Vesicular arbuscular mycorrhiza (VAM) is a type of endomycorrhiza, a symbiotic relationship between fungi and the roots of vascular plants. VAM fungi penetrate the cortical cells of the roots, forming arbuscules, specialized structures for nutrient exchange. This mutualistic symbiosis provides benefits to both partners: the fungi help plants capture nutrients from the soil, while the plants provide the fungi with carbohydrates for energy.
Key Facts
- Definition: Vesicular arbuscular mycorrhiza (VAM) is a type of endomycorrhiza, where the symbiont fungus penetrates the cortical cells of the roots of a vascular plant, forming arbuscules.
- Occurrence: VAM fungi are known to occur globally in a broad range of dissimilar environments, from arctic to tropic regions, and occupy a wide range of ecological niches.
- Symbiotic Relationship: VAM fungi form a mutualistic relationship with plants, providing benefits to both partners. The fungi help plants capture nutrients such as phosphorus, sulfur, nitrogen, and micronutrients from the soil.
- Ecological Importance: The development of the vesicular arbuscular mycorrhizal symbiosis played a crucial role in the initial colonization of land by plants and in the evolution of vascular plants.
- Plant Associations: VAM fungi form associations with the roots of most terrestrial plants, including many agricultural crops. They are found in 80% of vascular plant families in existence today.
Global Occurrence and Ecological Importance
VAM fungi are found globally in diverse environments, from arctic to tropic regions, and occupy a wide range of ecological niches. They play a crucial role in nutrient cycling and ecosystem functioning. VAM fungi enhance the ability of plants to absorb water and nutrients from the soil, particularly phosphorus, sulfur, nitrogen, and micronutrients. In return, the fungi receive carbohydrates from the plants, which they use for energy and growth.
Evolutionary Significance
The development of the VAM symbiosis is considered a key event in the evolution of terrestrial plants. It facilitated the initial colonization of land by plants and contributed to the evolution of vascular plants. VAM fungi provided early plants with access to essential nutrients in nutrient-poor soils, allowing them to thrive in diverse environments.
Plant Associations and Agricultural Importance
VAM fungi form associations with the roots of most terrestrial plants, including many agricultural crops. Approximately 80% of vascular plant families in existence today have VAM associations. These fungi play a significant role in agricultural productivity by enhancing nutrient uptake and improving plant growth and stress tolerance.
Conclusion
VAM is a widespread and ecologically important symbiosis between fungi and plants. VAM fungi provide plants with essential nutrients, while plants provide the fungi with carbohydrates. This mutualistic relationship has played a crucial role in the evolution of terrestrial plants and continues to contribute to the success of many plant species in diverse ecosystems.
References
- Smith, S.E., Read D.J. (2008). Mycorrhizal symbiosis. New York: Academic Press.
- van der Heijden, M.G.A., Martin, F.M., Selosse, M.A., Sanders, I.R. (2015). Mycorrhizal ecology and evolution: the past, the present, and the future. New Phytologist. 205: 1406-1423.
- INVAM: The International Collection of (Vesicular) Arbuscular Mycorrhizal Fungi. University of Kansas. [Online] Available at: https://invam.ku.edu/ [Accessed 2023].
FAQs
What is vesicular arbuscular mycorrhiza (VAM)?
Vesicular arbuscular mycorrhiza (VAM) is a type of endomycorrhiza, a mutualistic symbiosis between fungi and the roots of vascular plants. VAM fungi penetrate the cortical cells of the roots, forming arbuscules, specialized structures for nutrient exchange.
Where are VAM fungi found?
VAM fungi are found globally in diverse environments, from arctic to tropic regions, and occupy a wide range of ecological niches. They are particularly common in nutrient-poor soils.
What are the benefits of VAM to plants?
VAM fungi provide plants with essential nutrients, particularly phosphorus, sulfur, nitrogen, and micronutrients. They also help plants absorb water more efficiently and improve their tolerance to drought, salinity, and heavy metals.
What are the benefits of VAM to fungi?
VAM fungi receive carbohydrates from the plants, which they use for energy and growth. This mutualistic relationship allows both partners to thrive in nutrient-poor environments.
How do VAM fungi form associations with plants?
VAM fungi form associations with plants through a process called mycorrhizal colonization. Fungal spores germinate in the soil and hyphae grow towards plant roots. The hyphae penetrate the root cortex and form arbuscules, specialized structures for nutrient exchange.
What is the ecological importance of VAM?
VAM fungi play a crucial role in nutrient cycling and ecosystem functioning. They help plants absorb nutrients from the soil, which can then be released back into the environment through decomposition. VAM fungi also improve soil structure and stability.
Are VAM fungi found in agricultural systems?
Yes, VAM fungi are found in agricultural systems and can benefit crop plants. They help crops absorb nutrients more efficiently, which can lead to increased yields and reduced fertilizer requirements. VAM fungi can also improve crop tolerance to drought, salinity, and pests.
How can I promote VAM colonization in my plants?
There are several ways to promote VAM colonization in plants. These include:
- Using mycorrhizal inoculum when planting
- Reducing the use of chemical fertilizers and pesticides
- Maintaining soil moisture levels
- Avoiding soil compaction
- Using organic matter to improve soil health