INDUCING PLANT RESISTANCE AGAINST SALINITY USING SOME RHIZOBACTERIA | ||
| Egyptian Journal of Desert Research | ||
| Article 11, Volume 67, Issue 1 - Serial Number 67, June 2017, Pages 187-208 PDF (1.42 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejdr.2017.6498 | ||
| Author | ||
| Amal M. Omer* | ||
| Department of Soil Fertility and Microbiology, Desert Research Center, El-Matareya, Cairo, Egypt | ||
| Abstract | ||
| Activity of 1-aminocyclopropane-1-carboxylate (ACC)-deaminase of rhizobacteria isolated from salt-stressed rhizospheres were screened based on their utilization of ACC as sole nitrogen source. Twenty percentage of the isolates achieved remarkable differences in the activities of ACC-deaminase ranged from 180 to 1398 nm α-ketobutyrate mg-1 h-1. Phylogenetic analysis of 16S rRNA sequence of two strains with the highest level of ACC-deaminase activity revealed the first isolate was identified as Alcaligenes faecalis subsp. parafaecalis strain G and the second as Alcaligenes faecalis strain NBRC 13111. The influence of ACC-deaminase rhizobacteria on the ACC-induced classical triple response in etiolated wheat seedlings were studied. Results revealed that exogenous application of 3 mmol L-1 ACC creating classical triple response in seedlings under salt stress (10% NaCl). Inoculation with two ACC-deaminase rhizobacteria decreased the ACC-imposed classical triple response in etiolated seedlings, as significant increases in seedling length, root elongation and reduction in stem diameter over uninoculated ACC-stressed control were recorded. Studying the effect of salinity ranged from 0 to 10% NaCl on the growth and ACC-deaminase activitiy of the two bacterial strains revealed that gradual reduction in both growth and enzyme activity were demonstrated with increasing salinity. Both strains could tolerate the salinity up to 7% NaCl, A. faecalis strain G showed the highest ACC-deaminase activity at 1% concentration of NaCl, while A. faecalis strain NBRC recorded the highest enzyme activity at 3% NaCl. Two field experiments were conducted during 2014/15 and 2015/20116 at Ras Sudr Experimental Station to evaluate the effect of ACC-deaminase bacteria on the growth and productivity of wheat under salt stress condition. For all yield traits and chemical constituents of wheat grains, significant increase were recorded under ACC-deaminase bacterial inoculation comparing to control in both seasons of planting. The highest increase in the total microbial counts, CO2 evolution and dehydrogenase activity of the rhizosphere regions were indicated in plants inoculated with bacterial strains regardless the type of bacteria used. The results indicated that inoculation with ACC-deaminase rhizobacteria can serve as promising economical alternative alleviated plant stress caused by salinity. | ||
| Keywords | ||
| Alcaligenes faecalis; ACC-deaminase activity; salinity; Wheat | ||
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