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. 2024 Sep 9:3:76.
doi: 10.12688/openreseurope.15821.4. eCollection 2023.

Using halotolerant Azotobacter chroococcum W4ii from technosoils to mitigate wheat salt stress

Sweta Binod Kumar  1 , Agnieszka Kalwasińska  1 , Maria Swiontek Brzezinska  1 , Monika Wróbel  1
Affiliations

Using halotolerant Azotobacter chroococcum W4ii from technosoils to mitigate wheat salt stress

Sweta Binod Kumar et al. Open Res Eur. .

Abstract

Background: Technosoils in Inowrocław, central Poland, are impacted by human activities and exhibit high salinity (ECe up to 70 dS/m) due to a soda lime repository. These saline environments pose challenges to plant growth and soil health. However, they also offer an opportunity for the evolution of microorganisms adapted to such conditions, including plant growth-promoting rhizospheric (PGPR) bacteria. The hypothesis tested here was that introducing PGPR bacteria from these environments could boost degraded soil performance, leading to better plant biomass and improved pathogen defense.

Methods: Azotobacter chroococcum W4ii was isolated from the rhizosphere of wheat ( Triticum aestivum L.) for its plant growth properties on wheat plants under salt stress.

Results: Wheat seeds co-inoculated with A. chroococcum W4ii under 200 mM salt stress showed significant improvement in various growth parameters such as seeds germination (by 130%), shoot biomass (15%), chlorophyll b content (40%) compared to un-inoculated ones. Bacterial inoculation decreased the level of malondialdehyde (MDA) by 55.5% (P<0.001), whereas it elevated the antioxidative enzymatic activities of peroxidase (POD) by 33.69% (P<0.001). The test isolate also significantly (P<0.05) enhanced the level of defense enzymes like β-1,3-glucanase, which can protect plants from infection by pathogens. The bacterium could also successfully colonize the wheat plants.

Conclusions: These results indicate that A. chroococcum isolated from the technosoil has the potential to promote wheat growth under salt stress and can be further used as a bioinoculant in the salt affected agricultural fields.

Keywords: Azotobacter chroococcum; PGPR; Salt stress; Technosoil; Triticum aestivum L..

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Conflict of interest statement

No competing interests were disclosed.

Figures

Figure 1.
Figure 1.. Effect of salinity on plant growth in the sand.
Each data represent the mean ± SD of triplicate sets of five measurements (n = 15). Different letters on the bar in each column represent the significant difference.
Figure 2.
Figure 2.. Effect of salinity on plant biomass in the sand.
Each data represent the mean ± SD of five plants in triplicate sets (n = 3). Different letters on the bar in each column represent the significant difference.
Figure 3.
Figure 3.. Effect of inoculation of A. chroococcum W4ii on plant growth in the sand under 0 mM NaCl and 200 mM NaCl.
Each data represent the mean ± SD (n = 15). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 4.
Figure 4.. Effect of inoculation of A. chroococcum W4ii on plant shoot weight in the sand under 200 mM NaCl.
Each data represent the mean ± SD of 5 plants in triplicate sets (n = 3). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 5.
Figure 5.. Seed germination in the sand.
Each data represent the mean ± SD (n = 3). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 6.
Figure 6.. Effect of inoculation of A. chroococcum W4ii on plant chlorophyll b under 200 mM NaCl in the sand.
Each data represent the mean ± SD (n = 6). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 7.
Figure 7.. Effect of inoculation of A. chroococcum W4ii on plant shoot weight under 200 mM NaCl in soil.
Each data represent the mean ± SD of 10 plants in triplicate sets (n = 3). Different letters on the bar in each column represent the significant difference.
Figure 8.
Figure 8.. Effect of inoculation of A. chroococcum W4ii on plant MDA content under 200 mM NaCl in soil.
Each data represent the median ± IQR (n = 9). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 9.
Figure 9.. Effect of inoculation of A. chroococcum on plant proline content under 200 mM NaCl in soil.
Each data represent the median ± IQR of triplicate sets (n = 3).
Figure 10.
Figure 10.. Effect of inoculation of A. chroococcum W4ii on plant total soluble sugar (TSS) under 200 mM NaCl in soil.
Each data represent the mean ± SD of triplicate sets (n = 3). The same letters on the bar in each column represent no significant difference.
Figure 11.
Figure 11.. Effect of inoculation of A. chroococcum W4ii on plant’s peroxidase activity under 200 mM NaCl in soil.
Each data represent the mean ± SD (n = 9). Different letters on the bar in each column represent the significant difference (P<0.05).
Figure 12.
Figure 12.. Effect of inoculation of A. chroococcum W4ii on root and shoot of plant’s β-1,3-glucanase activity under 200 mM NaCl in soil.
Each data represent the mean ± SD (n = 3). Different letters on the bar in each column represent the significant difference (P<0.05).
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