Molecular and Morphological Characterization of the Corn Cyst Nematode, Heterodera zeae, from Greece

摘要

The corn cyst nematode Heterodera zeae was detected in soil from an organic maize ?eld in northern Greece.In greenhouse studies, reproduction of H.zeae was detected on maize plants (Zeae mays) using soil high in organic matter; the ?eld was under winter fallow at the time of sampling.Maize plants were grown in a greenhouse with soil from the affected ?eld used as inoculum.Females appeared after six weeks incubation, and abundant cysts were present after 12 weeks.Morphological and molecular diagnosis con?rmed the presence of H.zeae in the ?eld.Cysts were identi?ed on the basis of cyst shape and characteristics of the cyst terminal cone, including nature of fenestration, presence of bullae, cyst wall pattern, and fenestral diameter.Second-stage juveniles were identi?ed by body and stylet length, the shape of stylet knobs, shape and length of the tail and hyaline tail terminus, and by the number of lateral lines.Molecular analysis included ampli?cation of the ribosomal internal transcribed spacer regions (ITS 1&2 rDNA) 28S large ribosomal subunit (LSU) D2-D3 expansion segment, and partial 18S small ribosomal subunit (SSU).Restriction fragment length polymorphism (RFLP) of ITS rDNA exhibited several unique enzyme patterns that may be diagnostically useful for H.zeae.These?ndingsarein agreementwithprioranalysisof H.zeaepopulationsfromtheU.S.andIndia.Phylogeneticrelationships inferred from ITS rDNA are congruent with previous analyses that placed H.zeae in a clade with H.turcomanica, H.salixophila and speciesof the Humuli group.Phylogenetic treesbaseduponheat shockprotein(Hsp90)codingsequencewere in generalagreement with a prior study using the same marker.This study represents the ?rst record of H.zeae in Greece and the second report of this nematode in Europe.