Climate change is a major cause of the world's food security problems, and soil salinity is a severe hazard for a variety of crops. The exploitation of endophytic fungi that are known to have a positive association with plant roots is preferred for improving plant growth, yield, and overall performance under salt stress. The current study thus rationalized to address how salt stress affected the growth, biochemical properties, antioxidant capacity, endogenous indole-3-acetic acid (IAA), and the ionic status of maize associated with endophytic fungus (Stemphylium lycopersici). According to the findings, salt stress reduced chlorophyll a and b, total chlorophyll, total protein, sugars, lipids, and endogenous IAA levels. Enhanced values of chlorophyll a/b ratio, carotenoids, secondary metabolites (phenol, flavonoids, and tannins), antioxidant enzyme activity (catalase, ascorbate peroxidase), proline, and lipid peroxidation were noticed in maize plants under salt stress. Increased ionic content of Na+, Cl−, Na+/K+, and Na+/Ca2+ ratio, as well as decreased Ca2+, K+, Mg2+, N, and P contents, were also found in salt-stressed maize plants. In comparison to the non-saline medium, endophytic association promoted the antioxidant enzyme activities (798.7 U/g protein; catalase activity, 106 U/g protein; ascorbate peroxidase activity), IAA content (3.47 mg/g FW), and phenolics and flavonoids (88 and 1.68 μg/g FW, respectively), and decreased MDA content (0.016 nmol/g FW), Na+ ion content (18 mg/g dry weight), Cl− ion (16.6 mg/g dry weight), and Na+/K+ (0.78) and Na+/Ca2+ (1.79) ratios, in maize plants under salt stress, whereas Ca2+, K+, Mg2+, N, and P contents were increased in maize plants associated with S. lycopersici under salt stress. Current research exposed the role of S. lycopersici as an effective natural salt stress reducer and maize growth promoter; hence, it can be used as a biofertilizer to ameliorate salt stress tolerance in crops along with better growth performance in saline regions.

The present investigation envisaged revealing the role of exogenous application of ascorbic acid in increasing resistance against NaCl stress. Shoot apices from 60-d-old, in vitro-grown plants of two commercially important cultivars of Solanum tuberosum L., cvs. Desiree and Cardinal, were inoculated on Murashige and Skoog (MS) medium supplemented with 0.5 mM ascorbic acid for 72 h as a pretreatment. Pretreated and non-pretreated shoot apices were transferred to MS medium containing different concentrations of NaCl (0-140 mM; eight treatments). Results were recorded for morphological (shoot length, shoot number, root length, root number, and number of nodes) and biochemical features (protein, peroxidase, catalase, and superoxide dismutase activities) after 60 d of salt treatment. Similarly, 60-d-old, well-proliferated callus cultures were also pretreated with ascorbic acid for 24 h and transferred to an optimized callus proliferation medium containing different concentrations of salt. Results were recorded after 60 d of salt treatment for percentage relative fresh weight growth and biochemical parameters. Salinity severely inhibited all the growth parameters in both the cultivars. Pretreatment with ascorbic acid to both salttreated plants and callus cultures showed significant differences with respect to almost all of the growth and biochemical parameters studied. Protein content as well as catalase and superoxide dismutase activities increased significantly in both the cultivars, although peroxidase activity showed a decreasing trend in ascorbic acidpretreated plants as well as callus cultures.

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IntroductionDrought has become more prevalent due to dramatic climate change worldwide. Consequently, the most compatible fungal communities collaborate to boost plant development and ecophysiological responses under environmental constraints. However, little is known about the specific interactions between non-host plants and endophytic fungal symbionts that produce growth-promoting and stress-alleviating hormones during water deficits.MethodsThe current research was rationalized and aimed at exploring the influence of the newly isolated, drought-resistant, ACC deaminase enzyme-producing endophytic fungi Trichoderma gamsii (TP), Fusarium proliferatum (TR), and its consortium (TP+TR) from a xerophytic plant Carthamus oxycantha L. on Moringa oleifera L. grown under water deficit induced by PEG-8000 (8% osmoticum solution).ResultsThe current findings revealed that the co-inoculation promoted a significant enhancement in growth traits such as dry weight (217%), fresh weight (123%), root length (65%), shoot length (53%), carotenoids (87%), and chlorophyll content (76%) in comparison to control plants under water deficit. Total soluble sugars (0.56%), proteins (132%), lipids (43%), flavonoids (52%), phenols (34%), proline (55%), GA3 (86%), IAA (35%), AsA (170%), SA (87%), were also induced, while H2O2 (-45%), ABA (-60%) and ACC level (-77%) was decreased by co-inoculation of TP and TR in M. oleifera plants, compared with the non-inoculated plants under water deficit. The co-inoculum (TP+TR) also induced the antioxidant potential and enzyme activities POX (325%), CAT activity (166%), and AsA (21%), along with a lesser decrease (-2%) in water potential in M. oleifera plants with co-inoculation under water deficit compared with non-inoculated control. The molecular analysis for gene expression unraveled the reduced expression of ethylene biosynthesis and signaling-related genes up to an optimal level, with an induction of antioxidant enzymatic genes by endophytic co-inoculation in M. oleifera plants under water deficit, suggesting their role in drought stress tolerance as an essential regulatory function.ConclusionThe finding may alert scientists to consider the impacts of optimal reduction of ethylene and induction of antioxidant potential on drought stress tolerance in M. oleifera. Hence, the present study supports the use of compatible endophytic fungi to build a bipartite mutualistic symbiosis in M. oleifera non-host plants to mitigate the negative impacts of water scarcity in arid regions throughout the world.

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