Diversity and Plant Growth-Promoting Ability of Endophytic, Halotolerant Bacteria Associated with Tetragonia tetragonioides (Pall.) Kuntze.

Dilfuza Egamberdieva,Vyacheslav Shurigin,Stephan Wirth,Sonoko Dorothea Bellingrath-Kimura,Jakhongir Alimov,Burak Alaylar

doi:10.3390/plants11010049

Abstract

The diversity of salt-tolerant cultivable endophytic bacteria associated with the halophyte New Zealand spinach (Tetragonia tetragonioides (Pall.) Kuntze) was studied, and their plant beneficial properties were evaluated. The bacteria isolated from leaves and roots belonged to Agrobacterium, Stenotrophomonas, Bacillus, Brevibacterium, Pseudomonas, Streptomyces, Pseudarthrobacter, Raoultella, Curtobacterium, and Pantoea. Isolates exhibited plant growth-promoting traits, including the production of a phytohormone (indole 3-acetic-acid), cell wall degrading enzymes, and hydrogen cyanide production. Furthermore, antifungal activity against the plant pathogenic fungi Fusarium solani, F. oxysporum, and Verticillium dahliae was detected. Ten out of twenty bacterial isolates were able to synthesize ACC deaminase, which plays a vital role in decreasing ethylene levels in plants. Regardless of the origin of isolated bacteria, root or leaf tissue, they stimulated plant root and shoot growth under 200 mM NaCl conditions. Our study suggests that halophytes such as New Zealand spinach are a promising source for isolating halotolerant plant-beneficial bacteria, which can be considered as potentially efficient biofertilizers in the bioremediation of salt-affected soils.

Highlights

IntroductionSoil salinity is one of the most severe abiotic factors that degrade agricultural land with substantial detrimental effects on plant growth and yield losses worldwide
Only ten isolates of endophytic bacteria were left from roots and ten isolates from leaves
Numerous reports have already been published on the diversity of salt-tolerant plant beneficial bacteria, including various species belonging to Acetobacter, Azospirillum, Arthrobacter, Bacillus, Pseudomonas, Rhizobium, Serratia, and Steretrophomonas [27,28]

Summary

Introduction

Soil salinity is one of the most severe abiotic factors that degrade agricultural land with substantial detrimental effects on plant growth and yield losses worldwide. It is known that halophytes hold potential for the bioremediation of salt-affected land and for restoring or improving soil productivity [5,6]. Halophytes withstand salt stress by producing compatible solutes and regulating stress-responsive genes, modulating reactive oxygen species, and drawing benefits from their associated microbes [7,8]. There are numerous reports on the diversity of halotolerant bacterial species of genera such as Acetobacter, Azospirillum, Arthrobacter, Bacillus, Pseudomonas, Pantoea, Rhizobium, Serratia, Streptomyces, and Steretrophomonas associated with halophytes such as Salicornia bigelovii [13], Halocnemum strobilaceum [14], Seidlitzia rosmarinus [15], Salicornia brachiate [16], or Haloxylon ammodendron [17]

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