Characterisation of populations of Heterodera trifolii Goffart, 1932 (Nematoda: Heteroderidae) in Japan and their phylogenetic relationships with closely related species

Abstract

The Japanese populations of the clover cyst nematode,Heterodera trifolii, were characterised morphologically, morphometrically and molecularly. The morphology and morphometrics of six Japanese populations ofH. trifoliiwere in congruence with those of previous descriptions of this species from Germany, Italy, Japan, New Zealand, Russia, The Netherlands, UK and USA. The results of the phylogenetic analyses of the D2-D3 expansion segments of 28S rRNA gene and theCOImtDNA gene sequences discriminatedH. trifoliifrom most of the other closely related species of theSchachtiigroup. The intraspecific sequence differences in theSchachtiigroup were much higher inCOIthan in D2-D3. TheH. trifoliipopulations displayed very low levels of intraspecific variations (up to 0.3%) in theCOImtDNA gene sequences. The phylogenetic relationships ofH. trifoliiwith otherHeteroderaspecies, as inferred from the analyses of the ITS rRNA gene, D2-D3 of 28S rRNA gene andCOImtDNA gene sequences, were determined.