ROS are removed from the cell directly (catalase and peroxidase) or indirectly (redox molecules like glutathione). The present Silmitasertib concentration findings showed higher levels of glutathione and total polyphenol and lower levels of lipid peroxidation and superoxide anion formation in the pepper plants associated with P. resedanum. The effects were more significant in SA+EA treated plants. It indicated that membrane injury was lower in endophyte-associated plants (EA and SA+EA) as the plants had lesser electrolytic leakage and lipid peroxidation (MDA content). Since membrane bounded lipid hydroperoxides are difficult to measure due to their instability, therefore we measured the degree of lipid

peroxidation to quantify secondary breakdown products like MDA. Higher ROS, on the other hand, autocatalyze peroxidation of lipid membrane and affect membrane 3 MA semi-permeability under high drought stress. Activation of antioxidant scavengers can enhance membrane stability against ROS attack while MDA content can be used to assess the stress injury of plants [43]. In stress related antioxidant enzymes, higher catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO) activities were observed in endophyte-infected plants as see more compared to non-infected control and sole SA-treated plants. CAT, POD and PPO have also been known to articulate the ROS induced oxidative burst. Increased

catalase activity is associated with increased root length and enhanced seedling growth as shown by Harman [40]. Similarly, peroxidase and is polyphenol oxidase protects cells against the destructive influence of H2O2 by catalyzing its decomposition through the oxidation of phenolic osmolytes [44]. Previously, researchers have identified the crop growth regulation under stress conditions through activation of CAT, POD and PPO [20,

31, 45]. Similarly, the importance of endophyte colonization in terms of antioxidant Tyrosine-protein kinase BLK activity and ROS production has been shown significance and often positive for the host-plant fitness [46], however this could be further verified by further experiments in case of P. resedanum. Co-synergism of SA with endophyte under osmotic stress The SA application to the pepper plants had a growth promoting effect as compared to control plants. The SA also helped the plants to counteract the negative effects of osmotic stress. The effect of SA and EA on pepper shoot growth, chlorophyll contents was almost similar as compared to SA+EA treatments but this effect was significantly higher than control plants. Exogenous SA is known for its role in abiotic stress mitigation. In recent past, SA application has evidenced improved plant growth against abiotic stress [47–49]. Previous studies have shown that SA application to maize plant helped in alleviating the negative effects on the plants under drought stress [49].