مطالعه تاثیر توکسین های جدایه های Alternaria برگیاه آفتابگردان و گوجه فرنگی

Alternaria spp. is considered one of the most important plant pathogens that causes disease in many crops and ornamental plants. Mycotoxins, known as fungal secondary metabolites with low molecular weight and complex chemical structures, are produced by many plant-pathogenic fungi. These metabolites are effective on the pathogenicity of fungi in plants. This study was conducted to investigate the effect of mycotoxins on some pathogenic isolates of Alternaria spp. and isolated from soil on sunflower and tomato. Identification of Alternaria isolates that were isolated using the Zapek medium was done by morphological and molecular methods. To produce toxin, the pathogen was cultured in a PDB medium and incubated at 25°C for three weeks. After removing the fungus from the media, the toxin was extracted by using a centrifuge and adding chloroform-acetone in a ratio of 80:20. A two-phase solution was formed, the lower phase of which contained chloroform-acetone, and this phase was used to continue the study. The precipitated chloroform phase was extracted and transferred into other dishes so that its chloroform evaporated. HPLC method (high-performance chromatography) was used to identify mycotoxins. Then 1 CC of distilled water was added to the dry material and its effect on the mentioned plants was checked by injecting it into the leaves. Based on the morphological and molecular characteristics, the toxin-producing isolates all belonged to Alternaria spp., which produced Tenuazonic acid (TEA), Tentoxin (TTX), and Altenune (ALT) toxins. Toxins injected into sunflower tissue after 6 days led to chlorosis and necrosis in plant leaf tissue, but symptoms were visible on tomato plants after three days.