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Potential for fingerprinting.
The resolutive power of the sequenced region was comparable to other molecular tools
used for B. bassiana fingerprinting. A sample of 96 isolates was separated into 24
genotypes when Coates et al., (2002) performed PCR-RFLP on it, a level of resolution
close to the 20 genotypes found in our 97 isolates set. Culture methods like vegetative
compatibility grouping also have shown high polymorfism in this fungus (Castrillo et al.,
2004; Couteaudier and Viaud, 1997), but they are more time and labour-consuming than
sequencing.
Both anonymous DNA (RAPD, Bidochka et al., 1994; Maurer et al 1997; Castrillo et al.,
2003; minisatellite, Coates et al., 2001) and non anonymous DNA (ITS region, Aquino de
Muro et al., 2003; Neuveglise et al., 1994, 1997; Glare and Inwood, 1998; 28s rDNA
region, Wang et al 2002; telomere, Couteaudier and Viaud, 1997; nuclear small subunit
rRNA (nuSSU rRNA) introns, Coates et al., 2002b) have been targeted for fingerprintig.
When a global B. bassiana sample was assessed, the ITS region was less variable than the
gene elongation factor 1 alpha EF1-α (Rehner and Buckley, 2005) and the B fragment has
shown to be more variant than EF1-α (Rehner, unpubl. data).
Castrillo et al., (2003) developed SCAR markers from unique RAPD bands, which were
able to distinguish one isolate of particular interest from other indigenous B. bassiana. This
method has great potential because was useful to detect minute amount of target DNA
directly from soil, but it can not be applied to several isolates simultanously. In this case,
SCARs for each single isolate must be designed. The B fragment sequencing do detect
several isolates at the same time, although with a relatively lower power resolution than
multiple SCARs.
Conclusions.
The survey of B fragment variation within and among populations of B. bassiana
throughout a large part of its geographical range in Chile has showed that many genotypes
exist into the species. The phylogenetic analysis yielded weak evidence for a correlation
between genetic variation and geographical origin. However, population structure tests
such as AMOVA and genetic distance pairwise comparisons of putative populations
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