麻豆淫院

University of Alberta research is showing how trees and fungi team up to survive and stay healthy against insect attacks鈥攁n alliance that could lead to more resilient forests.

Endophytes鈥攖iny micro-organisms made up of bacteria and fungi living harmlessly in the tissues of white spruce鈥攈elp the tree defend itself by producing toxic compounds that repel or kill eastern spruce budworm, the new study showed.

The discovery provides a "clear, detailed explanation" of how the fungi help protect the tree against the defoliating insect, says forest entomologist Nadir Erbilgin, a professor in the Faculty of Agricultural, Life & Environmental Sciences who supervised the study.

"The work represents a big step forward in understanding natural pest resistance in white spruce and potentially for all conifer tree species," he adds.

"It's like discovering that trees have secret allies working behind the scenes to protect them."

To learn more about how endophytes help protect trees, the researchers collected needles from mature white spruce and identified resident fungi through DNA sequencing, then further grew some of the fungi in a lab. They also inoculated white spruce seedlings with a blend of fungal endophytes to determine whether changes in those fungal communities altered tree defense chemistry.

The results showed that the fungal endophytes help the trees defend against the pest in two ways, "by both strengthening the tree's natural defenses and fighting off the insect directly," says Aziz Ullah, who led the study to earn a Ph.D. in forest biology and management.

First, the endophytes boost the tree's own chemical defenses by increasing the production of terpenes, metabolites in the tree that help launch a chemical defense against infestation, along with other natural compounds that help deter insects.

As well, the fungi themselves produce toxic substances, either through their tissue or by releasing volatile organic compounds, that can directly harm or kill budworm larvae.

The findings confirm the "Plant Partnership Hypothesis," which was developed and tested by the researchers involved in the study. The supposition was that the fungi help produce chemicals that make the plant more resistant to pests. In exchange, the fungi benefit from living inside the plant and drawing nutrients from it.

"By proving the hypothesis, we've shown that fungal endophytes are not just passive passengers; they've evolved together with the plant over time to support each other in ways that improve the tree's survival, especially in deterring insect attacks," Ullah notes.

The study opens up new research avenues and industry potential for how that alliance could be used to help protect forests and control insect pests, Erbilgin says.

"Agricultural and forestry researchers and companies could benefit by developing more natural, sustainable strategies to protect forests from budworm outbreaks, potentially reducing tree mortality without relying heavily on chemical pesticides."

Knowing specific endophytes can boost tree defenses or repel budworms also offers possibilities for selecting, breeding or inoculating trees with beneficial fungal partners, he notes.

"This could lead to healthier forests that are more resilient to pest pressures."

The findings could also help control other insect pest populations in other economically and ecologically important conifer species, he adds, noting that his lab is now conducting similar experiments on lodgepole pine, against the mountain pine beetle.

The findings are in the journal Plant, Cell & Environment.