title: Characterization of endophytic Rahnella sp. JN6 from Polygonum pubescens and its potential in promoting growth and Cd, Pb, Zn uptake by Brassica napus.
abstract: Microbe-assisted phytoremediation has been considered as a promising measure for the remediation of heavy metal-polluted soils. In this study, a metal-tolerance and plant growth-promoting endophytic bacterium JN6 was firstly isolated from roots of Mn-hyperaccumulator Polygonum pubescens grown in metal-contaminated soil and identified as Rahnella sp. based on 16S rDNA gene sequence analysis. Strain JN6 showed very high Cd, Pb and Zn tolerance and effectively solubilized CdCO(3), PbCO(3) and Zn(3)(PO(4))(2) in culture solution. The isolate produced plant growth-promoting substances such as indole-3-acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and also solubilized inorganic phosphate. Based upon its ability in metal tolerance and solubilization, the isolate JN6 was further studied for its effects on the growth and accumulation of Cd, Pb and Zn in Brassica napus (rape) by pot experiments. Rape plants inoculated with the isolate JN6 had significantly higher dry weights, concentrations and uptake of Cd, Pb and Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg(-1)), Pb (200 mg kg(-1)) or Zn (200 mg kg(-1)). The isolate also showed a high level of colonization in tissue interior of rapes. The present results demonstrated that Rahnella sp. JN6 is a valuable microorganism, which can cost-effectively improve the efficiency of phytoremediation in soils contaminated by Cd, Pb and Zn.
authors.affiliation: Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, College of Life Sciences, South China Normal University, Guangzhou 510631, PR China.
authors.forename: Huaidong
authors.initials: H
authors.lastname: He
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Ye
authors.forename: Danjing
authors.initials: D
authors.lastname: Yang
authors.forename: Junlan
authors.initials: J
authors.lastname: Yan
authors.forename: Li
authors.initials: L
authors.lastname: Xiao
authors.forename: Ting
authors.initials: T
authors.lastname: Zhong
authors.forename: Ming
authors.initials: M
authors.lastname: Yuan
authors.forename: Xinde
authors.initials: X
authors.lastname: Cai
authors.forename: Zhanqiang
authors.initials: Z
authors.lastname: Fang
authors.forename: Yuanxiao
authors.initials: Y
authors.lastname: Jing
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D001937:Brassica / Q000254:growth & development / Q000378:metabolism*; D002104:Cadmium / Q000032:analysis / Q000378:metabolism; D007854:Lead / Q000032:analysis / Q000378:metabolism; D019216:Metals, Heavy / Q000032:analysis / Q000378:metabolism*; D008969:Molecular Sequence Data; D028502:Polygonum / Q000382:microbiology*; D020638:Rahnella / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D015032:Zinc / Q000032:analysis / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D015032:Zinc