EPPO Global Database

EPPO Reporting Service no. 04 - 1994 Num. article: 1994/65

Genetic relatedness between elm phloem necrosis MLO and strains of elm yellows MLO from Italy

Experiments were carried out in the USA (US) in order to compare the relatedness of strains of elm phloem necrosis MLO (EPPO A1 quarantine pest) from the US and MLO strains from Italy (IT) causing a yellows disease on Ulmus spp. Nucleic acid dot hybridization was applied to study the genetic relatedness and it was found that American strains from Ulmus americana and Italian strains from U. parvifolia are closely related. The data suggests the existence of a unique elm yellows MLO strain cluster which is only distantly related to the aster yellows MLO strain cluster. First experiments in using PCR for the detection of elm phloem necrosis revealed the presence of various strains of the MLO in North America that were distinct from a strain of elm yellows MLO present in Italy.


Lee, I.-M.; Davis, R.E.; Sinclair, W.A.; DeWitt, N.D.; Conti, M. (1993) genetic relatedness of mycoplasma-like organisms detected in Ulmus spp. in the United States and Italy by means of DNA probes and polymerase chain reactions.
Phytopathology 83, 829-833