Forest Tree Virome as a Source of Tree Diseases and Biological Control

Academic Background

The health of forest ecosystems is crucial for global ecological balance and economic development. However, the health of forest trees is threatened by various pathogens, including fungi, oomycetes, bacteria, viruses, as well as insect and nematode pests. Although fungi and insects are considered the primary factors causing economic losses in forests, the widespread presence of plant viruses in forest and urban trees and their negative impact on tree health have gradually been recognized in recent years. Viruses can not only directly cause tree diseases but also affect tree metabolism and immune systems, making them more susceptible to other biotic and abiotic stresses.

Furthermore, fungal viruses (mycoviruses) as potential biological control tools have also garnered significant attention in recent years. By studying mycoviruses, scientists hope to utilize these viruses to control the growth and spread of forest pathogenic fungi, thereby reducing their damage to forest ecosystems.

Source of the Paper

This review paper was co-authored by Eeva J. Vainio (Natural Resources Institute Finland), Artemis Rumbou (Humboldt University of Berlin), Julio J. Diez (University of Valladolid), and Carmen Büttner (Humboldt University of Berlin), and published in the February 2024 issue of Current Forestry Reports. The paper, titled Forest Tree Virome as a Source of Tree Diseases and Biological Control Agents, aims to summarize the latest advancements in the field of forest tree virology over the past five years, particularly focusing on research findings related to plant viruses and mycoviruses.

Main Content of the Paper

1. Advances in Forest Tree Virome Research

The paper first reviews the progress in forest tree virome research. The virome not only includes plant viruses but also encompasses virus communities carried by all tree-associated organisms (such as fungi, insects, etc.). In recent years, the application of High-Throughput Sequencing (HTS) technology has significantly advanced research on virus diversity and transmission pathways. Through HTS, scientists have discovered many new virus species and revealed cross-species transmission phenomena among fungi, oomycetes, plants, and arthropods.

1.1 Impact of Plant Viruses on Forest Trees

Plant viruses can cause various tree diseases, affecting tree growth and health. The paper lists several common forest tree virus diseases, such as Birch Leafroll Disease (BLRD), Chestnut Mosaic Disease (CHMD), and Ash Shoestring Disease. These diseases often manifest as leaf discoloration, curling, necrosis, and in severe cases, can lead to tree decline or even death.

1.2 Potential of Mycoviruses as Biological Control Tools

Mycoviruses can weaken the pathogenicity of their host fungi, offering new avenues for biological control. The paper discusses in detail the potential applications of mycoviruses in controlling forest pathogenic fungi, particularly those that induce “hypovirulence” in fungi. For example, Cryphonectria hypovirus 1 (CHV-1) is a widely studied mycovirus that significantly reduces the pathogenicity of its host fungus Cryphonectria parasitica, effectively controlling chestnut blight.

2. Virus Transmission Pathways and Ecological Impact

The paper also explores the transmission pathways of viruses in forest ecosystems. Viruses can be transmitted through vectors such as insects, nematodes, and fungi, as well as through grafting, mechanical transmission, and seed dispersal. Additionally, viruses can spread over long distances via water and soil. The paper highlights that the diversity of virus transmission pathways makes the spread and diffusion of viruses in forest ecosystems complex and uncertain.

2.1 Cross-Species Virus Transmission

In recent years, cross-species virus transmission has attracted significant attention. The paper mentions that viruses can not only transmit between plants and fungi but also between fungi and insects. This cross-species transmission phenomenon provides new pathways for virus diffusion in ecosystems while also increasing the potential threat of viruses to forest health.

3. Future Research Directions and Recommendations

The paper concludes by proposing future research directions and recommendations. The authors suggest that future research should focus on the following areas: 1. Virus Diversity and Functional Studies: Continue exploring the diversity of forest tree viromes and conduct in-depth research on virus functions and their impact on tree health. 2. Virus Transmission Mechanisms: Further investigate virus transmission pathways, particularly the role of insects and fungi as virus vectors. 3. Biological Control Applications: Evaluate the potential of mycoviruses as biological control tools, especially their effectiveness in field conditions. 4. Impact of Climate Change: Study the effects of climate change on virus transmission and tree diseases, predicting potential future virus outbreak risks.

Significance and Value of the Paper

This review paper systematically summarizes the latest research advancements in the field of forest tree virology, particularly focusing on plant viruses and mycoviruses. The paper not only provides scientists with new insights into virus diversity and transmission pathways but also offers new ideas for the biological control of forest diseases. By delving deeper into the role of viruses in forest ecosystems, scientists can better understand the impact of viruses on tree health and develop more effective control strategies.

Additionally, the paper emphasizes the potential risks of cross-species virus transmission, reminding scientists to pay closer attention to virus diffusion pathways in ecosystems and their long-term impact on forest health in future research.

Highlights

1. New Discoveries in Virus Diversity: Through high-throughput sequencing technology, scientists have discovered many new virus species, revealing the complexity and diversity of viruses in forest ecosystems.
2. Biological Control Potential of Mycoviruses: The paper discusses in detail the potential applications of mycoviruses in controlling forest pathogenic fungi, particularly those that induce hypovirulence in fungi.
3. Research on Cross-Species Virus Transmission: The paper highlights the importance of cross-species virus transmission, providing new directions for future virus research.

This paper not only serves as an important reference for research in the field of forest virology but also offers new ideas and methods for the control of forest diseases.