How VAM Enhances Nutrient Uptake and Plant Health
Symbiotic fungi are quite helpful for the plants to fixate on certain nutrients from the surrounding. One such strain is Vesicular Arbuscular Mycorrhiza. It is commonly recognized as VAM. This type of fungus forms a mutually beneficial relationship with bigger plants that can perform photosynthesis. The fungus offers something that this plant cannot acquire whereas the plant gives it nutrition. In this article, we will find out the special features of this fungus and its utilization in agriculture.
What is VAM?
VAM fungi are mycorrhizal species of fungus that live in the roots of different higher-order plants. They develop a symbiotic relationship with the plants in the roots of these plants. This type of fungus can penetrate and enter the cortical cells of vascular tissues of plants and form an arbuscule. They are different from the ericoid mycorrhiza in this aspect.
The prime features that help to determine this fungus are its vesicular or arbuscule formation. The unique structural features of this fungus add it to the Phylum Glomeromycota. The prime function of this fungus is to capture important nutrients from the soil such as sulfur, nitrogen, phosphorus, and other micronutrients for the host plants. The host plants, on the other hand, provide nutrition by performing photosynthesis.
As per the paleobotanists, the evolution of vascular plants and colonization of land plants in the prehistoric era is directly linked to the development of this symbiotic phenomenon of VAM. The higher-order plants started to develop vascular tissues that can absorb and carry water from the soil. The symbiotic relationship resulted in the propagation of the plants in the land from the water sources as they got the special nutrients fixated by these fungi.
Hence, the symbiosis process performed by this fungus is highly evolved and mutual. In fact, more than 80% of the symbiotic relationships between vascular plants and fungus can be noticed in this species.
Over the years, advanced research has been conducted on the ecological effects of mycorrhizal symbiosis that led to the foundation of various benefits. This symbiotic relationship plays multiple roles for the ecosystem. For instance, VAM produces a glue-like protein named Glomalin that helps in maintaining the soil structure. The common mycorrhizal fungi examples that perform symbiosis are larch trees, conifers, oak, beech, etc.
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Uses of Arbuscular Mycorrhiza
As mentioned earlier, this fungus has excellent symbiotic features that can be used in the restoration of deserted lands. Let us take a quick look at these excellent uses of this fungus in the agricultural field.
Phytoremediation
The prime benefit of the symbiotic process of this fungus and the phenomenon of fixating essential elements to the land can be depicted as VAM biofertilizer. This biofertilizer can be used for enhancing the fertility of the abandoned lands and can make them cultivable again.
The soil structure and nutrition availability drastically improve when this fungus is used as a new approach. The process involves the inoculation of this fungus in the soil while reintroducing vegetation. This is called an ecological restoration project. This process increases soil quality and improves the health of the plants.
By adding this fungus, the nitrogen content and organic matter percentage in the soil increases. In fact, it also results in soil aggregation and preservation of the available nutrients for plant growth.
Tillage
Another good use of vesicular fungus is to reduce the requirement of tilling the lands. Due to excess tillage, the macromolecular structure of the soil is disrupted resulting in loss of phosphorus level to a considerable extent. Hence, adding this fungus for phytoremediation, the tillage requirements reduce and the integrity of the soil is retained for a longer period.
Phosphorus Fertilizer
As mentioned earlier, this type of symbiotic alliance can be found in more than 80% of the plants involved in such natural relationships. The ability to dissolve the phosphates available in the soil and fixate them to provide them to the plants makes this fungus a natural phosphorus fertilizer. This ability enhances the harvest in all possible ways. It also enhances the percentage of other trace elements necessary for the growth of host plants.
It is obvious that a higher-order plant’s biological process and lifecycle depends on this element. Hence, the easy availability of phosphorus will result in proper growth and accomplishment of all the biological functions of a plant. The plant, on the other hand, can share the produce of carbohydrates with the fungi present in the roots. This is a prominent use of the mycorrhizal biofertilizer in several agricultural processes.
Warding off Root Diseases
As this fungus colonizes in the roots of the plants, it also forms a shield against various other infectious diseases affecting the plant’s growth.
