Control of Tomato Leaf Spot Pathogen Alternaria alternata using Endophyte Fungi Matrood Abdulnabi A A*, Fotouhifar Khalil-Berdi1 Department of Plant Protection, College of Agriculture, University of Basrah, Iraq 1Department of Plant Protection, Faculty of Agriculture, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran *Correspondence: abdul_nabi.matrwod@uobasrah.edu.iq
Online Published on 14 December, 2023. Abstract In laboratory experiments, it was observed that two isolates of A. alternata were capable of infecting tomato seeds on water agar media. Isolate No. 1 exhibited the highest success rate, infecting 63% of the seeds, while isolate No. 2 achieved an infection rate of 56%. Further investigation using PDA culture medium revealed that the filtrate of the bio-resistant fungi, when applied in concentrations of 10, 20, or 30%, exhibited significant suppression of the pathogenic fungus A. alternata. The degree of inhibition increased with higher concentrations. The GC-MS analysis on the fungal filtrates of T. harzianum and T. koningii, identified several chemical compounds with antifungal properties including Oxacycloheptadec-8-en-2-one, compound 9,12-Octadecadienoic acid, methyl ester, and others. The bio-resistant fungi significantly reduced the severity of A. alternata infection. Treatment with T. harzianum led to a reduction of 33.8% in disease severity index (DSI) compared to a reduction of 56.9% when treating with the pathogenic fungus alone. T. koningii treatment on tomato leaves resulted in the highest phenolic content (0.55 mg g-1), as well as the highest catalase activity (CAT = 5.93 units per mg protein per min) and peroxidase activity (5.71 units per g/mL per min). However, it is noted that the combined application of T. koningii and T. harzianum had minimal effects on disease severity index (DSI) and disease incidence (DI), while it increased catalase (CAT) and peroxidase (POX) activities. Therefore, within integrated pest management strategies, the use of biological control agents such as T. koningii and T. harzianum should be considered for effective control of A. alternata. Top Keywords Phenols, Catalase, Trichoderma, Alternaria, Pathogenicity. Top |