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Plants can benefit from its interaction with microorganisms to make essential elements available for its growth and development, especially if this element is not available or exactly if it is not available in its assimilable form by the plant.

A simple and very well known and studied example is that of the symbiotic interaction between legumes and Rhizobia. Nitrogen is a very important element for plants, it is highly available in the atmosphere but in a form that cannot be assimilated by legumes, bacteria of the Rhizobium genus can convert it, during a symbiotic interaction, into an assimilable form for these legumes

Dr Sofiane Benyamina thank you for your contribution to the discussion

Plant deleterious rhizobacteria (PDRB) are root-associated bacteria that have a negative impact on plant growth and development. They can cause a variety of plant diseases, including wilting, root rot, and leaf blight. PDRB can also produce toxins that interfere with plant nutrient uptake and water transport.

Symbiotic associations are mutually beneficial relationships between two or more organisms. In the context of plant-microbe symbioses, the plant provides the microbe with a carbon source (food) in exchange for a variety of benefits, including:

• Nutrient acquisition: Many plant-associated microbes can help plants to acquire essential nutrients, such as nitrogen, phosphorus, and potassium. For example, nitrogen-fixing bacteria can convert atmospheric nitrogen into a form that plants can use.
• Disease protection: Some plant-associated microbes can help to protect plants from diseases caused by other microbes, fungi, or viruses. For example, one type of bacteria produces compounds that are toxic to fungal pathogens.
• Growth promotion: Some plant-associated microbes can promote plant growth by producing hormones or other signaling molecules. For example, one type of bacteria produces a hormone that stimulates root growth.

How plants benefit from having microorganisms symbiotic association:

• Increased nutrient availability: Microbes can help plants to acquire essential nutrients from the soil and air. This can lead to increased plant growth and yield.
• Improved resistance to pests and diseases: Microbes can help plants to defend themselves against pests and diseases. This can reduce crop losses and improve the quality of agricultural products.
• Enhanced tolerance to abiotic stresses: Microbes can help plants to tolerate abiotic stresses, such as drought, salinity, and heavy metal toxicity. This can improve crop productivity in marginal environments.

Examples of beneficial plant-microbe symbiotic associations:

• Legumes and nitrogen-fixing bacteria: Nitrogen-fixing bacteria live in the root nodules of legumes and convert atmospheric nitrogen into a form that plants can use. This symbiotic association allows legumes to grow in soils with low nitrogen levels.
• Grasses and mycorrhizal fungi: Mycorrhizal fungi form symbiotic associations with the roots of many plants, including grasses. Mycorrhizal fungi help plants to absorb water and nutrients from the soil. This symbiotic association is essential for the growth and survival of many plants.
• Rhizosphere bacteria: Rhizosphere bacteria are found in the soil surrounding plant roots. Many rhizosphere bacteria produce compounds that promote plant growth and protect plants from disease.

Plant deleterious rhizobacteria can disrupt these beneficial plant-microbe symbiotic associations. For example, some PDRB can produce toxins that kill nitrogen-fixing bacteria. Other PDRB can compete with mycorrhizal fungi for nutrients.

Scientists are working to develop ways to control PDRB and promote beneficial plant-microbe symbiotic associations. This research could help to improve crop productivity and reduce the need for pesticides and fertilizers.

Dr Murtadha Shukur thank you for your contribution to the discussion

Deleterious rhizobacteria (DRB) are predominantly saprophytic bacteria that aggressively colonize plant seeds, roots and rhizospheres and readily metabolize organic substances released by plant tissues. Rhizobia, the famous mutualistic symbiotic bacteria, could establish symbiotic associations with leguminous crop plants, fixing atmospheric nitrogen for the plant in specific root structures known as nodules. Rhizobacteria, through nitrogen fixation, are able to convert gaseous nitrogen (N2) to ammonia (NH3) making it an available nutrient to the host plant which can support and enhance plant growth. The host plant provides the bacteria with amino acids so they do not need to assimilate ammonia. Mycorrhizal fungi allow plants to draw more nutrients and water from the soil. They also increase plant tolerance to different environmental stresses. Mycorrhizal plants are more resistant to disease and drought. In such associations, the fungal symbiont absorbs phosphorus from the soil and sends it to the plant. Plants with these associations show other benefits as well such as tolerance to drought and salinity, resistance to root-borne pathogens and overall increase in plant growth and development. Mycorrhizal fungi, which form a mutualistic association with many plant roots, are particularly sensitive to the effects of acid rain. These fungi facilitate the absorption of water and nutrients by the plants; in turn, the plants provide sugars and amino acids without which the fungi could not survive. The relationship between plants and fungi is symbiotic because the plant obtains phosphate and other minerals through the fungus, while the fungus obtains sugars from the plant root. Mycorrhizal fungi allow plants to draw more nutrients and water from the soil. They also increase plant tolerance to different environmental stresses. Moreover, these fungi play a major role in soil aggregation process and stimulate microbial activity.