Joint research project

Assessment of the health status of chestnut trees (Castanea sativa Mill) in Azerbaijan: Focus on chestnut blight and associated fungal diseases.

Project leaders
Biancaelena Maserti, Dilzara Aghayeva
AZERBAIJAN - ANAS - Azerbaijan National Academy of Sciences
CNR-ANAS 2016-2017
Biology, agriculture and food sciences
Thematic area
Biology, agriculture and food sciences
Status of the project
Report for renewal

Research proposal

Present state of knowledge in the field, significance and objectives of the joint research:
The Asian fungus Cryphonectria parasitica is mainly found on members of the Fagaceae and well known as the chestnut blight fungus (Adamíková et al. 2010). The fungus forms a canker and attacks the stem and branches of chestnut, progressively weakening the tree and resulting in death of branches or entire tree. In the past, this fungus had a great impact on the European chestnut (Castanea sativa Mill.) and on the American chestnut (Castanea dentata (Marsh.) Borkh.) completely devastating American chestnut forests.Hypovirulent strains of the fungus occur in nature due to infection of the fungus with a double-stranded RNA virus and they are used for a natural disease control. The application of a hypovirulent strain around developing lesions may enable these lesions to recover and can convert the virulent strain into a hypovirulent strain. The method is widely applied in many European countries. Hypovirus has a cytoplasmatic origin and the transmission of hypovirulence from strain to strain of the fungus is restricted by a genetic system of vegetative compatibility. Many vegetative compatibility (vc) types have been recorded in Europe (Bissegger et al., 1997; Robin et al. 2000). Knowledge of the vc types and their geographic distribution in an area are crucial for successful application of biological control (Anagnostakis et al. 1986; Heiniger, Rigling 1994). Many reports (Mayer, 1987; Rigling, Heiniger, Hohl 1989; Rigling, Alfen 1991; 1993) suggested that transmissible hypovirulence may be associated with laccase production in the fungus as it was reported that laccase production is reduced in hypovirulent strains of C. parasitica containing the European type of dsRNA. However the biological function of laccase in the virulence of C. parasitica is not clarified and could be also exert its function together with other enzymes such those of the glyoxylate cycle that have been found to be involved in the virulence of Candida (Lorenz and Fink 2001). Additionally many pathogen fungi produce large amount of cell-wall degrading enzyme such as pectinase, cellulose, protease and glucanase helping them to penetrate and invading the host cells.

Azerbaijan chestnuts (C. sativa) grow in mixed forests together with oak, beech, hornbeam and is actively cultivating by the population living along the west part of Great Caucasus mountain. Chestnut cultivation is one of the main activities of these populations and the main life source for these regions (Wall, Aghayeva 2013).
Since 2003, there have been reports of sweet chestnut mortality from Azerbaijan (Aghayeva, and Harrington 2008). Upon field inspection in 2004, symptoms on the dead and dying trees included crown dieback and cankers on the main stem with yellow to orange, sometimes reddish, fungal stromata. The fungus was identified based on morphology and molecular approach, two representative sequences were deposited into NCBI as Acc. Nos. EF545114 and EF545115 (Aghayeva and Harrington 2008). But the structure of the population, vc types, genetic variability and potential virulence enzyme production have not been studied yet.

Background of cooperation and envisaged results and benefit:
In the past 200yrs, the number of fungal and fungal-like Invasive Alien Species (IAS) challenging plants in Europe has increased exponentially, especially in regards to ascomycetes Santini et al. (2013). Most of them (57%) have been introduced to Europe through living plants and have caused serious epidemics. The recent outbreak of ash dieback in Central Europe and the UK, the spread of pitch canker of pine in plantations in Spain (Brown and Brasier 2013) challenging both plantations and natural forests is only a recent example of new threats to be added to 'old' invasions still threatening European forests. The proposed research will clarify the health status of Azerbaijan chestnuts providing quantitative information about the epidemics of fungal disease in chestnuts and in particular of the chestnut blight disease in Azerbaijan.The work outlined in the proposal will be crucial for designing an effective biological control treatment for Azerbaijan chestnuts and the prevention of the spreading of new virulent strains of C. parasitica in Europe.The expertise and technical backgrounds in the participating Azerbaijan and Italian research units are complementary, which warrants the project success. The Azerbaijan team will organized the field campaign and will provide the facilities to collect fungal isolates in the field . The Italian group has a well equipped laboratory with PCR, transmission microscope, electrophoresis and mass spectrometry facilities. Aside from achievement of the scientific objective of this project, ancillary expected benefits resulting from the cooperation will be (1) exchange of methodological experience in detecting fungal disease (2) training of young researchers; (2) publication of joint scientific papers, acknowledging ANAS-CNR support.

Adamíková K, et al.2010.Forest Pathology 40:443-449.
Aghayeva DN, Harrington TC.2008. J.Plant Pathology 57:383-385.
Anagnostakis SL et al. 1986. Plant Disease 70:536-538.
Anagnostakis SL. 2001. Forest Ecology and Management 52:225-233.
Bissegger M et al 1997. Phytopathology 87:50-59.
Brown AV et al. Plant Pathology 56:227-241.
Heiniger U, Rigling D. 1994.Annual Rev Phytopathol 32:581-599.
Lorenz MC, Gerald RF. 2001.Nature 412:83-86.
Mayer AM. 1987.Phytochemistry. 26:11-20.
Milgroom MG, Wang k, Zhou Y, Liparis E., Kaneko S. 1996. Mycologia. 88:179-190.
Rigling D, van Alfen NK. 1991. J of Bacteriology 173:8000-8003.
Rigling D, van Alfen NK. 1993.Appl. Environ. Microbial. 59: 3634-3639.
Rigling D, Heiniger U, Hohl HR1989. Phytopathology 79:219-223.
Robin C, Anziani C, Cortesi P. 2000. Phytopathology. 90:730-737
Santini A,Ghelardini L, De Pace C, et al 2013.New Phytologist 197:238-25

Research goals

The main objective of this project is to assess the presence and the spatial distribution of fungal disease
in Azerbaijan chesnuts with particular focus on C. parasitica causing chestnut blight.

The specific objectives include :
1) to characterize fungal disease of Castanea sativa;
2) to assess the diversity of the Cryphonectria parasitica population in Azerbaijan;
3) to identify a phenotypic trait associated with hypovirus infection;
4) to test isolates for the presence of the hypovirus by using dsRNA extraction and PCR based methods;
5) to characterize the putative enzyme associated to the fungal virulence and pathogenesis;
6) to characterize the putative enzyme associated to plant response to fungal attack.

Last update: 27/11/2021