The Contribution of PGPR in Salt Stress Tolerance in Crops: Unravelling the Molecular Mechanisms of Cross-Talk between Plant and Bacteria
Gianluigi Giannelli,
Silvia Potestio,
Giovanna Visioli
Abstract:Soil salinity is a major abiotic stress in global agricultural productivity with an estimated 50% of arable land predicted to become salinized by 2050. Since most domesticated crops are glycophytes, they cannot be cultivated on salt soils. The use of beneficial microorganisms inhabiting the rhizosphere (PGPR) is a promising tool to alleviate salt stress in various crops and represents a strategy to increase agricultural productivity in salt soils. Increasing evidence underlines that PGPR affect plant physiolog… Show more
“…It has been reported that PGPBs protect plants through increasing the antioxidant ability (Ali et al, 2021 ; Giannelli et al, 2023 ; Gururani et al, 2013 ; Jaleel et al, 2007 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Singh et al, 2020 ). Plants have evolved two key defense mechanisms against the accumulation of excessive ROS: enzymatic breakdown by SOD, CAT, APX, and other peroxidases (POXs), and antioxidants by small molecules, such as glutathione (GSH), ascorbate acid (AsA), phenolic substances, flavonoids, and carotenoids (Pan et al, 2020 ).…”
Section: Discussionmentioning
confidence: 99%
“…Moreover, JPT10 may support osmotic equilibrium in foxtail millet seedlings during salt stress. PGPBs protect plants from salt stress damage through osmotic adjustment (de Andrade et al, 2023 ; Giannelli et al, 2023 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Ramasamy & Mahawar, 2023 ). The bacterial regulation of the concentration of trehalose, proline, and other osmolytes in plants is one of the mechanisms behind induced plant tolerance to desiccation (Ali & Khan, 2021 ; Sandhya et al, 2010 ; Yang et al, 2010 ).…”
Section: Discussionmentioning
confidence: 99%
“…In addition, hormone production is another important mechanism for PGPBs to protect plants against salt stress (de Andrade et al, 2023 ; Giannelli et al, 2023 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Ramasamy & Mahawar, 2023 ). Our findings support the notion that ABA influence the response to salt stress in foxtail millet since the elevated levels of them were caused by the combination of JPT10 and salt stress rather than salt stress alone (Figure 4b ).…”
Plant growth‐promoting bacterias (PGPBs) can increase crop output under normal and abiotic conditions. However, the mechanisms underlying the plant salt tolerance‐promoting role of PGPBs still remain largely unknown. In this study, we demonstrated that Halomonas ventosae JPT10 promoted the salt tolerance of both dicots and monocots. Physiological analysis revealed that JPT10 reduced reactive oxygen species accumulation by improving the antioxidant capability of foxtail millet seedlings. The metabolomic analysis of JPT10‐inoculated foxtail millet seedlings led to the identification of 438 diversely accumulated metabolites, including flavonoids, phenolic acids, lignans, coumarins, sugar, alkaloids, organic acids, and lipids, under salt stress. Exogenous apigenin and chlorogenic acid increased the salt tolerance of foxtail millet seedlings. Simultaneously, JPT10 led to greater amounts of abscisic acid (ABA), indole‐3‐acetic acid (IAA), salicylic acid (SA), and their derivatives but lower levels of 12‐oxo‐phytodienoic acid (OPDA), jasmonate (JA), and JA‐isoleucine (JA‐Ile) under salt stress. Exogenous JA, methyl‐JA, and OPDA intensified, whereas ibuprofen or phenitone, two inhibitors of JA and OPDA biosynthesis, partially reversed, the growth inhibition of foxtail millet seedlings caused by salt stress. Our results shed light on the response of foxtail millet seedlings to H. ventosae under salt stress and provide potential compounds to increase salt tolerance in foxtail millet and other crops.
