title: 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 Astragalus cicer and Astragalus glycyphyllos 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 Astragalaus cicer 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.
authors.affiliation: Department of Genetics and Microbiology, Maria Curie Skłodowska University, Akademicka 19 St., 20-033, Lublin, Poland. s.wdowiak@poczta.umcs.lublin.pl.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Wdowiak-Wróbel
authors.affiliation: Department of Genetics and Microbiology, Maria Curie Skłodowska University, Akademicka 19 St., 20-033, Lublin, Poland.
authors.forename: Wanda
authors.initials: W
authors.lastname: Małek
mesh_terms: D027883:Astragalus Plant / Q000382:microbiology*; D019755:Carbon-Carbon Lyases / Q000235:genetics / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D059128:Mesorhizobium / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D019216:Metals, Heavy / Q000378:metabolism; D063245:Plant Development; D018517:Plant Roots / Q000382:microbiology; D012231:Rhizobium / Q000235:genetics / Q000302:isolation & purification; D017262:Siderophores / Q000378:metabolism; D013559:Symbiosis
chemical_list: D005030:Ethylenes; D007210:Indoleacetic Acids; D019216:Metals, Heavy; D017262:Siderophores; C030737:indoleacetic acid; C036216:ethylene; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases
keywords: Astragalus sp. microsymbionts; PGPR; acdS gene