Osmotolerant plant growth promoting bacterial inoculation enhances the anti-oxidant levels of tomato plants ender water stress conditions

Abstract

Drought stress alters productivity of crops in general and horticultural crops in particular resulting in poor quality produce and reduced yields. When plants are exposed to severe water stress, they suffer from membrane destabilization and general nutrient imbalances that alter their physiology anddefence mechanisms. The antioxidant enzyme system of plants plays an important role in the scavenging of Reactive Oxygen Species (ROS) that accumulate during stress, and is the first line of defence to counter the deleterious stress effects. In this study the effects of osmotolerant bacterial inoculation on the protein content,antioxidant enzymes viz.,catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), glutathione reductase (GR) and the proline content of tomato plants subjected to continued water stress for a period of 144 h, was determined.It was evident that across bacterial treatments, plants inoculated with osmotolerant rhizobacterial strainsrecorded elevated levels of antioxidant enzymes compared to the uninoculated plants.But the isolates showed variability in enhancing the levels of the different antioxidant enzymes studied. Under water stressed conditions plants inoculated with EnterobacterP-68,EnterobacterP-46,EnterobacterP-39 and BacillusG-4 recorded the highest activities ofperoxidase, superoxide dismutase, catalase and glutathione reductase respectively, while plants inoculated with Bacillus amyloliquefaciens P-72 recorded the highest levels of proline accumulation