“…It has been reported that PGPBs protect plants through increasing the antioxidant ability (Ali et al, 2021 ; Giannelli et al, 2023 ; Gururani et al, 2013 ; Jaleel et al, 2007 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Singh et al, 2020 ). Plants have evolved two key defense mechanisms against the accumulation of excessive ROS: enzymatic breakdown by SOD, CAT, APX, and other peroxidases (POXs), and antioxidants by small molecules, such as glutathione (GSH), ascorbate acid (AsA), phenolic substances, flavonoids, and carotenoids (Pan et al, 2020 ).…”
Section: Discussionmentioning
confidence: 99%
“…Moreover, JPT10 may support osmotic equilibrium in foxtail millet seedlings during salt stress. PGPBs protect plants from salt stress damage through osmotic adjustment (de Andrade et al, 2023 ; Giannelli et al, 2023 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Ramasamy & Mahawar, 2023 ). The bacterial regulation of the concentration of trehalose, proline, and other osmolytes in plants is one of the mechanisms behind induced plant tolerance to desiccation (Ali & Khan, 2021 ; Sandhya et al, 2010 ; Yang et al, 2010 ).…”
Section: Discussionmentioning
confidence: 99%
“…In addition, hormone production is another important mechanism for PGPBs to protect plants against salt stress (de Andrade et al, 2023 ; Giannelli et al, 2023 ; Kumar et al, 2021 ; Kumawat et al, 2022 ; Ramasamy & Mahawar, 2023 ). Our findings support the notion that ABA influence the response to salt stress in foxtail millet since the elevated levels of them were caused by the combination of JPT10 and salt stress rather than salt stress alone (Figure 4b ).…”
Plant growth‐promoting bacterias (PGPBs) can increase crop output under normal and abiotic conditions. However, the mechanisms underlying the plant salt tolerance‐promoting role of PGPBs still remain largely unknown. In this study, we demonstrated that Halomonas ventosae JPT10 promoted the salt tolerance of both dicots and monocots. Physiological analysis revealed that JPT10 reduced reactive oxygen species accumulation by improving the antioxidant capability of foxtail millet seedlings. The metabolomic analysis of JPT10‐inoculated foxtail millet seedlings led to the identification of 438 diversely accumulated metabolites, including flavonoids, phenolic acids, lignans, coumarins, sugar, alkaloids, organic acids, and lipids, under salt stress. Exogenous apigenin and chlorogenic acid increased the salt tolerance of foxtail millet seedlings. Simultaneously, JPT10 led to greater amounts of abscisic acid (ABA), indole‐3‐acetic acid (IAA), salicylic acid (SA), and their derivatives but lower levels of 12‐oxo‐phytodienoic acid (OPDA), jasmonate (JA), and JA‐isoleucine (JA‐Ile) under salt stress. Exogenous JA, methyl‐JA, and OPDA intensified, whereas ibuprofen or phenitone, two inhibitors of JA and OPDA biosynthesis, partially reversed, the growth inhibition of foxtail millet seedlings caused by salt stress. Our results shed light on the response of foxtail millet seedlings to H. ventosae under salt stress and provide potential compounds to increase salt tolerance in foxtail millet and other crops.
“…As a result of the inconsistent characteristics of PGPRs, such as the ability of a PGPR to colonize the plant rhizosphere and the ability of bacterial strains to thrive under different environmental conditions, PGPR use in the agriculture industry represents only a small fraction of PGPR use worldwide [ 13 ]. The successful utilization of PGPRs is dependent on several factors, such as their survival in soil and growth-promoting properties [ 14 , 15 ].…”
Plant rhizosphere microorganisms play an important role in modulating plant growth and productivity. This study aimed to elucidate the diversity of rhizosphere microorganisms at the flowering and fruiting stages of rapeseed (Brassica napus). Microbial communities in rhizosphere soils were analyzed via high-throughput sequencing of 16S rRNA for bacteria and internal transcribed spacer (ITS) DNA regions for fungi. A total of 401 species of bacteria and 49 species of fungi in the rhizosphere soil samples were found in three different samples. The composition and diversity of rhizosphere microbial communities were significantly different at different stages of rapeseed growth. Plant-growth-promoting rhizobacteria (PGPRs) have been widely applied to improve plant growth, health, and production. Thirty-four and thirty-one PGPR strains were isolated from the rhizosphere soil samples collected at the flowering and fruiting stages of rapeseed, respectively. Different inorganic phosphorus- and silicate-solubilizing and auxin-producing capabilities were found in different strains, in addition to different heavy-metal resistances. This study deepens the understanding of the microbial diversity in the rapeseed rhizosphere and provides a microbial perspective of sustainable rapeseed cultivation.
“…In addition, PGPR are essential in mitigating the adverse effects of salinity and drought stress on plants 24 . By improving beneficial interactions with plant roots, these bacteria enhance the plant's ability to withstand harsh environmental conditions, making them invaluable in promoting crop resilience in saline and arid regions 25 , 26 . Figure 1 Direct and indirect mechanisms of PGPR in enhancing plant growth and health.…”
Plant growth promoting rhizobacteria are a diverse group of microorganisms that enhance the growth of plants under various conditions. In this study, 55 isolates of endogenous rhizobacteria were collected from the rhizosphere of Avicennia marina, Suaeda vermiculata, Salsola soda, Anabasis setifera, Salicornia europaea, Arthrocnemum macrostachyum, Limonium axillare, Tetraena qatarensis, Aeluropus lagopoides, and Prosopis juliflora. The isolates were evaluated in-vitro for their antagonist potential against Fusarium oxysporum and Botrytis cinerea using the dual culture technique, where the maximum growth inhibition reached 49% and 57%, respectively. In-vivo evaluation was accomplished to determine the growth-promoting potential of the rhizobacteria under greenhouse conditions where the strain ANABR3 (Bacillus subtilis) showed the strongest growth-promoting effects. Further in-vivo testing regarding the effectiveness of rhizobacteria in the presence of the phytopathogen was also completed using the Hoagland medium. LEMR3 and SALIR5 (both identified as two strains of B. subtilis) supported the tomato seedlings to overcome the disease and significantly (p ≤ 0.05) increased above and belowground biomass compared to the control. Additionally, several characterizing tests were carried out on the selected strains, these strains were found to possess numerous features that promote plant growth directly and indirectly such as the production of IAA, HCN, hydrolytic enzymes, ACC deaminase, NH3, and some rhizobacteria were capable of phosphate solubilization. In conclusion, this study showed that local rhizobacterial isolates collected from arid lands possess valuable traits, making them promising bio-control agents and bio-fertilizers for agricultural purposes.
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