Deep-Sea Actinobacteria Mitigate Salinity Stress in Tomato Seedlings and Their Biosafety Testing.

Pharada Rangseekaew,Maximino Manzanera,Wasu Pathom-Aree,Adoración Barros-Rodríguez

doi:10.3390/plants10081687

Pharada Rangseekaew, Maximino Manzanera + Show 2 more

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https://doi.org/10.3390/plants10081687

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Abstract

Soil salinity is an enormous problem affecting global agricultural productivity. Deep-sea actinobacteria are interesting due to their salt tolerance mechanisms. In the present study, we aim to determine the ability of deep-sea Dermacoccus (D. barathri MT2.1T and D. profundi MT2.2T) to promote tomato seedlings under 150 mM NaCl compared with the terrestrial strain D. nishinomiyaensis DSM20448T. All strains exhibit in vitro plant growth-promoting traits of indole-3-acetic acid production, phosphate solubilization, and siderophore production. Tomato seedlings inoculated with D. barathri MT2.1T showed higher growth parameters (shoot and root length, dry weight, and chlorophyll content) than non-inoculated tomato and the terrestrial strain under 150 mM NaCl. In addition, hydrogen peroxide (H2O2) in leaves of tomatoes inoculated with deep-sea Dermacoccus was lower than the control seedlings. This observation suggested that deep-sea Dermacoccus mitigated salt stress by reducing oxidative stress caused by hydrogen peroxide. D. barathri MT2.1T showed no harmful effects on Caenorhabditis elegans, Daphnia magna, Eisenia foetida, and Escherichia coli MC4100 in biosafety tests. This evidence suggests that D. barathri MT2.1T would be safe for use in the environment. Our results highlight the potential of deep-sea Dermacoccus as a plant growth promoter for tomatoes under salinity stress.

Highlights

Marine ecosystems cover more than 70% of the surface of the Earth, with most parts still under-explored [1]
We have shown that the survival rate of E. coli MC4100 exposed to supernatants from two marine actinobacteria, D. barathri MT2.1T and D. profundi MT2.2T was similar to the rate of non-pathogenic P. putida KT2440
In conclusion, our results clearly show that deep-sea, D. barathri MT2.1T could promote the growth of tomato (Solanum lycopersicum) seedlings under salinity stress

Summary

Introduction

Marine ecosystems cover more than 70% of the surface of the Earth, with most parts still under-explored [1]. Actinobacteria are widely distributed in deep-sea environments [2,3,4]. These marine actinobacteria are considered an excellent source of bioactive compounds. The deep-sea environment is generally characterized by high pressure, low temperature, lack of light with varying concentrations of oxygen and salinity [2,5]. Deep-sea actinobacteria have to adapt or develop unique abilities to withstand salinity and pressure [6] or piezotolerant properties [7] to survive under these extreme conditions. With the adaptive ability to survive under extreme environments, especially salinity and osmotic stress, these deep-sea actinobacteria are likely to be useful as biostimulants to mitigate salinity stress for plant growth

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