Identification of Heterodera avenae group species by morphometrics and rDNA-RFLPs

Canonical discriminant analysis of four morphometric characters of juvenile s and restriction enzymes analysis of ribosomal DNA sequences were used to distinguish Heterodera arenaria, H. aucklandica, H. avenae, H. filipjevi, H . hordecalis, H. iri, H. latipons, H. litoralis, H. schachtii and an undesc ribed species from grasslands. The results of unweighted pair group cluster analysis showed that H. avenae populations formed three groups and H. fili pjevi two groups at the 80% level of similarity. Intraspecific polymorphism was revealed by rDNA-RFLP studies and two types of ITS regions within H. a venae populations can be distinguished. The pattern of restriction bands ob tained with BsuRI, PstI and TaqI clearly distinguished populations of H. fi lipjevi from other species of the H. avenae group. Further enzymes and thei r combinations distinguished the other species. There are no enzymes which differentiate European populations of H. avenae from H. arenaria. Morphomet rics, restriction endonuclease cleavage maps of ITS regions and a dendrogra m of putative phylogenetic relations of several cyst-forming nematode speci es are given.