Improvement of Brassica napus growth under cadmium stress by cadmium-resistant rhizobacteria

摘要: Abstract This study focuses on the characterization of four bacterial isolates from heavy metal-polluted rhizosphere in order to examine their plant growth promoting (PGP) activity. The PGP activity canola ( Brassica napus ) strains which showed cadmium resistance and multiple traits was assessed presence absence Cd 2+ . strains, Pseudomonas tolaasii ACC23, fluorescens ACC9, Alcaligenes sp. ZN4 Mycobacterium ACC14 1-aminocyclopropane-1-carboxylate deaminase (ACCD) They also synthesized ACCD enzyme vitro when 0.4 mM added medium. metal, however, reduced ACC14, while it did not affect P. ACC23 ACC9. ACC9 produced indole acetic acid (IAA) siderophores, only IAA. IAA siderophores were more actively under Cd-stress. Root elongation assays conducted B. gnotobiotic conditions demonstrated increases (from 34% up 97%) root inoculated seedlings compared control plants. Subsequently, effect inoculation with these uptake roots shoots studied pot experiments using Cd-free Cd-treated (15 μg Cd  g −1  dw) soil. Inoculation promoted plants at concentrations 0 15 μg Cd  soil. maximum observed ACC23. influence specific accumulation shoot systems, but all increased biomass consequently total accumulation. present observations that used this protect against inhibitory effects cadmium, probably due production IAA,