Endophytic Fungi from Saline and Arid Coastal Regions: Characterization and Potential As Bioinoculants for Crop Enhancement

Mediterranean agriculture is increasingly threatened by climate change, with rising temperatures, prolonged droughts and pest outbreaks reducing crop productivity and sustainability. Endophytic fungi, particularly dark septate endophytes (DSEs), are emerging as promising allies to enhance plant resilience against abiotic and biotic stress. This study isolated 415 endophytic fungi from halophytic and xerophytic plant roots in arid, saline environments. From these, 52 isolates-mainly DSEs-were selected based on morphology and evaluated for antagonism against 15 phytopathogens, plant growth-promoting traits (IAA and siderophore production, phosphate and potassium solubilization), enzymatic activity, biofilm formation and fungicide compatibility. Molecular identification (BLAST) placed the isolates in 11 Ascomycota families plus one oomycete (Pythiaceae). Most isolates showed strong antagonism (>75%) and did not cause disease symptoms in tomato, pepper or bean seedlings; instead, they significantly increased shoot and/or root biomass under controlled conditions. Many produced amylase, cellulase, chitinase and ligninolytic enzymes, and several formed biofilms. Copper oxychloride, metrafenone and prothioconazole were fully compatible with the isolates, whereas azoxystrobin, flutriafol and difenoconazole + cyflufenamid were mostly toxic. These results highlight the potential of specific endophytic fungi as multifunctional bioinoculants for sustainable agriculture in environments affected by salinity and drought.