Plant growth-promoting activity of rhizosphere

The rhizosphere is the region of soil surrounding plant roots that is influenced by root exudates. It is a highly dynamic and complex environment that is home to a diverse community of microorganisms, including bacteria, fungi, and protozoa. Some of these microorganisms are beneficial to plants and can promote their growth and development. These beneficial microorganisms are collectively known as plant growth-promoting rhizobacteria (PGPR).

PGPR can promote plant growth in a variety of ways, including:

• Nitrogen fixation: Some PGPR can fix atmospheric nitrogen and make it available to plants.
• Nutrient solubilization: PGPR can solubilize nutrients such as phosphorus and potassium, making them more available to plants.
• Phytohormone production: PGPR can produce plant hormones such as auxin, cytokinin, and gibberellin, which can promote plant growth and development.
• Induced systemic resistance: PGPR can induce systemic resistance in plants, making them more resistant to pests and diseases.

Role of PGPR in mitigating plant's environmental stresses

PGPR can also play a role in mitigating plant's environmental stresses, such as salinity, drought, and heavy metal contamination. For example:

• Salinity stress: PGPR can help plants to cope with salinity stress by increasing their osmoprotectant levels, improving their water uptake, and reducing their salt uptake.
• Drought stress: PGPR can help plants to cope with drought stress by increasing their root surface area, improving their water uptake, and increasing their production of abscisic acid, a hormone that helps plants to conserve water.
• Heavy metal contamination: PGPR can help plants to cope with heavy metal contamination by chelating the metals, making them unavailable to the plant, or by increasing the plant's tolerance to the metals.

Overall, PGPR are a diverse group of beneficial bacteria that can play a significant role in promoting plant growth and development, and in mitigating plant's environmental stresses.

Here are some specific examples of how PGPR have been shown to mitigate plant's environmental stresses:

• A study published in the journal Plant and Soil found that PGPR inoculation could improve the growth and yield of maize plants grown under saline conditions.
• A study published in the journal BMC Plant Biology found that PGPR inoculation could improve the growth and drought tolerance of barley plants grown under drought conditions.
• A study published in the journal Environmental Science and Pollution Research found that PGPR inoculation could reduce the uptake of lead and cadmium by wheat plants grown in heavy metal-contaminated soil.

PGPR have the potential to be used as a sustainable and environmentally friendly way to improve crop productivity and reduce the use of chemical fertilizers and pesticides.

Dr Murthada Shukur thank you for your contribution to the discussion

Properties and Potential of Plant Growth-Promoting Rhizobacteria (PGPR) Plant growth-promoting bacteria (PGPR) are soil bacteria living in the rhizosphere which, through the secretion of various regulatory molecules, are involved in promoting plant growth and development. Plant growth promoting rhizobacteria (PGPR) is a group of bacteria that can be found in the rhizosphere. “Plant growth promoting bacteria” refers to bacteria that colonize the roots of plants (rhizosphere) that enhance plant growth. Plant growth-promoting bacteria (PGPB) are bacteria that can enhance plant growth and protect plants from disease and abiotic stresses through a wide variety of mechanisms; those that establish close associations with plants, such as the endophytes, could be more successful in plant growth promotion. The increased microbial number and activity in the rhizosphere compared to those in bulk soil are mainly due to the release of organic carbon by the plant roots. PGPR may promote plant growth by using their own metabolism, by directly affecting the plant metabolism (increasing the uptake of water and minerals), enhancing root development, increasing the enzymatic activity of the plant, by “helping” other. PGPR colonize plant roots, which leads to direct or indirect plant growth promotion, and protection from drought stress and disease. Several PGPR influence plant development through interactions with plants and their metabolic activities. Some rhizobacteria are able to produce phytohormones, including cytokinins, auxins, gibberellins, ethylene, and abscisic acid (ABA), which play a role in different growth processes in plants, including cell multiplication, which results in increased cell and root expansion. PGPR can aid growth by modifying this hormonal balance in the host-plant, which can play a role in the host-plant response to drought stress. PGPR generated CK stimulate plant cell division, cell expansion, root and shoot growth, root hair proliferation, and increase root surface area. Plant growth promoting rhizobacteria (PGPR) living on plant roots and promoting plant growth are critical to plant growth. These PGPRs exert their effects by facilitating food intake, helping to counteract pathogen attack, and regulating plant hormone levels. The major mechanisms adopted by PGPR to overcome drought stress include alteration in root morphology and production of osmolytes, antioxidants, phytohormones, extracellular polymeric substance (EPS), and volatile organic compounds (VOCs), siderophores, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase.