New Disease Reports
New Disease Reports (2009) 20, 6.
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First report of the Dutch elm disease pathogens Ophiostoma ulmi and O. novo-ulmi in Japan

H. Masuya 1*, C. Brasier 2, Y. Ichihara 3, T. Kubono 1 and N. Kanzaki 1

*massw@ffpri.affrc.go.jp

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Accepted: 23 Sep 2009

During a survey of Japanese ophiostomatoid fungi in 2007, 91 isolates of the Pesotum anamorph of Ophiostoma were obtained from bark of fallen Ulmus davidiana and U. laciniata trees infested by Scolytus esuriens (Fig. 1) at Akan, Kushiro and Fujimi, Kamikita in Hokkaido .Growth rate, colony morphology and mating tests (Brasier, 1981) together with sequence analyses of the ribosomal ITS region, ceratoulmin (cu) gene and MAT gene DNA, were carried out on selected isolates. On this basis, isolates from both sites were identified as the Dutch elm disease pathogens Ophiostoma ulmi and O. novo-ulmi ssp. americana (Fig. 2). The mean growth rates of five O. ulmi and five O. novo-ulmi isolates at 20°C were 2.36 ± 0.31 and 3.74 ± 0.17 mm/day respectively. The sequences have been deposited at DDBJ (Accession Nos. AB519191 – 6) and isolates deposited at the FFPRI Culture Collection, Tsukuba. 

During the past century O. ulmi and O. novo-ulmi have spread across Europe, North America and central Asia in two separate invasion events, causing highly destructive pandemics. Their geographic origins are unknown. Due to their considerable behavioural differences they have failed to coexist when overlapping, although transient hybrids have emerged (Brasier, 2000).This is the first report of O. ulmi and of O. novo-ulmi in Japan .There have been no previous records of Dutch elm disease in Japan (cf. Heybroek, 1982; Brasier, 1990) and no wilting of elms has been reported in the Hokkaido area. The ‘sudden’ finding of O. ulmi and O. novo-ulmi side by side in beetle breeding galleries therefore requires explanation. One possibility is that O. ulmi is endemic to Japan and O. novo-ulmi ssp. americana is a recent invasive. Genetic and field studies are in progress to assess the status and history of the two pathogens in Japan and their association with the native elms and bark beetles.

Figure1+
Figure 1: Scolytus esuriens associated with Ophiostoma ulmi and O. novo-ulmi in Japan. Scale bar 1 mm.
Figure 1: Scolytus esuriens associated with Ophiostoma ulmi and O. novo-ulmi in Japan. Scale bar 1 mm.
Figure2+
Figure 2: Isolates of Ophiostoma ulmi (above) and O. novo-ulmi ssp. americana (below) from Hokkaido, grown on Oxoid malt extract agar at 20°C for 7 days darkness then diffuse daylight.
Figure 2: Isolates of Ophiostoma ulmi (above) and O. novo-ulmi ssp. americana (below) from Hokkaido, grown on Oxoid malt extract agar at 20°C for 7 days darkness then diffuse daylight.

Acknowledgements

The authors thank Ms Asuka Shichiri and Mr Andrew Jeeves for technical assistance. A part of this study was funded by Global Environment Research Fund of the Ministry of the Environment, Japan (F081).

References

  1. Brasier CM, 1981. Laboratory investigation of Ceratocystis ulmi. In: Stipes RJ, Campana RJ, eds. Compendium of Elm Diseases. St. Paul, USA : APS Press, 76-79.
  2. Brasier CM, 1990. China and the origins of Dutch elm disease: an appraisal. Plant Pathology 39, 5-16.
  3. Brasier CM, 2000.Intercontinental spread and continuing evolution of the Dutch elm disease pathogens. In: Dunn CP, ed. The elms: breeding, conservation, and disease management. Boston : Kluwer Academic Publishers, 61-72.
  4. Heybroek HM, 1982. The Japanese elm species and their value for the Dutch elm breeding programme. In: Kondo ES, Hiratsuka Y, Denyer WGB, eds. Proceedings of the Dutch Elm Disease Symposium and Workshop, Winnipeg, Manitoba October 5-9, 1981, 78-90. Winnipeg, Manitoba, Canada : Manitoba Department of Natural Resources.
This report was formally published in Plant Pathology

©2009 The Authors