Pedosphere 27(3): 511--526, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Plant growth-promoting traits in rhizobacteria of heavy metal-resistant plants and their effects on Brassica nigra seed germination
Brenda ROMÁN-PONCE, Diana Miryel REZA-VÁZQUEZ, Sonia GUTIÉRREZ-PAREDES, María de Jesús DE HARO-CRUZ, Jessica MALDONADO-HERNÁNDEZ, Yanely BAHENA-OSORIO, Paulina ESTRADA-DE LOS SANTOS, En Tao WANG,María Soledad VÁSQUEZ-MURRIETA
Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Prolongación Carpio y Plan de Ayala s/n, Col.Santo Tomás, Del. Miguel Hidalgo Ciudad de México, C.P. 11340 (Mexico)
ABSTRACT
      Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up pollutants from the soil, water, and air. In order to select the plant growth-promoting rhizobacteria (PGPR) for phytoremediation of heavy metal contamination, 60 bacterial strains were isolated from the rhizosphere of two endemic plants, Prosopis laevigata and Spharealcea angustifolia, in a heavy metal-contaminated zone in Mexico.These rhizobacterial strains were characterized for the growth at different pH and salinity, extracellular enzyme production, solubilization of phosphate, heavy metal resistance, and plant growth-promoting (PGP) traits, including production of siderophores and indol-3-acetic acid (IAA).Overall, the obtained rhizobacteria presented multiple PGP traits. These rhizobacteria were also resistant to high levels of heavy metals (including As as a metalloid) (up to 480 mmol L-1 As(V), 24 mmol L-1 Pb(II), 21 mmol L-1 Cu(II), and 4.5 mmol L-1 Zn(II)).Seven rhizobacterial strains with the best PGP traits were identified as members of Alcaligenes, Bacillus, Curtobacterium, and Microbacterium, and were selected for further bioassay. The inoculation of Brassica nigra seeds with Microbacterium sp.CE3R2, Microbacterium sp.NE1R5, Curtobacterium sp.NM1R1, and Microbacterium sp.NM3E9 facilitated the root development; they significantly improved the B. nigra seed germination and root growth in the presence of heavy metals such as 2.2 mmol L-1 Zn(II).The rhizobacterial strains isolated in the present study had the potential to be used as efficient bioinoculants in phytoremediation of soils contaminated with multiple heavy metals.
Key Words:  bioinoculants, endemic plants, mine tailings, pH, phytoremediation, salinity
Citation: Brenda ROMÁN-PONCE, Diana Miryel REZA-VÁZQUEZ, Sonia GUTIÉRREZ-PAREDES, De, H. C., Jessica, M. H., Yanely, B. O., Paulina, E. D., Tao, W. and María Soledad VÁSQUEZ-MURRIETA. 2017. Plant growth-promoting traits in rhizobacteria of heavy metal-resistant plants and their effects on Brassica nigra seed germination. Pedosphere. 27(3): 511-526.
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