Drought alters cowpea root endophytic fungal communities and functional characterization reveals plant growth-promoting potential of cultured endophytes

Drought is a major constraint to cowpea productivity, but its effects on root-associated endophytic fungi remain poorly understood. This study investigated how drought influences cowpea root endophytic fungal communities and evaluated the plant growth-promoting potential of cultured fungal endophytes. Internal transcribed spacer (ITS) amplicon sequencing revealed that drought significantly altered fungal community composition. Several fungal taxa, including Aspergillus and Chaetomium , showed numerical differences in abundance under drought, although these taxon-specific differences were not significant after correction for multiple comparisons. In parallel, 13 fungal endophytes were isolated from drought-treated cowpea roots and evaluated for plant growth-promoting traits. The isolates differed in 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and presumptive indole-3-acetic acid (IAA) production, and several promoted wheat seedling growth under polyethylene glycol (PEG)-induced osmotic stress. Selected isolates also enhanced okra pollen germination under osmotic stress. Together, these findings demonstrate that drought alters the cowpea root endophytic fungal community and identify cultured endophytes with promising plant growth-promoting activities. Further evaluation through direct inoculation of cowpea under drought is needed to determine their potential for improving crop performance under water-limited conditions.