Assessing the role of endophytic bacteria in the halophyte Arthrocnemum macrostachyum salt tolerance

Abstract

There is an increasing interest to use halophytes for revegetation of salt affected ecosystems, as well as in understanding their mechanisms of salt tolerance. We hypothesized that bacteria from the phyllosphere of these plants might play a key role in its high tolerance to excessive salinity. Eight endophytic bacteria belonging to Bacillus and closely related genera were isolated from phyllosphere of the halophyte Arthrocnemum macrostachyum growing in salty agricultural soils. The presence of plant-growth promoting (PGP) properties, enzymatic activities and tolerance towards NaCl was determined. Effects of inoculation on seeds germination and adult plant growth under experimental NaCl treatments (0, 510 and 1030 mM NaCl) were studied. Inoculation with a consortium including the best performing bacteria improved considerably the kinetics of germination and the final germination percentage of A. macrostachyum seeds. At high NaCl concentrations (1030 mM), inoculation of plants mitigated the effects of high salinity on plant growth and physiological performance and, in addition, this consortium appears to have increased the potential of A. macrostachyum to accumulate Na in its shoots, thus improving sodium phytoextraction capacity. Bacteria isolated from A. macrostachyum phyllosphere seem to play an important role in plant salt tolerance under stressing salt concentrations. The combined use of A. macrostachyum and its microbiome can be an adequate tool to enhance plant adaptation and sodium phytoextraction during restoration of salt degraded soils.

The Root Nodule Microbiome of Cultivated and Wild Halophytic Legumes Showed Similar Diversity but Distinct Community Structure in Yellow River Delta Saline Soils

“…Recently, increasing attention has focused on the utilization of microbes to mediate plant salt tolerance [31][32][33]. Previous studies have shown that endophytic bacteria associated with halophytic plants invariably show high salt tolerance and play important roles in the salt tolerance of host plants [34][35][36]. Consistently, Rejili et al reported that rhizobia in the nodules of wild legumes growing in saline soils showed salt tolerance [37].…”

Bacterial Diversity Associated With the Rhizosphere and Endosphere of Two Halophytes: Glaux maritima and Salicornia europaea

“…A large number of reports have shown that halotolerant plant growth-promoting rhizobacteria (PGPRs) isolated from halophytes enhance salt tolerance in their host plants. For example, the salt tolerance of Arthrocnemum macrostachyum is improved by its endophytic bacteria ( Navarro-Torre et al, 2017 ; Tian and Zhang, 2017 ). As another example, in Salicornia strobilacea , rhizospheric bacteria which can stably colonize the rhizoplane are capable of improving plant growth ( Marasco et al, 2016 ).…”

Illumina-Based Analysis of Endophytic and Rhizosphere Bacterial Diversity of the Coastal Halophyte Messerschmidia sibirica

“…A large number of endophytic bacteria from halophytes have been shown the ability to improve salt tolerance of their host plants. For example, Navarro-Torre et al (2017) reported that the endophytic bacteria from Arthrocnemum macrostachyum could improve its salt tolerance. Hashem et al (2016) revealed that the growth promotion effect of endophytic bacteria and arbuscular mycorrhizal fungi (AMF) on Acacia gerrardii under salt stress were associated to a tripartite mutualistic symbiosis in A. gerrardii .…”