Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress
Alfalfa (<i>Medicago sativa</i> L.), a forage legume known for its moderate salt–alkali tolerance, offers notable economic and ecological benefits and aids in soil amelioration when cultivated in saline–alkaline soils. Nonetheless, the limited stress resistance of alfalfa could curtail i...
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MDPI AG
2024-03-01
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| Series: | Microorganisms |
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| author | Xixi Ma Cuihua Huang Jun Zhang Jing Pan Qi Guo Hui Yang Xian Xue |
| author_facet | Xixi Ma Cuihua Huang Jun Zhang Jing Pan Qi Guo Hui Yang Xian Xue |
| author_sort | Xixi Ma |
| collection | DOAJ |
| description | Alfalfa (<i>Medicago sativa</i> L.), a forage legume known for its moderate salt–alkali tolerance, offers notable economic and ecological benefits and aids in soil amelioration when cultivated in saline–alkaline soils. Nonetheless, the limited stress resistance of alfalfa could curtail its productivity. This study investigated the salt tolerance and growth-promoting characteristics (in vitro) of four strains of plant growth-promoting rhizobacteria (PGPR) that were pre-selected, as well as their effects on alfalfa at different growth stages (a pot experiment). The results showed that the selected strains belonged to the genera <i>Priestia</i> (HL3), <i>Bacillus</i> (HL6 and HG12), and <i>Paenibacillus</i> (HG24). All four strains exhibited the ability to solubilize phosphate and produce indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Among them, except for strain HG24, the other strains could tolerate 9% NaCl stress. Treatment with 100 mM NaCl consistently decreased the IAA production levels of the selected strains, but inconsistent changes (either enhanced or reduced) in terms of phosphate solubilization, ACC deaminase, and exopolysaccharides (EPS) production were observed among the strains. During the various growth stages of alfalfa, PGPR exhibited different growth-promoting effects: at the seedling stage, they enhanced salt tolerance through the induction of physiological changes; at the flowering stage, they promoted growth through nutrient acquisition. The current findings suggest that strains HL3, HL6, and HG12 are effective microbial inoculants for alleviating salt stress in alfalfa plants in arid and semi-arid regions. This study not only reveals the potential of indigenous salt-tolerant PGPR in enhancing the salt tolerance of alfalfa but also provides new insights into the mechanisms of action of PGPR. |
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| series | Microorganisms |
| spelling | doaj.art-f2f21d8dc234490a861bdf879942b7e02024-03-27T13:56:00ZengMDPI AGMicroorganisms2076-26072024-03-0112361610.3390/microorganisms12030616Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt StressXixi Ma0Cuihua Huang1Jun Zhang2Jing Pan3Qi Guo4Hui Yang5Xian Xue6Drylands Salinization Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, ChinaDrylands Salinization Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, ChinaInstitute of Biology, Gansu Academy of Sciences, Lanzhou 730000, ChinaDrylands Salinization Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, ChinaInstitute of Biology, Gansu Academy of Sciences, Lanzhou 730000, ChinaInstitute of Biology, Gansu Academy of Sciences, Lanzhou 730000, ChinaDrylands Salinization Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, ChinaAlfalfa (<i>Medicago sativa</i> L.), a forage legume known for its moderate salt–alkali tolerance, offers notable economic and ecological benefits and aids in soil amelioration when cultivated in saline–alkaline soils. Nonetheless, the limited stress resistance of alfalfa could curtail its productivity. This study investigated the salt tolerance and growth-promoting characteristics (in vitro) of four strains of plant growth-promoting rhizobacteria (PGPR) that were pre-selected, as well as their effects on alfalfa at different growth stages (a pot experiment). The results showed that the selected strains belonged to the genera <i>Priestia</i> (HL3), <i>Bacillus</i> (HL6 and HG12), and <i>Paenibacillus</i> (HG24). All four strains exhibited the ability to solubilize phosphate and produce indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Among them, except for strain HG24, the other strains could tolerate 9% NaCl stress. Treatment with 100 mM NaCl consistently decreased the IAA production levels of the selected strains, but inconsistent changes (either enhanced or reduced) in terms of phosphate solubilization, ACC deaminase, and exopolysaccharides (EPS) production were observed among the strains. During the various growth stages of alfalfa, PGPR exhibited different growth-promoting effects: at the seedling stage, they enhanced salt tolerance through the induction of physiological changes; at the flowering stage, they promoted growth through nutrient acquisition. The current findings suggest that strains HL3, HL6, and HG12 are effective microbial inoculants for alleviating salt stress in alfalfa plants in arid and semi-arid regions. This study not only reveals the potential of indigenous salt-tolerant PGPR in enhancing the salt tolerance of alfalfa but also provides new insights into the mechanisms of action of PGPR.https://www.mdpi.com/2076-2607/12/3/616PGPRsaline–alkali soilphosphate solubilizationindole-3-acetic acid (IAA)1-aminocyclopropane-1-carboxylic (ACC) deaminasesalt tolerance |
| spellingShingle | Xixi Ma Cuihua Huang Jun Zhang Jing Pan Qi Guo Hui Yang Xian Xue Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress Microorganisms PGPR saline–alkali soil phosphate solubilization indole-3-acetic acid (IAA) 1-aminocyclopropane-1-carboxylic (ACC) deaminase salt tolerance |
| title | Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress |
| title_full | Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress |
| title_fullStr | Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress |
| title_full_unstemmed | Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress |
| title_short | Comparative Analysis of Plant Growth-Promoting Rhizobacteria’s Effects on Alfalfa Growth at the Seedling and Flowering Stages under Salt Stress |
| title_sort | comparative analysis of plant growth promoting rhizobacteria s effects on alfalfa growth at the seedling and flowering stages under salt stress |
| topic | PGPR saline–alkali soil phosphate solubilization indole-3-acetic acid (IAA) 1-aminocyclopropane-1-carboxylic (ACC) deaminase salt tolerance |
| url | https://www.mdpi.com/2076-2607/12/3/616 |
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