An Insight into the Role of Phenolics in Abiotic Stress Tolerance in Plants: Current Perspective for Sustainable Environment

Phenolic compounds (PCs) are a prominent class of secondary metabolites produced by plants and are essential for the natural role of the entire plant life cycle. PCs are formed in plants under both favorable and unfavorable conditions and have essential functions in signaling pathways, such as cell division, nutrient mineralization, hormone control, and reproduction. Under abiotic stress conditions, plants produce more polyphenols, which aid them in adapting to their environment. The phenylpropanoid biosynthetic pathway is activated under various environmental stress conditions, such as drought, heavy metal toxicity, salinity, and high/low temperatures, resulting in the deposition of compounds. These compounds can neutralize reactive oxygen species (ROS) produced in excessive amounts in crops under stressful conditions and adversely affect plants. It is imperative to investigate the functions of PCs in response to several abiotic stresses, as the phenylpropanoid pathway plays a crucial role in the metabolic pathway in crop plants, leading to the biosynthesis of a wide range of PCs. These compounds play various roles in plant growth, development, and response to environmental stress. Therefore, this review provides a comprehensive understanding of PCs and their exchanges with other cellular components, which is crucial for harnessing their potential to improve crop resilience to environmental stresses

Decrypting the multi-functional biological activators and inducers of defense responses against biotic stresses in plants

Plant diseases are still the main problem for the reduction in crop yield and a threat to global food security. Additionally, excessive usage of chemical inputs such as pesticides and fungicides to control plant diseases have created another serious problem for human and environmental health. In view of this, the application of plant growth-promoting rhizobacteria (PGPR) for controlling plant disease incidences has been identified as an eco-friendly approach for coping with the food security issue. In this review, we have identified different ways by which PGPRs are capable of reducing phytopathogenic infestations and enhancing crop yield. PGPR suppresses plant diseases, both directly and indirectly, mediated by microbial metabolites and signaling components. Microbial synthesized anti-pathogenic metabolites such as siderophores, antibiotics, lytic enzymes, hydrogen cyanide, and several others act directly on phytopathogens. The indirect mechanisms of reducing plant disease infestation are caused by the stimulation of plant immune responses known as initiation of systemic resistance (ISR) which is mediated by triggering plant immune responses elicited through pathogen-associated molecular patterns (PAMPs). The ISR triggered in the infected region of the plant leads to the development of systemic acquired resistance (SAR) throughout the plant making the plant resistant to a wide range of pathogens. A number of PGPRs including Pseudomonas and Bacillus genera have proven their ability to stimulate ISR. However, there are still some challenges in the large-scale application and acceptance of PGPR for pest and disease management. Further, we discuss the newly formulated PGPR inoculants possessing both plant growth-promoting activities and plant disease suppression ability for a holistic approach to sustaining plant health and enhancing crop productivity

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Rock Phosphate Solubilizing Potential of Soil Microorganisms: Advances in Sustainable Crop Production

Phosphorus (P) is one of the most important elements required for crop production. The ideal soil pH for its absorption by plants is about 6.5, but in alkaline and acidic soils, most of the consumed P forms an insoluble complex with calcium, iron, and aluminum elements and its availability for absorption by the plant decreases. The supply of P needed by plants is mainly achieved through chemical fertilizers; however, in addition to the high price of these fertilizers, in the long run, their destructive effects will affect the soil and the environment. The use of cheap and abundant resources such as rock phosphate (RP) can be an alternative strategy for P chemical fertilizers, but the solubilization of P of this source has been a challenge for agricultural researchers. For this, physical and chemical treatments have been used, but the solution that has recently attracted the attention of the researchers is to use the potential of rhizobacteria to solubilize RP and supply P to plants by this method. These microorganisms, via. mechanisms such as proton secretion, organic and mineral acid production, siderophore production, etc., lead to the solubilization of RP, and by releasing its P, they improve the quantitative and qualitative performance of agricultural products. In this review, addressing the potential of rhizosphere microbes (with a focus on rhizobacteria) as an eco-friendly strategy for RP solubilization, along with physical and chemical solutions, has been attempted