Isolation and morphological and molecular identification of important endophyte fungi of Pistacia mutica in Hormozgan province and their effect on increasing salt stress tolerance of California Wonder 3 pepper seedlings

Salinity stress, as one of the most common environmental stresses, reduces the yield of agricultural products, especially vegetables. Microbial endophytes, which are considered as one of the most important microorganisms, increase their yield per unit area by causing genetic, physiological, and ecological changes in their host plants and provide the possibility of developing their cultivation in salty, dry soils or climates with abiotic and biotic stresses. In order to identify endophytic fungi in pistachio plant (Pistacia mutica), during the summer season of 2019, sampling of completely healthy organs of the plant, including the bark of the main trunk, side branches, leaves and roots, was carried out in five regions of Hormozgan province. In this study, 20 fungi were isolated and purified from (Pistacia mutica) tree. Then the purified mushrooms were cultured on PDA culture medium containing salinity concentrations (0.5, 1, 2, and 3 mM sodium chloride) and finally three mushrooms that were able to grow at the highest salinity level were selected. Based on the morphological characteristics and sequencing of the ribosomal ITS region, three species of Aspergillus niger MG890603, Paecilomyces formosus MG904988 and Alternaria alternata MG907039 were identified as endophytic fungi from the tuber plant in Iran and the world. In order to investigate the effect of these endophytic fungi on the salinity tolerance of bell peppers, a factorial experiment was conducted in a completely randomized design. The results showed that the application of endophytic fungi P. formosus and A. alternata increased the root length of pepper seedlings by 1.5 double compared to no inoculation at 60 mM salinity stress. Also, the combination of three endophytic fungi, A. niger, P. formosus, and A. alternata, increased the wet and dry weight of pepper seedlings by 4 and 5.5 double, respectively, compared to no inoculation at 60 mM salinity stress. The highest amount of peroxidase in the combination of fungi (P. formosus and A. alternata) and (P. formosus, A. alternata and A. niger) was 51.41 and 48.65%, respectively, under 60 mM salt stress compared to the control. In the salinity stress of 60 mM, the highest amount of catalase related to the fungal combination (P. formosus and A. alternata) was 15.54% compared to the control. In general, the results show that the use of endophytic fungi increases the growth of pepper plants under salt stress. Therefore, the use of endophytic fungi is suggested as an alternative with high potential as plant growth promoters.