing granite rocks.) This has led to the suggestion that these naturally occurring levels of radioactivity have caused P. ramorum to mutate, giving rise to P. kernoviae. However, if P. kernoviae were to be a mutant of P. ramorum then we would expect the two species to be similar in morphology and DNA sequence. This is not the case and there are, indeed, marked differences. It appears that P. kernoviae is more closely related to other Phytophthora species (e.g. P. boehmeriae) in a group of Phytopthora species which are relatively distantly related to the main Phytopthora groups that contain P. ramorum. Genetic analysis of P. kernoviae isolates has provided evidence that it is a recently introduced pathogen since the amount of genetic variation in the pathogen population is small.
