ENDOPHYTIC BACTERIA OF COMMON TAMARISK (TAMARIX GALLICA L.) AND ALKALI SEEPWEED (SUAEDA FRUTICOSA (L.) FORSSK.) AS POTENTIAL BIOCONTROL AND PLANT GROWTH-PROMOTING AGENTS IN ARID ENVIRONMENTS

Abstract

In this study, fifty-two endophytic halotolerant bacteria from Tamarix gallica L. and Suaeda fruticosa (L.) Forssk. growing in the M'Zab valley (Southern Algeria) were isolated to test their ability to reduce salt stress in barley (Hordeum vulgare L.), and tomato (Solanum lycopersicum L.) seeds. Identification by Gas Chromatography (GC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) confirmed the presence of strains belonging mainly to the genera Bacillus followed by Pseudomonas, Pantoea, Klebsiella and Providencia. All isolates were characterized for their antagonistic activities against some plant pathogenic bacteria and fungi. In addition, isolates were screened for their in vitro plant growth promotion (PGP) abilities, including ACC-deaminase activity, inorganic phosphate solubilization and production of indole-3-acetic acid (IAA), siderophores and lytic enzyme activity. Four isolates that expressed interesting PGP capabilities were tested for their efficacy in modulating salt stress and promoting the growth of barley and tomato seedlings in Petri dish experiments. The strain TE7 showed interesting performances under salt stress for tomato seedlings while strains SE5 and SE19 produced positive results for barley seedlings under normal conditions. The results of this study suggest that endophytic bacteria from natural plants in saline habitats present an interesting source for the isolation of salt-tolerant PGP bacteria that can be used in plant cultivation under normal and saline conditions.