Endophytic aspergillus oryzae reprograms Abelmoschus esculentus L. to higher growth under salt stress via regulation of physiochemical attributes and antioxidant system

Salt stress is one of the leading growth-retarding factors among all the abiotic stresses that affect 30% of worldwide-irrigated land. Researchers are employing different strategies and approaches to manage this problem. However, some of the strategies are costly while others are time consuming. On the other hand, the use of endophytes is pragmatic, cheap and eco-friendly. This work investigated the potential role of endophytic Aspergillus oryzae CM1 in the mitigation of salinity-induced stress in Abelmoschus esculentus. NaCl stress altered the morphological and physio-biochemical attributes as well as phytohormones in okra plants. The inoculation of endophytic A. oryzae CM1 significantly increased growth attribute (shoot/root length), biomass (fresh/dry weight), chlorophyll (a, b) and carotenoids contents, IAA, total soluble sugar and relative water content (RWC) in okra. The malondialdehyde (MDA) and proline content in the okra seedlings increased by 91.21% and 38.83%, respectively. Increase in phenolic and flavonoid contents were witnessed in NaCl stressed okra plants inoculated with isolate CM1. NaCl stress (100 mM) decreased IAA content in leaves (32.57%), stem (22.01%) and roots (19.65%) of the control okra seedlings. However, an increase in IAA contents in leaves (143.04%), stem (115.32%), and roots (60.28%) were observed in okra plants inoculated with isolate CM1. By investigating the chemical profile of A. oryzae CM1 crude extract, we found sinapiic acid, 3,4-dimethyl-caffeic-acid, feruloylquinic-acid, coniferylaldehyde hexoside, cycloolivil, glucaric-acid, moracenin, kuwanon, sinapyl aldehyde, sophocarpine, propoxyphene and myricetin. Thus, NaCl stress causes an adverse effect on okra, however, the colonization of endophytic A. oryzae improves NaCl tolerance by ameliorating the physio-biochemical attributes and phytohormones production in host plant species.