sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDU Faculty of Forestry Journal
Serial: A, Number: Special Issue, Year: 2009, ISSN: 1302-7085, Page: 233-237
CHARACTERISATION OF CZECH Ophiostoma novo-ulmi ISOLATES
Milon DVOŘÁK 1* , Libor JANKOVSKÝ 1 , J . KRAJŇÁKOVÁ 2
1 Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood
Technology, Mendel University of Agriculture and Forestry, Brno, Zemedelska 3, 613 00 Brno,
Czech Republic
2 Department of Biology and Plant Protection, Unit of Plant Biology, University of Udine, Via
Cotonificio 108, 33100 Udine, Italy
ABSTRACT
* klobrc@centrum.cz
Ophiostoma novo-ulmi was recorded for the first time in the area of the Czech Republic
in 2006, although it was suspected since early 1960´s. During the years 2006 and 2007, 58
isolates were collected. Isolated strains of the DED causal agent were determined by PCR
and RFLP molecular methods. DNA of each sample was isolated from cultured mycelium,
amplified at cu, and col1 gene regions and restricted by Hph I and Bfa I endonucleases.
Strains were determined according to both of these two gene regions. An old species
Ophiostoma ulmi (Buism.) Nannf. was not noticed in any case. Every sample belongs to the
species Ophiostoma novo-ulmi Bras., and both known subspecies americana (5 isolates)
and novo-ulmi (29 isolates) were present. Additionally, 13 strains of Ophiostoma novo-ulmi
were more particularly tested for vegetative compatibility type, mating type, fertility with
both subspecies and cerato-ulmin production. Among these 13 strains only 3 seemed to be
non-hybridized ssp. novo-ulmi and only one non-hybridized ssp. americana, the remainder
(9 strains) was intraspecific hybrids. 5 of the tested strains were of mating type A and
mating type B occurred 8-times. None of these strains was compatible with any other. High
frequency of intraspecific hybrids (24 isolates) is remarkable and shows on a frequent
occurrence of sexual hybridization. Cerato-ulmin production did not show any significant
differences according to strain subspecies. Virulence of one O. novo-ulmi strain (M3) was
tested on two Dutch resistant cultivars, 13-year-old elms ´Groeneveld´ and ´Dodoens´. Only
5 weeks after inoculation were sufficient period for 30 – 90% defoliation of cultivar
´Groeneveld´, ´Dodoens´ with only 0 – 5% seemed to be much more resistant.
Keywords: Dutch Elm Disease, PCR-RFLP, elm, infection tests
1. INTRODUCTION
Ophiostoma ulmi and O. novo-ulmi – causal agents of Dutch elm disease (DED)
has been threatening elms in the Czech Republic since 1930's, as well as in the
entire Northern Hemisphere. The first occurrence of Dutch elm disease in the
Czech Republic caused by Ophiostoma ulmi (Buism.) Nannf. was noted by prof.
Peklo (Polák, 1932) who found infected trees in elm alleys in Prague and
Poděbrady in 1932.
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