Definition structure and functions of VAM in plant roots
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.
(Image will be uploaded soon)
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 VAM Vesicular Arbuscular Mycorrhiza in Plants
1. What is VAM in biology?
VAM stands for Vesicular Arbuscular Mycorrhiza, a type of symbiotic association between certain fungi and plant roots. It is now more commonly called Arbuscular Mycorrhiza (AM).
- It involves fungi from the phylum Glomeromycota.
- The fungus penetrates the root cortex of plants.
- Both the plant and fungus benefit from this mutual relationship.
2. What is the function of VAM in plants?
The main function of VAM is to enhance nutrient and water absorption in plants.
- Increases uptake of phosphorus (P), zinc, and other minerals.
- Improves water absorption during drought conditions.
- Enhances plant growth and yield.
- Provides resistance against certain soil pathogens.
3. How does VAM infection occur in plant roots?
VAM infection occurs when fungal spores germinate in the soil and penetrate the root cortex of a host plant.
- Fungal spores germinate near plant roots.
- Hyphae attach to the root surface.
- The fungus penetrates the epidermis and cortex.
- Special structures called arbuscules and vesicles are formed inside root cells.
4. What are arbuscules and vesicles in VAM?
Arbuscules and vesicles are specialized fungal structures formed inside plant roots during VAM association.
- Arbuscules: Branched structures that facilitate nutrient exchange between fungus and plant.
- Vesicles: Spherical storage structures that store lipids and nutrients.
5. What is the difference between VAM and ectomycorrhiza?
The key difference is that VAM penetrates root cortical cells, while ectomycorrhiza does not enter the cells.
- VAM forms arbuscules and vesicles inside root cells.
- Ectomycorrhiza forms a fungal sheath (mantle) around roots.
- VAM is common in herbaceous plants and crops.
- Ectomycorrhiza is common in forest trees like pine and oak.
6. Why is VAM important in agriculture?
VAM is important in agriculture because it improves crop productivity and reduces fertilizer dependence.
- Enhances phosphorus uptake from soil.
- Reduces need for chemical fertilizers.
- Improves soil structure and fertility.
- Increases plant tolerance to drought and disease.
7. Can you give examples of plants that form VAM?
Most terrestrial plants form VAM associations with fungi.
- Crop plants like wheat, maize, rice, and soybean.
- Vegetables such as tomato and onion.
- Fruit plants like citrus and mango.
8. What type of symbiotic relationship is VAM?
VAM is a mutualistic symbiosis where both the plant and fungus benefit.
- The plant provides carbohydrates produced by photosynthesis.
- The fungus supplies minerals and water from the soil.
9. How does VAM help in phosphorus absorption?
VAM helps in phosphorus absorption by extending fungal hyphae deep into the soil beyond the root zone.
- Hyphae increase the surface area for absorption.
- They access immobile phosphate ions in soil.
- Phosphorus is transferred to the plant through arbuscules.
10. Is VAM considered a biofertilizer?
Yes, VAM is considered a biofertilizer because it naturally enhances plant nutrient uptake and soil fertility.
- Reduces chemical fertilizer requirements.
- Promotes sustainable agriculture.
- Improves plant growth and yield.
