Abstract
PurposeSalt stress reduces plant growth and is now becoming one of the most important factors restricting the agricultural productivity. Inoculation of plant growth-promoting rhizobacteria (PGPR) has been shown to confer plant tolerance against abiotic stress, but the detailed mechanisms of how this occurs remain unclear and the application effects in different reports are unstable. In order to obtain a favorite effect of PGPR inoculation and improve our knowledge about the related mechanism, we performed this study to analyze the mechanism of a PGPR consortium on improving the salt resistance of crops.MethodsA region-specific (Saline land around Bohai Sea in China) PGPR consortium was selected that contains three strains (Pseudomonas sp. P8, Peribacillus sp. P10, and Streptomyces sp. X52) isolated from rhizosphere of Sonchus brachyotus DC. grown in a saline soil. By inoculation tests, their plant growth-promoting (PGP) traits and ability to improve the salt resistance of maize were investigated and shifting in rhizosphere bacterial community of the inoculated plants was analyzed using the high-throughput sequencing technology.ResultsThe three selected strains were salt tolerant, presented several growth promoting properties, and inhibited several phytopathogenic fungi. The inoculation of this consortium promoted the growth of maize plant and enriched the beneficial bacteria in rhizosphere of maize in a saline soil, including the nitrogen fixing bacteria Azotobacter, Sinorhizobium, and Devosia, and the nitrification bacteria Candidatus Nitrososphaera, and Nitrosovibrio.ConclusionsThe bacterial consortium P8/P10/X52 could improve plant growth in a saline soil by both their PGP traits and regulating the rhizosphere bacterial community. The findings provided novel information about how the PGPR helped the plants in the view of microbiome.
Highlights
Soil salinity is a common problem and one of the main abiotic stress factors that inhibit plant growth and development (Egamberdieva et al 2019)
The production of Indole-3-acetic acid (IAA) was determined by the method of Khalid et al 2004 and Bric et al 1991; the production of 1aminocyclopropane-1-carboxylic acid deaminase (ACCD) (1-aminocyclopropane-1-carboxylic acid deaminase) was determined by the method of Penrose and Glick 2003]; the production of siderophores was estimated based on the work of Schwyn and Neilands 1987; phosphate solubilization potential was determined by the method of Vyas et al 2007; and nitrogen fixation capacity was investigated using the method of Dobereiner et al 1976
Based on the plant growth-promoting (PGP) traits (Table 1), three isolates P8, P10, and X52 were able to grow in the presence of 5% and 10% (w/v) NaCl were selected for constructing the consortium
Summary
Soil salinity is a common problem and one of the main abiotic stress factors that inhibit plant growth and development (Egamberdieva et al 2019). Salinization refers to the concentration increase or accumulation of watersoluble salts in soil. As the most important type of soil degradation, soil salinization seriously affects crop production mainly by decreasing the osmotic potential of the soil that makes the plants difficult to absorb water, and by the direct toxic of salts. With the human activity in arable land, such as excessive and long term supply of chemical fertilizers, the degree of secondary salinization of soil becomes more and more serious. Soil salinization forms a limitation to fit the increased food demand companied with the development of human society and the increase of population
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