Scientists unlock molecular defense in alpine trees

Researchers have found a way to fight a disease that threatens thousands of hectares of alpine forests every year.

Needle bladder rust causes the needles of Norway spruce to turn yellow and drop, resulting in significant reduction in growth.

Austrian scientists have unlocked a natural defense mechanism that the species can use to fend off the potentially deadly pathogen.

The results were published in the journal BMC Genomics.

Disease is one of the main threats facing trees around the world, especially in a warming world where many organisms live in an environment in which they are under increasing stress levels.

It is widely predicted that invasive pathogens, and the insects that can spread them, are expected to thrive in a world facing climate change.

In terms of evolution, harmful pathogens have developed alongside plants’ attempts to protect themselves, creating a millennial cold war between biological realms.

This is a natural defense mechanism that a team of scientists used to create a system for protecting Norway spruce against bladder rust.

• Genetics can play a key role in saving trees

Selection of trees

“Our research aims to curb this disease by disentangling the molecular defense mechanism of Norway spruce against needle bladder rust,” said co-author Carlos Trujillo Moya, a researcher at the Austrian Research Center for forests.

Dr Trujillo Moya and his colleagues continued to monitor Norwegian spruce trees in the Austrian mountains, allowing the team to select trees that appear to be resistant to the disease.

From these trees, the team was able to generate clones, then study genes, as well as study the production of defense chemicals.

Dr Trujillo Moya told BBC News trees that showed resistance to needle bladder rust were defending themselves via a “hypersensitive response”.

“This defense mechanism consists of the production of a complex artillery of proteins and chemical compounds which isolate the fungus in the attacked leaves,” he explained.

“The infected part of the leaf dies in a controlled manner and thus prevents the fungus from spreading to the rest of the tree.

“This response occurs two to three weeks after infection and lasts for at least a month.”

The team said the results represented “huge progress” in how Norway spruce is bred for its resistance to the needle rust pathogen (Chrysomyxa rhododendron).

“Our discovery allows better identification of resistant clones and promotes the establishment of replanting programs using selected trees, based on the most effective hypersensitive defense response,” observed Dr Trujillo Moya.

He concluded by stating that this research is helping to tackle one of the main issues facing the ecological and economic sustainability of Alpine ecosystems.