Abstract
In the present study, plant growth promoting rhizobacterial (PGPR) strains Pseudomonas fluorescence strain P2, Pseudomonas jessenii R62, Pseudomonas synxantha R81, Bacillus cereus BSB 38 (14B), Arthrobacter nitroguajacolicus strainYB3 and strain YB5 were tested for their role in enhancing plant growth and induction of stress related enzymes in Sahbhagi (drought tolerance) and IR-64 (drought sensitive) cultivars of rice (Oryza sativa L.) under different level of drought stress. PGPRs, P. jessenii, R62, P. synxantha, R81 were used as one consortium similarly A. nitroguajacolicus strainYB3 and strain YB5 were used as other consortia. Most of the PGPR inoculated plants showed enhanced growth as compared to uninoculated plants under all the level of drought stress. Quantitative analyses of antioxidant enzymes indicated that majority of the PGPRs inoculated plants in both varieties showed higher proline content, higher activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and lower level of hydrogen peroxide (H2O2), malondialdehyde (MDA) in leaves at all the level of drought stress. The study suggests that PGPRs alleviates oxidative damage in rice plants grown under drought by improving plant growth and activating antioxidant defense systems, thereby improving stability of membranes in plant cells. This study provides evidence for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions. Key words: Plant growth promoting rhizobacterial (PGPR), plant growth promotion, drought stress, antioxidant, rice.
Highlights
Rice (Oryza sativa L.) is the staple food consumed by more than half of the world population and fulfills 23% of their caloric demands (Khush, 2003)
(Mader et al, 2011; Roesti et al, 2006), two strains of Arthrobacter nitroguajacolicus, strainYB3 and YB5 (Gusain et al, 2015), Bacillus cereus BSB 38 (14B), and Pseudomonas fluorescence strain P2 were kindly provided by Rhizosphere biology lab of the Department of Biological Sciences of G
The plants were harvested at 0 days, 8 days and 10 days of drought and all these stages the soil moisture content of pot were measured as 640 ± 17.83, 62 ± 03.09 and 37
Summary
Rice (Oryza sativa L.) is the staple food consumed by more than half of the world population and fulfills 23% of their caloric demands (Khush, 2003). International License half of the rice areas in the world do not maintained flooded condition and reduced yield, to some extent, as a result of drought (Bernier et al, 2008). Under varieties of environmental stress including drought, plants showed increased level of reactive oxygen species (ROS) (Sgherri et al, 1996), which includes superoxide ._. Enhanced membrane lipid peroxide-tion takes place in both cellular and organelle membranes when ROS reaches above threshold level, which, in turn affect normal cellular functioning and act as an indicator of ROS mediated damage to cell membranes under stressful conditions (Mishra et al, 2011) and can be measured by malondialdehyde (MDA) content, one of the final products of peroxide-tion of unsaturated fatty acids in phospholipids of membrane (Halliwell and Gutteridge, 1989).
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