Exploring the diversity of fungal root endophytes from saline and agricultural soils: in vitro and in vivo studies on characterization of plant growth promotion traits

We investigated the diversity and plant growth-promoting potential of endophytic fungi isolated from halophilic and halotolerant plant species collected across three saline sites in Algeria. A total of 30 fungal isolates were obtained and subsequently identified through morphological characterization and molecular analysis.The result of Plant Growth Promoting Fungal (PGPF) traits revealed that all tested isolates produced the phytohormone indole-3-acetic acid (IAA). The enzymatic screening revealed that Cellulase and Amylase activities were observed in 30% and 13% of strains, respectively, whereas phosphate solubilization was limited to only two isolates. Antagonistic assays revealed several strains with high efficacy against the pathogen Fusarium oxysporum, achieving inhibition rates of up to 67%. The research also revealed remarkable resilience of 73% of the fungal strains to 20% of NaCl.In vivo inoculation on cucumber plants with four selected endophytes revealed strain-specific effects on growth promotion. Phaeocytostroma plurivorum A27 demonstrated the most pronounced growth-promoting effects, yielding the greatest increases in root length as well as plant fresh and dry biomass. In contrast, Fusarium equiseti A22 conferred only a marginal enhancement in dry weight.In conclusion, these findings highlight the potential of well-adapted endophytic fungi, particularly strain A27, as effective bio-inoculants for enhancing plant growth agricultural systems. Futures research should prioritize evaluating the performance of these native isolates under actual salinity stress to determine their true potential in salt affected environments.