ISOLATION, PURE CULTURE ACQUISITION, AND MICROSPOPIC IDENTIFICATION OF THE PHYTOPATHOGENIC FUNGUS ALTERNARIA FROM INFECTED PLANT TISSUES

Phytopathogenic fungi of the genus Alternaria are major causal agents of various plant diseases, causing substantial pre- and post-harvest economic losses globally. This study focuses on the systematic isolation, pure culture establishment, and morphological identification of Alternaria strains from symptomatic plant tissues. Infected leaves exhibiting typical concentric target-board necrotic spots were surface-sterilized using sodium hypochlorite, rinsed in sterile distilled water, and inoculated onto Potato Dextrose Agar (PDA). Following incubation at 25±2 ℃ emerging fungal colonies were purified using the single-spore and hyphal tip isolation techniques. Microscopic examination of the pure cultures under a light microscope revealed typical dark-pigmented (dematiaceous), septate mycelia and characteristic obclavate, muriform conidia bearing longitudinal and transverse septa, often arranged in chains. These distinct morphological diagnostic traits reliably confirmed the isolated strain as belonging to the genus Alternaria. The obtained pure cultures serve as a valuable reference collection for subsequent physiological, molecular, and pathological assays.