Salt-tolerant endophytic bacterium Enterobacter ludwigii B30 enhance bermudagrass growth under salt stress by modulating plant physiology and changing rhizosphere and root bacterial community

Abstract

Osmotic and ionic induced salt stress suppresses plant growth. In a previous study, Enterobacter ludwigii B30, isolated from Paspalum vaginatum, improved seed germination, root length, and seedling length of bermudagrass (Cynodon dactylon) under salt stress. In this study, E. ludwigii B30 application improved fresh weight and dry weight, carotenoid and chlorophyll levels, catalase and superoxide dismutase activities, indole acetic acid content and K+ concentration. Without E. ludwigii B30 treatment, bermudagrass under salt stress decreased malondialdehyde and proline content, Y(NO) and Y(NPQ), Na+ concentration, 1-aminocyclopropane-1-carboxylate, and abscisic acid content. After E. ludwigii B30 inoculation, bacterial community richness and diversity in the rhizosphere increased compared with the rhizosphere adjacent to roots under salt stress. Turf quality and carotenoid content were positively correlated with the incidence of the phyla Chloroflexi and Fibrobacteres in rhizosphere soil, and indole acetic acid (IAA) level was positively correlated with the phyla Actinobacteria and Chloroflexi in the roots. Our results suggest that E. ludwigii B30 can improve the ability of bermudagrass to accumulate biomass, adjust osmosis, improve photosynthetic efficiency and selectively absorb ions for reducing salt stress-induced injury, while changing the bacterial community structure of the rhizosphere and bermudagrass roots. They also provide a foundation for understanding how the bermudagrass rhizosphere and root microorganisms respond to endophyte inoculation.

Turfgrass Salinity Stress and Tolerance—A Review

“…In addition, future research should include a recovery component after salinity stress to provide more details for consumers regarding a specific turfgrass cultivar’s recuperative capacity to salinity stress. As prior studies have indicated, exogenous applications of various chemical products such as PGRs, silicon, various external applicants ( Table 3 ), and even biological agents have elevated abiotic stress resistance and improved carbohydrate metabolism while under stress for many salt-sensitive turfgrass species [ 108 , 123 , 127 ]. There is still a need for further research on optimal turfgrass nutrition and nutrition homeostasis before and during salinity stress.…”

“…Both fungal and bacterial endophytes typically colonize and live within an individual host plant throughout its life cycle without causing any significant parasitic symptoms as symbiotic relationships. Among turfgrasses, several species have been identified to mitigate salinity stresses [ 127 ]. The mechanisms are highly related to the host plant water and nutrient uptake, and enhanced plant hormone productions to minimize salinity, drought, and heat stresses.…”

“…The salt-tolerant bacterium Enterobacter ludwigii B30 was isolated from Paspalum vaginatum . A salt tolerance test showed that B30 could grow normally in a 500 mM NaCl medium [ 127 ].…”

Exploring the potential of halotolerant bacteria from coastal regions to mitigate salinity stress in wheat: physiological, molecular, and biochemical insights

“…In early Studies numerous plant species have been treated with endophytic bacteria to reduce salt stress ( Pal et al., 2021 ; Sofy et al., 2021 ). Similarly, the inoculation of E. ludwigii B30 improved plant growth in both non-salt stress and salt stress environments, as evidenced by higher shoot height, root length, and shoot and root biomass ( Wei et al., 2022 ). The antioxidative enzymes produced by PGPB or the expression of plant genes involved in the synthesis of ROS-scavengers can both help plants recover from oxidative stress.…”

The Potential of Endophytes in Improving Salt–Alkali Tolerance and Salinity Resistance in Plants

“…Similar results were obtained by other researchers who used the salt-tolerant endophytic bacterium Enterobacter ludwigii B30 to increase fresh and dry weights; carotenoid and chlorophyll contents; catalase and superoxide dismutase activities; indoleacetic acid contents; and K + concentration. Without the E. Ludwigii B30 treatment, the malondialdehyde, proline, PSII [Y (NO) and Y (NPQ)], 1-aminocyclopropane-1-carboxylic acid, and abscisic acid contents of dogbanes decreased under salt stress [85].…”