MICROBIOME OF THE HALOPHYTE HORDEUM HYSTRIX ROTH. AS A SOURCE OF THE HALOPHILIC PGP BACTERIA

Abstract

BACKGROUND Determination of the halophytic microbiome diversity is the basis for understanding the mechanisms that enable halophytes to tolerate the increased salt concentration. This report provides new data regarding the bacterial halophyte community and diversity of the endorhizosphere of the halophytic Hordeum hystrix Roth. Hordeum hystrix Roth. (Poaceae) is an annual plant of seasonally flooded saline lands and consequently, plant samples were collected from the area of the naturally formed saline lands, Slano Kopovo.

OBJECTIVES In addition to the analysis of microbiome diversity, the aim of this study was to characterize isolates of halophilic endophytic bacteria and their plant growth promoting ability. METHODS The metagenomic approach based on 16s rRNA gene sequencing was used to gain insight into the composition of the endophyte bacterial community at different taxonomic levels. The endophytic isolates were initially selected for the maximum salt concentration tolerance and the ability to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase. Selected strains were tested on eight PGP traits at different NaCl concentrations. RESULTS Most isolates could tolerate the NaCl concentration over a range from 3-20%. Two strains showed positive results related to all eight tested PGP traits. At the high NaCl concentrations, the same strains retained seven positive PGP features. Our results indicate that the endorhizosphere of the halophytes is a source of halophilic PGP bacteria that, in addition to its beneficial effects on the host, have the possibility of their potential application in sustainable agriculture.