14 April 2023

Research update: Fighting a threat to alder

Emma Fuller and Dheeraj Rathore report on the Irish Research Council funded ExAl project.

Common alder (Alnus glutinosa) is a native tree species with remarkable ecological importance, particularly within wetlands. Alder has the ability to promote diversity due to its soil nutrient enrichment qualities and colonisation abilities to fix nitrogen (N). Alder trees can be frequently found alongside rivers, providing stability to the banks, preventing soil erosion, as well as providing a valuable habitat and food sources to diverse wildlife.

Throughout Europe, alder has suffered from decline due to the infection of a waterborne pathogen known as Phytophthora alni. The infection typically causes root and collar rot, as well as severe dieback and/or death in some cases.

Alder dieback remains an issue within alder stands, and its continuous spread potentially threatens the species across Europe. It is likely to threaten alder within Irish landscapes in the near future.

The Exploiting Alder (ExAl) microbiome project started in September 2022 with an overall aim of investigating the microbiota of alder trees and their associated rhizosphere to identify potential bio-agents that could help improve the disease tolerance against Phytophthora alni. Research shows that the beneficial microbiota can promote plant health directly as bio-stimulants, and/or indirectly as biocontrol agents against pests and pathogens. This research project will:

1. Study the core microbial composition of alder;
2. Culture the cultivable microbes that can potentially be used as bio-agents;
3. Perform antagonistic studies of these cultivable microbes against the pathogen.

In addition, the ExAl project will investigate the microbiome of susceptible versus tolerant alder genotypes, isolate culturable microbes to test for antagonistic activity against Phytophthora alni, and exploit potential bio-agents to enhance disease tolerance in susceptible alder genotypes. This is a collaborative project with Dr. Kieran Germaine, South East Technological University (SETU) Carlow and Dr. Dheeraj Rathore, Teagasc. The research for this project is funded by the Irish Research Council’s Government of Ireland Postgraduate Scholarship Programme.

Click here for more information on the exal project