Identification of interior salt-tolerant bacteria from ice plant Mesembryanthemum crystallinum and evaluation of their promoting effects
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Endophytic bacteria can stimulate host plant development. Insufficient information is available about NaCl-tolerant bacteria that colonize ice plants (Mesembryanthemum crystallinum) in their habitats. In this study, a culture-dependent method was used to isolate endophytic nitrogen-fixing bacteria from ice plants, and the resulting cultures were screened for salt-stress tolerance in vitro. A total of 17 salt-tolerant bacteria were obtained. The majority of the isolates grew well in 2.05 M NaCl with a maximum tolerance at 3.59 M. Most of the strains were Gram-positive bacteria with various plant growth-promoting traits. The 16S rRNA gene sequences revealed that the 17 isolates were distributed within three genera and corresponded to the bacterial species Halomonas sp., Bacillus sp., and Planococcus sp. Inoculation of cabbage (Brassica olereacea) seeds with selected strains showed that the strain MC1 promoted seed germination, and the same strain significantly increased root dry weight under saline stress by 24.5%. Our study suggests that ice plants naturally accommodate a variety of salt-tolerant endophytic bacteria and that these bacteria are able to relieve abiotic stress during plant growth.
KeywordsSalt-tolerance Nitrogen-fixing bacteria Ice plant Vegetable crop Saline condition
This work was financially supported by the National Natural Science Foundation of China (Grant No.31701968), the Anhui Science and Technology Project (1704a07020078), the Dean’s Youth Innovation Project (17B0307), and the Vegetable Cultivation Scientific Innovation Team (18C0309) from Anhui Academy of Agricultural Sciences. We gratefully acknowledge two anonymous referees and editors who provided valuable and constructive suggestions to improve this manuscript.
ZJ and WPC planed and designed the research. ZJ, WPC, WY, JHK, and YCS performed the experiments. ZJ, WPC, and THM analyzed the data. ZJ, WPC, WY, and THM wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors have declared that no competing interests exist.
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