Identification of Salt-tolerant Plant Growth-promoting Bacterium W-1 and Its Effect on the Salt-tolerance of Sainfoin（Onobrychis viciaefolia）

doi:10.13560/j.cnki.biotech.bull.1985.2023-0905

Abstract

Abstract:

【Objective】To obtain salt-tolerant plant growth-promoting bacteria, several strains of salt-tolerant bacteria were isolated from plant roots in a saline-alkali soil in Jingtai, Gansu province, and some of them had obvious plant growth-promoting characteristics.【Method】Based on the previous work, a strain of salt-tolerant bacterium W-1 and a salt-sensitive plant sainfoin（Onobrychis viciaefolia）were selected as experimental materials, and the species classification, salt tolerance, acid and alkali tolerance and plant growth-promoting characteristics of strain W-1 were tested. The effects of strain W-1 on the physiological status of sainfoin treated with different concentrations of NaCl were investigated. 【Result】The salt-tolerant bacterium W-1 was Gram-positive, spore-producing, without capsule and flagellated. The 16S rDNA sequencing and comparison results showed that the bacterium W-1 was Bacillus siamensis. The maximum NaCl tolerance of strain W-1 was 13%, and the pH tolerance range was 4.5-8.5. W-1 has various plant growth-promoting functions, such as phosphate and potassium solubilization, nitrogen fixation, siderophores production, indole-3-acetic acid（IAA）production and 1-aminocyclopropane-1-carboxylic acid（ACC）deaminase activity. Strain W-1 significantly increased dry weight and fresh weight and promoted root growth of sainfoin seedlings. Under 100 and 150 mmol/L NaCl stresses, strain W-1 significantly increased the contents of soluble sugar, soluble protein, proline, chlorophyll, and catalase activity, decreased the content of hydrogen peroxide, leaf yellowing rate and mortality, and alleviated the adverse effects of salt stress on the growth of sainfoin seedlings.【Conclusion】The W-1 strain was an excellent plant growth- promoting bacterium with salt tolerance, acid and alkali tolerance, and enhanced the salt tolerance of legume forage.

Key words: plant growth-promoting bacteria, indole-3-acetic acid, nitrogen fixation, phosphate solubilization, ACC-deaminase, salt stress

GAO Zhi-wei, WEI Ming, YU Zu-long, WU Guo-qiang, WEI Jun-long. Identification of Salt-tolerant Plant Growth-promoting Bacterium W-1 and Its Effect on the Salt-tolerance of Sainfoin（Onobrychis viciaefolia）[J]. Biotechnology Bulletin, 2024, 40(4): 217-227.

Figures/Tables 9

Fig. 1 16S rDNA phylogenetic tree of strain W-1

Fig. 2 Strain W-1 staining A: Gram staining. B: Endospore staining（The green dots are endospores）. C: Capsule staining. D: Flagellum staining（The red arrow points to light filaments as flagella）（100×）

Fig. 3 Effects of NaCl（A）and pH（B）on the growth of strain W-1 The numbers in the legend in Fig. A and B represent NaCl concentration and pH in the medium, respectively. The error line refers to the standard deviation（n=3）

Fig. 4 Detection of plant growth-promoting characteristics of strain W-1 A: IAA color development reaction; B: phosphate solubilization color development reaction; C: phosphate solubilization, potassium solubilization, nitrogen fixation, siderophore. The numbers in Fig. A and B indicate IAA and P concentrations（mg/L）; “-W-1” indicates the unvaccinated strain W-1, and “+ W-1” indicates the vaccinated strain W-1, the same below

Fig. 5 Effects of inoculation on the seedling development of 4 d-old（A）, 12 d-old（B）and 14 d-old（C）sainfoin under different degrees of NaCl stress

Fig. 6 Effects of inoculation with W-1 on the fresh weight, dry weight and water content of 14-day-old sainfoin seedlings treated with different concentrations of NaCl The error line refers to the standard deviation（n=3）. The lowercase letters indicate that the difference among different treatment at significant level（P< 0.05）. The same below

Fig. 7 Effects of inoculated W-1 on the seedling growth of sainfoin under different concentration of NaCl

Fig. 8 Effects of inoculation with W-1 on the leaf number, leaf withering rate and fresh weights of sainfoin under different concentrations of NaCl

Fig. 9 Effects of inoculation with W-1 on the contents of soluble protein, soluble sugar, proline, total chlorophyll, CAT and H2O2 in sainfoin seedlings under different concentrations of NaCl

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