Properties of Astragalus sp. microsymbionts and their putative role in plant growth promotion

Abstract

The plant growth-promoting rhizobacteria have developed many different (indirect and direct) mechanisms that have a positive effect on plant growth and development. Strains isolated from Astragaluscicer and Astragalusglycyphyllos root nodules were investigated for their plant growth-promoting properties such as production of indole-3-acetic acid (IAA) and siderophores, phosphate solubilization, ACC deaminase activity, and tolerance to heavy metals. IAA production and P-solubilization were frequent features in the analysed strains, while siderophores were not produced by any of them. In this work, we investigated the presence of the acdS genes and ACC deaminase activities in Astragalauscicer and A. glycyphyllos microsymbionts, classified within the genus Mesorhizobium. The results demonstrated that the acdS gene is widespread in the genome of Astragalus sp. microsymbionts; however, none of the tested strains showed ACC deaminase activity. The acdS gene sequence similarity of the analysed strains to each other was in the range from 84 to 99 %. On the phylogram of acdS gene sequences of milkvetch, the symbionts clustered tightly with the genus Mesorhizobium bacteria.Electronic supplementary materialThe online version of this article (doi:10.1007/s00203-016-1243-3) contains supplementary material, which is available to authorized users.

Diversity and plant growth promoting properties of rhizobia isolated from root nodules of Ononis arvensis

“…Production of indole in tryptophan broth was studied (Gnat et al 2014 ). IAA production was examined with the method described by Wdowiak-Wrobel and Malek ( 2016 ). The phosphate solubilizing ability of the studied bacteria was tested on Pikovskaya’s agar (Gupta et al 2012 ) containing tricalcium phosphate (TCP) as an insoluble phosphate source.…”

Genetic and physiological diversity of white Spanish broom (Chamaecytisus albus) endophytes

“…The production of IAA and indole was examined using the TMRT medium (Wdowiak-Wróbel & Małek, 2016). 5-ml aliquots of liquid TMRT were inoculated with 10 μl of bacterial cells of the studied isolates suspended in saline (OD 550 =0.2) and incubated for 5 days at 28°C with shaking (170 rpm).…”

“…5-ml aliquots of liquid TMRT were inoculated with 10 μl of bacterial cells of the studied isolates suspended in saline (OD 550 =0.2) and incubated for 5 days at 28°C with shaking (170 rpm). After that, the bacterial cultures were divided: one half was used for detection of IAA production with 0.01 M FeCl 3 in 35% HClO 4 (Wdowiak-Wróbel & Małek, 2016), and the other one was used for detection of indole production with the Kovacs reagent (MacWilliams, 2009). The experiment was performed in triplicate.…”

Bacteria-Inducing Legume Nodules Involved in the Improvement of Plant Growth, Health and Nutrition

“…Phosphate solubilization is the second plant growth-promoting mechanism involved in nutrient mobilization presented by rhizobia (Rodríguez and Fraga, 1999;. Within them, the most active phosphate solubilizers in vitro are the species included into the genus Mesorhizobium (Peix et al 2001;Rivas et al 2006;Verma et al 2013;Imen et al 2015;Wdowiak-Wróbel and Małek 2016;Brígido et al 2017), although this mechanism is also presented by strains of Rhizobium (Chabot et al 1996;Antoun et al 1998;Alikhani et al 2007;Abril et al 2007;Sridevi et al 2007;Flores-Félix et al 2013;Dahale et al 2016;Othman and Tamimi 2016;Jiménez-Gómez et al 2018), Ensifer (formerly Sinorhizobium) (Ormeño et al 2007;Villar-Igea et al 2007) and Bradyrhizobium (Boiero et al 2007).…”