Geographic variation of Chondrostereum purpureum detected by polymorphisms in the ribosomal DNA

Abstract

Variation in the ribosomal (rDNA) repeat was analyzed for 107 isolates of the pathogenic fungus Chondrostereum purpureum, collected from Europe, New Zealand, and North America. The rDNA repeat of a representative Canadian isolate of C. purpureum was cloned into the λ vector EMBL-3, and a detailed restriction map was constructed. Variation in the large non-transcribed spacer region of the rDNA was determined for the entire collection of isolates following amplification by the polymerase chain reaction (PCR) and analysis of restriction fragment length polymorphisms (RFLPs). Three distinct nuclear type patterns were identified using the restriction endonuclease HaeIII. Nuclear type I was found in North American, European, and New Zealand isolates. Nuclear type II was only detected in isolates collected from North America, and nuclear type III was observed in isolates collected from both Europe and New Zealand. Nuclear type I was the predominant nuclear type in eastern North America as indicated by a frequency of 0.78, and nuclear type II occurred with a frequency of 0.89 in western North America. Gene flow across the continent was indicated by nearly equal nuclear type distributions (nuclear type I, 0.41; nuclear type II, 0.59) in central North America, but geographic separation has led to unequal nuclear-type distributions across North America. Keywords: Chondrostereum purpureum, biological control, genetic variation, ribosomal DNA.

Variation in the mitochondrial DNA of the potential biological control agent Chondrostereum purpureum

“…Isolate collection and storage conditions were as described by Ramsfield et al (1996). A total of 84 isolates (Table 1) were grown in 250 mL of 1.25% malt extract broth (Difco, Detroit, Mich.) at 125 rpm at 22°C for 3-4 weeks under a 10 h light : 14 h dark photoperiod.…”

“…Mycelium was harvested by vacuum filtration, frozen at -86°C, and freeze-dried. Total DNA was extracted from 2-5 g of freeze-dried mycelium according to Ramsfield et al (1996) but scaled up to account for the larger volume of freeze-dried mycelium.…”

Chondrostereum purpureumandFusarium tumidumindependently reduce regrowth in gorse (Ulex europaeus)

“…In Canada, molecular studies showed that genetic exchange occurs freely across Canada and that there is little risk that a mycoherbicide isolate would introduce rare alleles to a local population of C. purpureum (Ramsfield et al 1996). Similarly in New Zealand, C. purpureum is genetically highly diverse with no host species or locality specialisation (Spiers et al 2000), indicating that a single isolate could also be used throughout New Zealand.…”

A retrotransposon-like element and its occurrence in British Columbia populations of Chondrostereum purpureum

“…The previous studies of Ramsfield et al (1996Ramsfield et al ( ,1999 had evaluated the genetic variability of C. purpureum isolates collected from populations in North America, Europe, and New Zealand, with the aid of nuclear and mitochondrial DNA genetic markers. These markers detected a low level of genetic variability among isolates over a large geographical area, suggesting few barriers to gene flow.…”

“…Our conclusions are in agreement with the findings of previous population studies conducted over larger geographical areas. These studies evaluated the genetic variability of C. purpureum in North America, Europe, and New Zealand using nuclear and mitochondrial DNA markers (Ramsfield et al, 1996(Ramsfield et al, , 1999, within Canada using protein patterns (Ekramoddoullah et al, 1993) and within eastern Canada using RAPD loci (Gosselin et al, 1999a,b).…”