Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 29, 2012
Publication Date: March 1, 2012
Citation: Skantar, A.M., Handoo, Z.A., Zanakis, G.N., Tzortzakakis, E.A. 2012. Molecular and morphological characterization of the corn cyst nematode, Heterodera zeae, from Greece. Journal of Nematology. 44(1):58-66. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack plant roots and cause an estimated ten billion dollars of crop loss each year in the United States and 100 billion dollars globally. Cyst nematodes are an important group of nematodes that damage the roots of many kinds of plants throughout the world. Some cyst nematodes infect corn, a crop of major importance for human consumption, as feed for livestock, and as a source of bioenergy. In this study, a team of ARS scientists and colleagues from Greece analyzed anatomical and molecular traits to identify the corn cyst nematode isolated from a cornfield in Greece, the first report of this nematode from that country. This discovery is significant because new molecular information obtained for this population will facilitate future identification of corn cyst nematode. This report will serve as a useful guide to researchers and diagnosticians identifying economically important cyst nematodes of corn.
Technical Abstract: The corn cyst nematode Heterodera zeae was first detected in India, where it has wide distribution. This nematode has also been reported from Pakistan, Egypt, Thailand, Nepal, the United States, and Portugal. There is limited information regarding nematodes attacking cereals in Greece, and thus far the only cyst nematode reported there has been H. avenae on wheat. In May 2009, a soil sample containing abundant cysts was taken from an organic maize field in northern Greece; the field was under winter fallow at the time of sampling. Soil from the field site was used to inoculate maize plants (Zea mays) grown in a greenhouse. Females appeared after six weeks incubation, and abundant cysts were present after 12 weeks. Morphological and molecular diagnosis confirmed the presence of H. zeae. Amplification of ribosomal DNA (rDNA) markers included the internal transcribed spacer region (ITS1 - 5.8S- ITS2), 28S large subunit (LSU) D2-D3 expansion segment, and partial 18S small subunit (SSU). PCR-RFLP of ITS rDNA exhibited several unique enzyme patterns that may be diagnostically useful for H. zeae. These findings are in agreement with prior analysis of H. zeae populations from the U.S. and India. Phylogenetic relationships inferred from ITS rDNA agreed with earlier trees that placed H. zeae in a clade with H. turcomanica, H. salixophila and species of the Humuli group. Phylogenetic trees based upon Hsp90 coding sequence were in general agreement with a prior study using the same marker. This study represents the first record of H. zeae in Greece and the second report of this nematode in Europe.