Agarwal et al. [45] and Horvath et al. [9] also observed that SA application

can improve plant biomass and enhance the antioxidant response FG-4592 chemical structure against osmotic stress. The same is shown in our findings when we applied SA to pepper plants as compared to control plants. During endophytic-fungal association, it was observed that the SA application to EA plants significantly increased the growth and metabolism as compared to sole SA and control plants. Furthermore, the biomass loss was much pronounced in non-inoculated and sole SA plants as compared to EA and SA+EA plants. Previously, it was shown that exogenous SA to roots of fungal-inoculated rice does not inhibit the root colonization of fungi [12]. Ludwig-Müller et al.

[13] also reported that exogenous SA did not effected the root colonization by growth promoting fungi. However, our data shows the increased endophytic-colonization in SA treated host plants. This was also conformity to the results of Liu et al. [19], who indicated that exogenous SA application to fungal (Glomus mosseae) inoculated Avena nuda plants has increased the abiotic stress tolerance and had beneficial impacts on fungal colonization. The SA application Elafibranor supplier to endophyte-inoculated plants not only increased endophytes abundance but also increased the host plant biomass, antioxidants and endogenous SA contents. It was shown that endogenous SA increased in endophyte-inoculated plants treated with SA as compared to sole SA and control plants under osmotic stress conditions. Increased endogenous SA and antioxidant activities play an important role in abiotic and biotic defense signaling [47, 48]. Under abiotic stress, high endogenous SA may

mitigate the negative effects of ROS accumulation. Such functions can counteract the adverse effects of stress under mutualistic relationship as SA initiates induced systemic resistance [51]. Enhanced SA levels are especially important to reduce the susceptibility of plants to biotic and abiotic stresses [51]. We assume Atorvastatin that the ISR stimulated through endophyte association activated the SA responses during osmotic stress. Mutualistic relationship initiates ISR and improves plant performance against biotic and abiotic stresses [43]. However, this concept is still overlooked in endophyte-induced ISR. Although Penicillium spp. have been known as potential inducers of ISR in various plants [11], our scientific understanding of the molecular mechanisms by which Penicillium sp. influence the outcome of plant abiotic stress tolerance is still marginal. Conclusion Fungal endophyte, P. resedanum not only improves plant growth but also extend greater benefits to the host-plants to mitigate the negative effects of gradual osmotic stress. Exogenous SA application to pepper plant improved the stress tolerance of the plants while in combination with endophyte-inoculation it further regulated the stress impacts.