Bacterial endophytes from halophyte black saxaul (Haloxylon aphyllum Minkw.) and their plant growth-promoting properties

Abstract

The purpose of the present research was to study the diversity of bacterial endophytes inhabiting the halophytic plant black saxaul (Haloxylon aphyllum Minkw.). A total of 20 bacterial isolates were isolated from tissues of black saxaul and identified based on their 16S rRNA genes analysis and comparison with the closest relatives registered in GenBank nucleotide data bank from the National Centre for Biotechnology Information. The endophytes were checked for plant growth-promoting activity toward cucumber plants and the strains Bacillus amyloliquefaciens HAPH2, Priestia endophytica HAPH5, Bacillus subtilis HAPH7, Bacillus toyonensis HAPH8, Halomonas sulfidaeris HAPH11, Isoptericola halotolerans HAPH12, Planomicrobium soli HAPH15, and Pseudomonas kilonensis HAPH16 demonstrated high plant growth-promoting activity of cucumber in four soil salinity levels (0, 25, 50, and 100 mM) after seeds' inoculation. These bacterial endophytes were able to fix nitrogen, solubilize phosphates, and produce indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, and siderophores which are considered as the main plant growth-promoting traits. After field experiments, the best plant growth-promoters can be used as bioinoculants for plants' growth improvement in salinity conditions.

Salt-tolerant PGPR strain Priestia endophytica SK1 promotes fenugreek growth under salt stress by inducing nitrogen assimilation and secondary metabolites

“…Inoculation of fenugreek plants with P. endophytica SK1 enhanced P content in both control and salt-stressed plants. Similar observations of increase in P uptake in plants through co-inoculation with phosphate-solubilizing bacteria has been reported earlier (Egamberdieva et al, 2022;Kumar et al, 2020;Shurigin et al, 2022). P. endophytica SK1, in the present study, was able to solubilize phosphate enabling more P uptake in fenugreek plant under salt stress.…”

“…In another study, Priestia endophytica was isolated from halophytic plant tissue black saxaul ( Haloxylon aphyllum Minkw.) and possessed PGP capabilities, suggesting the role of this bacterium in the host plant survival under salt stress conditions (Shurigin et al, 2022). The isolation of SK1 from the fenugreek rhizosphere suggests its biological significance in salt stress tolerance and plant growth promotion of the host plant.…”

Isolation and plant growth promoting properties of bacterial endophytes from wild plant (Wedelia urticifolia) of south Gujarat region

“…Semi-solid Rennie media [13][14][15] was used to screen the Nitrogen fixing capacity of the isolated entophytic strains. After autoclaving, filter-sterilized biotin and Para amino benzoic acid were added to final concentrations of 5 and 10 μg per liter.…”

“…The qualitative phosphate solubilization test was carried out using spot inoculation technique on agar plate containing insoluble tricalcium phosphate (TCP) and incubated at 30 °C for 4 to 5 days and observed the zone of solubilization (15,16). The phosphate solubilization index (PSI) was calculated using the following formula.…”

“…Quantitative estimation of P solubilize by the selected isolates was conducted by following [15,17] . Isolates selected were cultivated in 100 mL Pikovskaya liquid medium and incubated in shaking incubator for 7 days at 37 °C.…”