molecular identification of the iranian native acc deaminase producing rhizobacteria using 16s rdna sequence analysis

one of the important mechanisms utilized by the plant growth promoting rhizobacteria (pgpr) is lowering of ethylene levels by the 1-aminocyclopropane-1-carboxylic acid (acc) deaminase enzyme. the mechanism facilitates plant growth and development in the stress conditions. pgpr containing acc deaminase can promote plant growth under stress and overcome the harmful effects. the study aimed to screen and identify the acc deaminase producing rhizobacteria isolated from the soils of different regions in iran. fifty-seven isolated strains of rhizobacteria were cultured in the m9 medium with two different nitrogen sources (contains acc and nh4cl), in two replications. the control treatment was nitrogen free m9 medium. in this study, canola seeds, sari gol cultivar, were also inoculated with the acc deaminase producing rhizobacteria for evaluating their effects on the shoot and root elongation during 5 days germination based on a completely randomized design with three replications. finally, the best acc deaminase producing rhizobacteria was identified by the sequencing of 16s rdna gene. results showed that just 8 isolated rhizobacteria strains (out of 57) produced acc deaminase, of which cma3 and wah3 had the greatest effects on the stem and root length, respectively. cma3 and wah3 were identified as klebsiella and pseudomonas genus, respectively. the identified strains can be useful for the crop growth in stress conditions.