This is a small summary of this fungus and its exceptional use in the agricultural field. In terms of biological characteristics, it is different from the other mycorrhizal fungi species. Find out the uses of the natural VAM fertilizer and learn how it enhances the features of cultivable soil. Learn how this fungus has contributed to the agricultural field.
FAQs on Vesicular Arbuscular Mycorrhiza (VAM): Key Concepts & Uses
1. What is Vesicular Arbuscular Mycorrhiza (VAM)?
Vesicular Arbuscular Mycorrhiza (VAM) is a type of endotrophic mycorrhiza, which is a symbiotic association between certain fungi, primarily from the Phylum Glomeromycota, and the roots of over 80% of terrestrial plants. The fungus penetrates the cortical cells of the plant's roots to form two key structures: arbuscules (tree-like structures for nutrient exchange) and vesicles (oval structures for nutrient storage).
2. What is the primary role of VAM in a plant's ecosystem?
The primary role of VAM is to significantly enhance the plant's ability to absorb nutrients and water from the soil. The fungal hyphae extend far beyond the plant's root system, acting as an extension to explore a larger soil volume. They are particularly crucial for the uptake of immobile nutrients like phosphorus, but also improve the absorption of nitrogen, zinc, sulfur, and other essential micronutrients.
3. How do the 'arbuscules' and 'vesicles' in VAM specifically help the host plant?
The arbuscules and vesicles perform distinct but complementary functions for the host plant.
- Arbuscules are highly branched, tree-like structures that form inside the root cells. They are the primary site of nutrient transfer, where the fungus delivers minerals like phosphorus to the plant in exchange for carbohydrates (sugars) produced by the plant through photosynthesis.
- Vesicles are balloon-like storage organs. They store lipids and other nutrients, acting as a reserve for the fungus and ensuring the long-term survival of the symbiotic relationship.
4. Why is VAM widely used as a biofertilizer in agriculture?
VAM is considered an excellent biofertilizer because it naturally improves soil fertility and plant growth, reducing the need for chemical fertilizers. Its key benefits include:
- Phosphorus Mobilisation: It unlocks and makes soil phosphorus available to plants.
- Improved Soil Structure: VAM fungi produce a protein called Glomalin, which acts as a glue to bind soil particles, improving soil aggregation, water retention, and aeration.
- Enhanced Nutrient Uptake: It increases the uptake of various other essential nutrients, leading to healthier and more robust plants.
- Drought Resistance: The extensive fungal network helps plants access water from deeper soil layers.
5. How does VAM contribute to the ecological restoration of barren lands?
VAM plays a crucial role in phytoremediation and the restoration of degraded or barren lands. When inoculated into poor-quality soil, VAM fungi help establish new vegetation by providing a vital nutrient supply, especially phosphorus, which is often limited. This improves plant survival and growth, increases the soil's organic matter over time, and helps in soil aggregation, preventing erosion and kickstarting the recovery of the ecosystem.
6. What are some common examples of plants that form a relationship with VAM fungi?
The VAM association is extremely common across the plant kingdom. The vast majority of agricultural and horticultural crops form this symbiotic relationship. Common examples include:
- Cereals: Maize, wheat, rice, and barley.
- Legumes: Peas, beans, and lentils.
- Horticultural Crops: Tomatoes, potatoes, onions, and most fruit trees like citrus and apple.
7. How does VAM help protect plants from root diseases?
VAM provides protection against root pathogens through several mechanisms. Firstly, the dense network of fungal hyphae colonising the root system creates a physical barrier that makes it difficult for pathogens to reach and infect the root. Secondly, VAM fungi compete with pathogens for resources like sugars exuded by the root. Finally, the association can trigger the plant's own defence mechanisms, leading to an enhanced state of resistance against future infections.
8. If VAM is so beneficial, why don't all plants have this symbiotic relationship?
While incredibly widespread, the VAM symbiosis is not universal due to evolutionary differences. Some plant families, like the Brassicaceae (cabbage family), have evolved alternative strategies for nutrient acquisition, such as highly efficient root hairs, and possess chemical compounds that can be inhibitory to mycorrhizal fungi. Similarly, many aquatic plants do not form these associations as nutrients are more readily available in their dissolved environment, making the symbiosis less advantageous.
