isolation, identification and effectiveness of acc deaminase producing rhizobacteria on the alleviation of salinity stress effects on canola growth

abstract the aim of the present research was to isolate plant growth promoting rhizobacteria producing acc deaminase which was able to alleviate negative effects of salinity on plant growth. 21 composite soil samples and canola roots were collected from the saline and relatively saline soils of qom and qazvin provinces. 105 strains were selected from the soil rhizosphere of canola. according to the growing abilities of the strains in the minimum media of df having acc, as the only source of nitrogen, it was determined that 14 strains had the ability to produce acc deaminase. identification of strain was carried out according to bergey’s manual criteria. results indicated that all the strains belonged to the group of fluorescent pseudomonads. according to the tests, related to strain determination, 14 strains were identified as p. fluorescent. measuring acc deaminase activity showed that the activity of this enzyme in the isolated strains differed from 1.43 to 8.17 μmol α-ketobutyrate/mg/hr. also the isolates produced iaa in tsb medium between 0.8 – 2.17 μmol/ml. in the present study, effect of selected strains on reducing negative effects of salinity on canola seedlings growth was evaluated under greenhouse conditions. under salinity stress, all acc deaminase producing strains were able to increased canola growth parameters containing shoot fresh and dry weight, shoot and root length. among tested strains, p12 was the most effective. there was a high correlation between root length and dry matter, and the activity of acc deaminase producing bacteria. also with increase salinity from 6 to 8 ds/m, shoot fresh weight and stem length were significantly decreased. keyword: acc deaminas, pseudomonas, canola, salinity