title: Survey of Plant Growth-Promoting Mechanisms in Native Portuguese Chickpea Mesorhizobium Isolates.
abstract: Rhizobia may possess other plant growth-promoting mechanisms besides nitrogen fixation. These mechanisms and the tolerance to different environmental factors, such as metals, may contribute to the use of rhizobia inocula to establish a successful legume-rhizobia symbiosis. Our goal was to characterize a collection of native Portuguese chickpea Mesorhizobium isolates in terms of plant growth-promoting (PGP) traits and tolerance to different metals as well as to investigate whether these characteristics are related to the biogeography of the isolates. The occurrence of six PGP mechanisms and tolerance to five metals were evaluated in 61 chickpea Mesorhizobium isolates previously obtained from distinct provinces in Portugal and assigned to different species clusters. Chickpea microsymbionts show high diversity in terms of PGP traits as well as in their ability to tolerate different metals. All isolates synthesized indoleacetic acid, 50 isolates produced siderophores, 19 isolates solubilized phosphate, 12 isolates displayed acid phosphatase activity, and 22 exhibited cytokinin activity. Most isolates tolerated Zn or Pb but not Ni, Co, or Cu. Several associations between specific PGP mechanisms and the province of origin and species clusters of the isolates were found. Our data suggests that the isolate's tolerance to metals and ability to solubilize inorganic phosphate and to produce IAA may be responsible for the persistence and distribution of the native Portuguese chickpea Mesorhizobium species. Furthermore, this study revealed several chickpea microsymbionts with potential as PGP rhizobacteria as well as for utilization in phytoremediation strategies.
authors.affiliation: ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas (Laboratório de Microbiologia do Solo), Universidade de Évora, Núcleo da Mitra, Ap. 94, 7002-554, Évora, Portugal.|IIFA-Instituto de Investigação e Formação Avançada, Universidade de Évora, Ap. 94, 7002-554, Évora, Portugal.
authors.forename: Clarisse
authors.initials: C
authors.lastname: Brígido
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Glick
authors.affiliation: ICAAM-Instituto de Ciências Agrárias e Ambientais Mediterrânicas (Laboratório de Microbiologia do Solo), Universidade de Évora, Núcleo da Mitra, Ap. 94, 7002-554, Évora, Portugal. ismo@uevora.pt.
authors.forename: Solange
authors.identifier: 0000-0002-4167-5253
authors.initials: S
authors.lastname: Oliveira
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D001673:Biodegradation, Environmental; D044822:Biodiversity; D029863:Cicer / Q000254:growth & development* / Q000382:microbiology*; D003583:Cytokinins / Q000096:biosynthesis; D004269:DNA, Bacterial / Q000235:genetics; D005843:Geography; D007210:Indoleacetic Acids / Q000378:metabolism; D059128:Mesorhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism; D009586:Nitrogen Fixation; D010710:Phosphates / Q000737:chemistry; D010802:Phylogeny; D063245:Plant Development; D011174:Portugal; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012231:Rhizobium; D017422:Sequence Analysis, DNA; D017262:Siderophores / Q000096:biosynthesis; D012988:Soil Microbiology; D013559:Symbiosis; D014364:Tryptophan / Q000378:metabolism
chemical_list: D003583:Cytokinins; D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D019216:Metals, Heavy; D010710:Phosphates; D012336:RNA, Ribosomal, 16S; D017262:Siderophores; C030737:indoleacetic acid; D014364:Tryptophan; D000135:Acid Phosphatase
keywords: Chickpea; Heavy metals; Indoleacetic acid; Mesorhizobium; Phosphate solubilization; Plant growth-promoting mechanisms; Siderophores; Tolerance