Salinity stress alleviation in maize using endophytic fungi isolated from desert trees: physiological and biochemical responses

Abstract

Soil salinization is a critical global challenge that limits agricultural productivity, particularly in arid and semi-arid regions. Endophytic fungi from extreme desert habitats offer a sustainable biological strategy to enhance crop salinity tolerance; however, their mechanistic basis remains poorly understood. Two endophytic fungi, Trichoderma harzianum (T) and Fusarium solani (F), isolated from desert trees ( Haloxylon aphyllum and Tamarix sp.), were inoculated individually and in combination (TF) into maize plants. A completely randomized factorial design with three replicates was employed, incorporating four salinity levels (0, 50, 75, and 100 mM). Growth parameters, physiological traits, biochemical markers, antioxidant enzyme activities, and ion concentrations were also evaluated. Salinity significantly reduced growth traits, including fresh biomass (− 35.9%), dry biomass (− 44.4%), total moisture content (− 34.0%), root-to-shoot ratio (− 67.0%), and greenness index (− 13.2%), while increasing electrolyte leakage (+ 124.2%), malondialdehyde (+ 19.9%), and ion accumulation (Na + and Cl − ) in both cultivars. Inoculation with endophytes mitigated salinity-induced damage, leading to significant increases in growth parameters, such as fresh biomass (+ 10.8%), dry biomass (+ 18.0%), total moisture content (+ 9.3%), root-to-shoot ratio (+ 26.3%), relative water content (+ 5.3%), membrane stability index (+ 19.3%), and greenness index (+ 7.7%). Additionally, endophyte inoculation enhanced antioxidant enzyme activities (CAT + 28.9%, POD + 39.6%, APX + 37.0%, and SOD + 19.0%) and DPPH radical-scavenging activity (+ 21.7%). It also reduced electrolyte leakage (− 25.8%) and malondialdehyde (− 20.3%) while improving ion homeostasis by decreasing Na + and Cl − accumulation in the leaves and roots. The protective effects of the endophytes were more pronounced under higher salinity stress (S3:100 mM NaCl), particularly with the combination of T. harzianum and F. solani . The desert-adapted endophytes T. harzianum and F. solani enhance maize salt tolerance through growth promotion, antioxidant defense reinforcement, osmotic adjustment, and ion homeostasis regulation, demonstrating their strong potential as effective bio-inoculants for sustainable maize cultivation in saline-affected agricultural systems.