This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Peever, T. L.
Right arrow Articles by Milgroom, M. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Peever, T. L.
Right arrow Articles by Milgroom, M. G.
Agricola
Right arrow Articles by Peever, T. L.
Right arrow Articles by Milgroom, M. G.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, November 2000, p. 4863-4869, Vol. 66, No. 11
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Variation in Tolerance and Virulence in the Chestnut Blight Fungus-Hypovirus Interaction

Tobin L. Peever,1,dagger Yir-Chung Liu,1 Paolo Cortesi,2 and Michael G. Milgroom1,*

Department of Plant Pathology, Cornell University, Ithaca, New York,1 and Istituto di Patalogia Vegetale, Università degli Studi di Milano, Milan 20133, Italy2

Received 6 March 2000/Accepted 29 August 2000

Chestnut blight, caused by the fungus Cryphonectria parasitica, has been effectively controlled with double-stranded RNA hypoviruses in Europe for over 40 years. The marked reduction in the virulence of C. parasitica by hypoviruses is a phenomenon known as hypovirulence. This virus-fungus pathosystem has become a model system for the study of biological control of fungi with viruses. We studied variation in tolerance to hypoviruses in fungal hosts and variation in virulence among virus isolates from a local population in Italy. Tolerance is defined as the relative fitness of a fungal individual when infected with hypoviruses (compared to being uninfected); virulence is defined for each hypovirus as the reduction in fitness of fungal hosts relative to virus-free hosts. Six hypovirus-infected isolates of C. parasitica were sampled from the population, and each hypovirus was transferred into six hypovirus-free recipient isolates. The resulting 36 hypovirus-fungus combinations were used to estimate genetic variation in tolerance to hypoviruses, in hypovirus virulence, and in virus-fungus interactions. Four phenotypes were evaluated for each virus-fungus combination to estimate relative fitness: (i) sporulation, i.e., the number of asexual spores (conidia) produced; (ii) canker area on field-inoculated chestnut trees, (iii) vertical transmission of hypoviruses into conidia, and (iv) conidial germination. Two-way analysis of variance (ANOVA) revealed significant interactions (P < 0.001) between viruses and fungal isolates for sporulation and canker area but not for conidial germination or transmission. One-way ANOVA among hypoviruses (within each fungal isolate) and among fungal isolates (within each hypovirus) revealed significant genetic variation (P < 0.01) in hypovirus virulence and fungal tolerance within several fungal isolates, and hypoviruses, respectively. These interactions and the significant genetic variation in several fitness characters indicate the potential for future evolution of these characters. However, biological control is unlikely to break down due to evolution of tolerance to hypoviruses in the fungus because the magnitudes of tolerance and interactions were relatively small.

* Corresponding author. Mailing address: Department of Plant Pathology, Cornell University, Ithaca, NY 14853-4203. Phone: (607) 255-7872. Fax: (607) 255-4471. E-mail: mgm5{at}cornell.edu.

dagger Present address: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430.

Applied and Environmental Microbiology, November 2000, p. 4863-4869, Vol. 66, No. 11
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:

  • Salvaudon, L., Heraudet, V., Shykoff, J. A (2008). Arabidopsis thaliana and the Robin Hood parasite: a chivalrous oomycete that steals fitness from fecund hosts and benefits the poorest one?. Biol Lett 4: 526-529 [Abstract] [Full Text]  
  • Carbone, I., Liu, Y.-C., Hillman, B. I., Milgroom, M. G. (2004). Recombination and Migration of Cryphonectria hypovirus 1 as Inferred From Gene Genealogies and the Coalescent. Genetics 166: 1611-1629 [Abstract] [Full Text]  
  • Suzuki, N., Maruyama, K., Moriyama, M., Nuss, D. L. (2003). Hypovirus Papain-Like Protease p29 Functions in trans To Enhance Viral Double-Stranded RNA Accumulation and Vertical Transmission. J. Virol. 77: 11697-11707 [Abstract] [Full Text]  
  • Cortesi, P., McCulloch, C. E., Song, H., Lin, H., Milgroom, M. G. (2001). Genetic Control of Horizontal Virus Transmission in the Chestnut Blight Fungus, Cryphonectria parasitica. Genetics 159: 107-118 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»