RESULTS AND DISCUSSION
The protocol described was found to be suitable for the
extraction of genomic DNA from minute quantities of
mycorrhizal samples. The DNA yield was approximately
2 and 5 ng ll
±1 with the endo- and ecto-mycorrhizal fungi,
respectively. Use of the QIAquick columns (Qiagen Ltd,
Crawley, West Sussex, UK), according to the manufacturer's
instructions, is expected to yield puri®ed DNA
fragments up to 40 kb in size. Each extraction provided
template DNA suf®cient for 10±15 ampli®cation reactions
(50 ll volume). The DNA was successfully used to PCR
amplify speci®c fragments (from 650 bp to more than
2000 bp) from nearly 40 isolates representing a number of
ecto- and endo- mycorrhizal species (Table 1 and Fig. 1).
Successful ampli®cation was achieved not only with the high
copy ribosomal RNA gene block, but also the low or single
copy chitin synthase gene(s). The amplicons were used to
generate sequence data for the ITS region in more than
20 isolates (data not shown). Amplicon yield from a 50 ll
reaction was suf®cient to perform at least 2±4 sequencing
reactions, using the ABI Prism automated sequencing
technology.