Salicornia strobilacea (Synonym of Halocnemum strobilaceum) Grown under Different Tidal Regimes Selects Rhizosphere Bacteria Capable of Promoting Plant Growth

Abstract

Halophytes classified under the common name of salicornia colonize salty and coastal environments across tidal inundation gradients. To unravel the role of tide-related regimes on the structure and functionality of root associated bacteria, the rhizospheric soil of Salicornia strobilacea (synonym of Halocnemum strobilaceum) plants was studied in a tidal zone of the coastline of Southern Tunisia. Although total counts of cultivable bacteria did not change in the rhizosphere of plants grown along a tidal gradient, significant differences were observed in the diversity of both the cultivable and uncultivable bacterial communities. This observation indicates that the tidal regime is contributing to the bacterial species selection in the rhizosphere. Despite the observed diversity in the bacterial community structure, the plant growth promoting (PGP) potential of cultivable rhizospheric bacteria, assessed through in vitro and in vivo tests, was equally distributed along the tidal gradient. Root colonization tests with selected strains proved that halophyte rhizospheric bacteria (i) stably colonize S. strobilacea rhizoplane and the plant shoot suggesting that they move from the root to the shoot and (ii) are capable of improving plant growth. The versatility in the root colonization, the overall PGP traits and the in vivo plant growth promotion under saline condition suggest that such beneficial activities likely take place naturally under a range of tidal regimes.

Bacterial endophytes of mangrove propagules elicit early establishment of the natural host and promote growth of cereal crops under salt stress

“…Coastal ecosystems are subjected to cyclic shifts of different environmental conditions such as nutrient availability and salinity and oxygen concentrations in the soil and sediments (Alongi, 1988;Mitra et al, 2008). The importance of plant growth promoting (PGP) bacteria in coastal ecosystems was largely reported (Gontia et al, 2011;Jha et al, 2012;Mapelli et al, 2013;Marasco et al, 2016;Mesa et al, 2015;Siddikee, 2010), as well as the influence of the tidal regime on the selection of specific bacterial assemblages in the root systems (Marasco et al, 2016;Wang et al, 2015).…”

Root bacterial endophytes confer drought resistance and enhance expression and activity of a vacuolar H+‐pumping pyrophosphatase in pepper plants

“…In arid environments, desert farming favours the selection of drought‐protecting microbial assemblages (Marasco et al ., ; TerHorst et al ., ; Soussi et al ., ) that are enriched and rearranged in the plant rhizosphere and endosphere (Mapelli et al ., ; Marasco et al ., ; ; Cherif et al ., ; Ferjani et al ., ; Santos‐Medellín et al ., ). PGP microorganisms use several mechanisms to stimulate drought tolerance in plants (Vurukonda et al ., ; Etesami and Maheshwari, ): (i) the microbial enzyme 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase contributes to control the concentration of the plant stress phytohormone ethylene, by degrading its precursor ACC (Glick, ); (ii) microorganisms contribute to modulate plant hormone homeostasis by producing auxin [i.e., indole‐3‐acetic acid (IAA)], cytokinins and giberellins.…”

Diversity of Bacterial Microbiota of Coastal Halophyte Limonium sinense and Amelioration of Salinity Stress Damage by Symbiotic Plant Growth-Promoting Actinobacterium Glutamicibacter halophytocola KLBMP 5180

“…Several studies have suggested that the habitat-adapted symbiotic microorganisms associated with plants growing in harsh environments might help these host plants tolerate abiotic stresses (22)(23)(24). Recently, halophyte-associated endophytes and rhizosphere microorganisms have been shown to increase the salt tolerance of the host plants (25)(26)(27)(28). However, few details of halophyte microbiota composition are available, and the mechanisms by which halophyte-associated microbes increase salinity tolerance in halophytes remain unclear.…”