TY - JOUR
T1 - Hymenoscyphus pseudoalbidus and Hymenoscyphus albidus
T2 - Viridiol concentration and virulence do not correlate
AU - Junker, C.
AU - Mandey, F.
AU - Pais, A.
AU - Ebel, R.
AU - Schulz, B.
N1 - We would like to thank Drs. Simone Bergmann and Christine Boyle for critical review of the manuscript, and two anonymous reviewers and the editor for their constructive criticisms, helping to improve the manuscript. C.J. thanks the Deutsche Bundesstiftung Umwelt for the scholarship that made this research possible. Sponsoring through the ERASMUS programme to A.P. is gratefully acknowledged. F.M. wishes to thank the Indonesian government for a DGHE scholarship. We thank the College of Physical Sciences, University of Aberdeen in the Marine Biodiscovery Centre and the Institute of Microbiology, Technical University of Braunschweig for provision of infrastructure and facilities.
PY - 2014/2/1
Y1 - 2014/2/1
N2 - Hymenoscyphus pseudoalbidus is the causal agent of ash dieback, a disease that is presently endangering Fraxinus spp. throughout most of Europe. The phytotoxin, viridiol, was previously isolated from culture extracts of H. pseudoalbidus and found to be toxic to leaves of F. excelsior. Thus, we were interested in learning to what extent viridiol is responsible for pathogenicity of H. pseudoalbidus and investigated this using twelve isolates of H. pseudoalbidus. We also included five isolates of the closely related avirulent species, Hymenoscyphus albidus, in our studies. Some, but not all, isolates of H. pseudoalbidus and H. albidus produced measurable quantities of viridiol in culture. Three tests were used to determine to what extent viridiol concentration correlates with virulence: culture extracts were tested for activity in leaf segment tests and for inhibition of germination of seedlings of Fraxinus excelsior; virulence of the isolates was tested following infection of axenically cultured ash seedlings. Activity of the culture extracts varied, as did virulence of the isolates following inoculation into seedlings. No correlations were found between viridiol concentration and activities of culture extracts in leaf segment tests or in the germination test, nor between viridiol concentration and disease symptoms when inoculated into seedlings. However, activities of culture extracts in leaf segment and in the germination test correlated, as did the results of each of these tests with virulence in the infection experiment. Apparently, as yet unidentified factors other than the concentration of viridiol play important roles in the virulence of H. pseudoalbidus.
AB - Hymenoscyphus pseudoalbidus is the causal agent of ash dieback, a disease that is presently endangering Fraxinus spp. throughout most of Europe. The phytotoxin, viridiol, was previously isolated from culture extracts of H. pseudoalbidus and found to be toxic to leaves of F. excelsior. Thus, we were interested in learning to what extent viridiol is responsible for pathogenicity of H. pseudoalbidus and investigated this using twelve isolates of H. pseudoalbidus. We also included five isolates of the closely related avirulent species, Hymenoscyphus albidus, in our studies. Some, but not all, isolates of H. pseudoalbidus and H. albidus produced measurable quantities of viridiol in culture. Three tests were used to determine to what extent viridiol concentration correlates with virulence: culture extracts were tested for activity in leaf segment tests and for inhibition of germination of seedlings of Fraxinus excelsior; virulence of the isolates was tested following infection of axenically cultured ash seedlings. Activity of the culture extracts varied, as did virulence of the isolates following inoculation into seedlings. No correlations were found between viridiol concentration and activities of culture extracts in leaf segment tests or in the germination test, nor between viridiol concentration and disease symptoms when inoculated into seedlings. However, activities of culture extracts in leaf segment and in the germination test correlated, as did the results of each of these tests with virulence in the infection experiment. Apparently, as yet unidentified factors other than the concentration of viridiol play important roles in the virulence of H. pseudoalbidus.
UR - http://www.scopus.com/inward/record.url?scp=84893691995&partnerID=8YFLogxK
U2 - 10.1111/efp.12066
DO - 10.1111/efp.12066
M3 - Article
AN - SCOPUS:84893691995
SN - 1437-4781
VL - 44
SP - 39
EP - 44
JO - Forest Pathology
JF - Forest Pathology
IS - 1
ER -