The Role of Endophytic Fungi Isolated from Desert and Saline Soils in the Resistance of Tomato Plants to Fusarium Wilt Disease Caused by the Fungal Pathogen Fusarium oxysporum f. sp. lycopersici

This study was conducted during the period from 15/10/2022 to 1/6/2023 and aimed to isolate endophytic fungi from desert and saline soils in several locations around the city of Basrah in southern Iraq. The fungus Cephaliophora irregularis was isolated from Al-Shawil plant, Cressa cretica; Rhizoctonia solani from Al-quampar plant, Trachomitum venetum, Xenomyrothecium tongaens and Thielavia basicola from Tartia plant, Suaeda aegyptiace and Chaetomium sp. from Jumba (Shweikeh) plant, Fagonia bruguieri. Fungi were identified based on its morphological features and molecularly based on the amplification of internal transcribed spacer (ITS) gene region, using the forward primer ITS1 and the reverse primer ITS4. The nucleotide sequence of endophytic fungi was deposited in the GenBank (NCBI) under the number OM245865.1 for Cephaliophora irregularis with a similarity rate of 99.82% and KX118360.1 for Rhizoctonia solani with a match rate of 95.61% and NR154511.1 for Xenomyrothecium tongaens with a match rate of similarity rate of 95.62% and MT277121.1 for Thielavia basicola with a similarity rate of 96.65% with global isolates deposited in the GenBank. Results obtained showed that the treatment of tomato seeds with fungal suspension of these fungi for 24 hours had a significant effect in reducing incidence and severity of Fusarium wilt disease, and that the best treatment was the treatment of seeds with a nonpathogenic isolate of R. solani, as the incidence and severity of infection decreased from 85.0 and 55.00% in the positive control treatment (inoculated with pathogenic fungus only) to 45.0 and 31.00%, respectively. The results also showed that the treatment of tomato seedlings at the age of 30 days with the fungal suspension of endophytic fungi before transferring them to the greenhouse led to a significant decrease in the infection rate and severity compared to the positive control treatment, as it decreased from 80.0 and 52.00% in the positive control treatment to 25.0 and 23.00% in the seedlings inoculated with C. irregularis. The results also showed a significant increase in the enzyme peroxidase activity and total chlorophyll and an improvement in some growth indicators in all treatments with endophytic fungi compared to the positive control. Keywords: Xerophyte, endophytic fungi, Fusarium wilt, tomato, chlorophyll, PCR.