Interaction of ACC deaminase and antioxidant enzymes to induce drought tolerance in Enterobacter cloacae 2WC2 inoculated maize genotypes

摘要

Beneficial endophytic bacteria are well known for plant growth enhancement, induced plant defense responses and antioxidant activities that confer resistance against various biotic and abiotic stresses by utilization of 1-aminocyclopropane1-carboxylate deaminase activity. A plant growth promoting endophytic (PGPE) bacteria Enterobacter cloacae 2WC2 strain was investigated for its role in drought stress amelioration and plant growth promotion via ACC deaminase activity and enhanced levels of antioxidant enzymes in stressed plants. Invitro screening revealed drought tolerance of E. cloacae at various stress levels (10-40 % PEG 6000) and showed resistance against 15 different antibiotics. Furthermore, its positive results for indole acetic acid (IAA), ammonia production, catalase, and phosphate solubilization revealed its growth promoting attributes. Exopolysaccharide production and ACC deaminase activity (0.95 μM/mg protein/h exposed its potential as competing candidate in drought stressed conditions. In a pot experiment, two maize genotypes TP 30 and TPSSWD either inoculated with or without E. cloacae were grown to investigate its effectiveness under drought stress. Experiment was conducted in a completely randomized design under factorial arrangement with three water regimes 100% FC (control), 75% FC (mild stress) and 40% FC (severe stress). Drought stress significantly reduce maize growth, however inoculation with E. cloacae 2WC2 elevated the morphological variables, relative water content and antioxidant activity, at all stress levels. Results showed that maize variety TP 30 was found to be more drought tolerant as compared to variety TPSSWD. Current findings suggest inoculation of plants by ACC deaminase producing endophytic bacteria, could be harnessed as an effective approach for sustainable crop production in drought stressed conditions.