Insight into Recent Progress and Perspectives in Improvement of Antioxidant Machinery upon PGPR Augmentation in Plants under Drought Stress: A Review

Abstract

Agriculture has a lot of responsibility as the rise in the world’s population demands more food requirements. However, more than one type of biotic and abiotic stress continually impacts agricultural productivity. Drought stress is a major abiotic stress that significantly affects agricultural productivity every year as the plants undergo several morphological, biochemical, and physiological modifications, such as repressed root and shoot growth, reduced photosynthesis and transpiration rate, excessive production of reactive oxygen species (ROS), osmotic adjustments, and modified leaf senescence regulating and stress signaling pathways. Such modifications may permanently damage the plants; therefore, mitigation strategies must be developed. The use of drought resistant crop cultivars is more expensive and labor-intensive with few advantages. However, exploiting plant growth promoting rhizobacteria (PGPR) is a proven alternative with numerous direct and indirect advantages. The PGPR confers induced systemic tolerance (IST) mechanisms in plants in response to drought stress via multiple mechanisms, including the alteration of root architecture, maintenance of high relative water content, improvement of photosynthesis rate, production of phytohormones, exopolysaccharides, ACC deaminase, carotenoids and volatiles, induction of antioxidant defense system, and alteration in stress-responsive gene expression. The commercial application of PGPR as bioinoculants or biostimulants will remain contingent on more robust strain selection and performance under unfavorable environmental conditions. This review highlights the possible mechanisms of PGPR by activating the plant adaptive defense systems for enhancing drought tolerance and improving overall growth and yield.

Melatonin administration decrypts the inferential determinants of idiosyncratic foliar nastic movements

“…Stomata also inhibit the invasion of disease-causing microbes into leaves, limiting their spread. Drought causes the synthesis and/or mobilisation of the phytohormone abscisic acid (ABA), which is wellknown for its capacity to induce stomatal closure (Gowtham et al 2022;Mukherjee et al 2022). Aside from ABA, plant hormones (auxins, methyl jasmonate, ethylene, brassinosteroids, and cytokinins), plant defensins (salicylic acid and chitosan), and polyamines accumulate during drought and impact stomatal activity (Khare et al 2020).…”

Exploring the Plant Growth-Promotion of Four Streptomyces Strains from Rhizosphere Soil to Enhance Cucumber Growth and Yield

“…has been reported as the best phosphate solubilizers [ 86 ] by Sadeghi et al [ 87 ]; Jog et al [ 88 ]; and Sreevidya et al [ 89 ]. Plant growth-promoting bacteria help phosphorus solubilize, improve nutrient availability, control phytopathogens, produce phytohormones, biosynthesize metal chelators, and alleviate abiotic stress in plants [ 16 , 90 , 91 , 92 , 93 , 94 ]. These properties are considered an important practice for sustainable agriculture and good alternative practices to reduce environmental hazards with chemical fertilizers and pesticides.…”

Piper caninum extract and Brevibacillus agri mixture suppresses rice leaf spot pathogen; Nigrospora oryzae and improves the production of red rice (Oryza sativa L)

“…P. caninum also contains phytochemical substances such as Benzene, xylene, Tetradecane, dodecanoic acid, heptadecane, hexadecenoic acid, octadecamethyl cyclononasiloxa ne, Phthaic acid, and 8.11, 14-dococatrinic acid serves as fungicidal and bactericidal [33,34]. Essential oil from stems [Major compound: safrole (25.5%)] and leafs [Major compound: safrole (17.1%)] have antimicrobial and antioxidant activities (Salleh et al, 2015;Najafi et al, 2021;Gowtham et al, 2022). Plant extracts offer antifungal benefits (Arora et al, 2022) as they activate typical defense-related responses such as the production of H 2 O 2 , the up-regulation of genes encoding pathogenesis-related proteins, stilbene synthase, and the accumulation of resveratrol or its derivative piceid.…”