Department of Forest Genetics
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New study identifies the Norway spruce defence mechanism against a rust fungus that threatens the Alps

An FWF (Austrian Science Fund)-research project co-lead by Dr. Carlos Trujillo-Moya (Austrian Federal Research Centre for Forests) and Dr. Andrea Ganthaler (University of Innsbruck) deciphers the reaction of Norway spruce (Picea abies) to infestation by the needle bladder rust fungus (Chrysomyxa rhododendri), which represents a serious threat to high-altitude forests in the Alps. The study shows that spruce trees defend themselves with a so-called "hypersensitive" reaction, in which the fungus is isolated in the infested leaves to prevent its spread. The findings promote the establishment of replanting programs that contribute to the preservation of healthy and stable high-Alpine forests.

Infection in spring

Infection with the rust fungus causes the leaves of Norwegian spruce to turn yellow in summer and fall off, which leads to a marked decline in tree growth and, in the worst case, even to death. The infection occurs in spring, when fungal spores are newly released from the pathogens’ second host, the rhododendron (Rhododendron ferrugineum or R. hirsutum), and are dispersed by the wind to the new sprouting spruce shoots.

Clones of resistant spruce

This phenomenon affects the ecological, economic and social services of forests at higher altitudes in the Alps. Dr Trujillo-Moya's research is aimed at halting this disease, which affects thousands of hectares of forest every year, causing economic damage and posing a risk to the high mountain ecosystem. “The continuous and periodic monitoring of several spruce trees exposed to this pathogen in the mountains of the Austrian Tyrol has enabled us to select trees that show enhanced resistance, to produce clones and to study in detail the gene expression and the production of chemical repellents by affected plants," Trujillo-Moya comments.

Defence through controlled cell death

The results published in the internationally renowned scientific journal BMC Genomics show that spruce defends itself by a so-called "hypersensitive" reaction. This is a very efficient defence mechanism, widespread in the plant kingdom and extensively studied for crops by which plants, as sessile organisms that live permanently anchored in the same place, prevent the spread of the disease. This defence response consists in the rapid death of cells in the local region surrounding an infection that prevents the fungus from spreading to other parts of the tree. The process includes the production of a complex composition of proteins and chemical compounds that help to isolate the fungus and prevent its growth. For spruce trees, this reaction was shown to occur two to three weeks after infection and to persist for at least one month. In this period, the tree produces a specific "ammunition" for defence. Dr. Trujillo-Moya said: "The study highlights the importance of the production of taxifolin with proven antifungal activity and of the endochitinase defense protein which is responsible for the destruction of chitinin the fungal cell wall, for this pathosystem. The result of the study represents a major advance for the selection of rust-resistant trees. Now that we know which genes and metabolic processes are activated during the spruce tree's defence process, we can select those trees that show the most effective hypersensitive defence reaction," emphasizes the forestry scientist. This finding may enable efficient and cost-effective selection of resistant clones and to establish forestation programs with these specimens, which will contribute to the preservation of the important high mountain forests of the Alps.  


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For further informations, hires- pictures and interviews: 

carlos.trujillo-moya@bfw.gv.at

Mobile:+34-600 473 671


Literature

Trujillo-Moya, C., Ganthaler, A., Stöggl, W. et al. RNA-Seq and secondary metabolite analyses reveal a putative defence-transcriptome in Norway spruce (Picea abies) against needle bladder rust (Chrysomyxa rhododendri) infection. BMC Genomics 21, 336 (2020).

https://doi.org/10.1186/s12864-020-6587-z


Links

https://pf.fwf.ac.at/en/research-in-practice/project-finder/40028

https://bfw.ac.at/rz/bfwcms.web?dok=2296

https://www.uibk.ac.at/botany/units_research_groups/ecophysiology.html.en






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Carlos Trujillo-Moya

Infected Spruces


Infected Spruce in Detail


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