Biotic priming with Pseudomonas fluorescens induce drought stress tolerance in Abelmoschus esculentus (L.) Moench (Okra)

Drought is a major abiotic stress which negatively affects plant growth and yield. The decrease in rainfall and ensuing drought affect crop production to a larger extent. The present investigation was aimed to evaluate the drought stress mitigation potential of Abelmoschus esculentus (L.) Moench (okra) plants primed with Pseudomonas fluorescens (PF). Okra seeds were primed with 10(-7) CFU of PF, germinated and the plants were exposed to drought stress for 7days, and the recovery potential was assessed after re-watering the plants. Physiological and biochemical parameters were evaluated during stress and recovery. PF treated plants mitigated the effect of drought stress by increasing relative water content (RWC), accumulated metabolites such as sugar, free amino acids and enhanced the activity of non enzymatic antioxidants; phenolics, ascorbate (AsA) and glutathione (GSH) and reactive oxygen species scavenging enzyme like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaicol peroxidase (GPX). Drought stress related membrane damage and protein denaturation were also alleviated by PF treatment. During re-watering, PF treated plants regained RWC, total sugar, total amino acid, protein, AsA, GSH, phenolics, SOD, CAT, APX and GPX to appreciable levels. Thus, this study suggests that PF can be used as an agent to effectively mitigate drought stress in okra plants.