Lack of Specificity of the Molecular Diagnostic Method for Identification of Aphanomyces Astaci

Species composition of the genus Saprolegnia in fin fish aquaculture environments, as determined by nucleotide sequence analysis of the nuclear rDNA ITS regions

“…Similar challenges were encountered by Oidtmann et al (2004Oidtmann et al ( , 2006 and highlighted by Ballesteros et al (2007), in the design of ITS-based primers for the detection of Aphanomyces astaci, as well as by Schena & Cooke (2006) when attempting to distinguish closely related Phytophthora spp. However, the consistent ITS region nucleotide sequence variability supported existing species designations for Saprolegnia spp, with inter-specific differences exceeding 1.0 % in all cases (Table 2).…”

“…The combination of highly conserved coding regions (18S, 5.8S, and 28S) separated by the variable, non-coding ITS regions has provided a useful resource for taxonomic and phylogenetic studies (Long & Dawid 1980;Richard et al 2008), allowing resolution of many taxa down to the family or genus level (Oditmann et al 2004;Ballesteros et al 2007), especially when morphological traits were incorporated into the analysis (Molina et al 1995;Chen et al 2000Chen et al , 2001Hulvey et al 2007;Johnson et al 2008;Ke et al 2009). Species-level resolution based on nrDNA amplification alone is not always possible (Chen et al 2000(Chen et al , 2001 and may require restriction fragment length polymorphism (RFLP) analysis for the discrimination of closely related taxa (Molina et al 1995).…”

Diseases of crayfish: A review

“…However, Ballesteros et al (2009) showed that these primers lack specificity when used against other species of Aphanomyces isolated from crayfish. Any test used to identify a potential plague outbreak should thus include culture of the pathogen and molecular tools to confirm the presence of A. astaci (Vrålstad et al, 2009).…”

Phylogenetic relationships among plant and animal parasites, and saprotrophs in Aphanomyces (Oomycetes)

“…Identification has been based on host infected due to their restricted host range or type of lesion. The need to identify these economically important pathogens, however, has yielded new characters of taxonomic value such as physiological properties, i.e., constitutive production of chitinase by A. astaci (Unestam, 1966;Andersson and Cerenius, 2002;Ballesteros et al, 2006); the ability to undergo RZE in parasitic Aphanomyces (Cerenius and Söderhäll, 1984Söderhäll, , 1985Royo et al, 2004;Ballesteros et al, 2006); salinity tolerance of A. invadans zoospores (Kiryu et al, 2005), temperature adaptation for some strains of A. astaci (Diéguez-Uribeondo et al, 1995), or molecular detection of A. astaci (Oidtmann et al, 2006;Ballesteros et al, 2007) and A. invadans (Vandersea et al, 2006).…”