Molecular Identification and Morphological Characterization of Alternaria solani Causing Potato Early Blight in the Southern Region of Kurdistan – Iraq

Hassan, A. M. and Q. A. Marzani. 2024. Molecular Identification and Morphological Characterization of Alternaria solani Causing Potato Early Blight in the Southern Region of Kurdistan - Iraq. Arab Journal of Plant Protection, 42(1): 13-18. https://doi.org/10.22268/AJPP-001206 Potato early blight caused by Alternaria solani is a common disease wherever potato crop is grown. This research is aimed to identify the early blight pathogen which infects potatoes in the Southern Region of Kurdistan and characterize the existing isolates. Sampling was conducted in different provinces of the Region where infected potato leaves were collected from which the fungal pathogen was isolated and then identified. The microscopic examination revealed that the causal fungus was Alternaria solani. Fungal conidia were multicellular, brown to pale, with 1-6 transverse septa and 1-2 longitudinal septa, with curved beaks of 4.5-11.25 µm long. The identity of the fungus was confirmed by molecular diagnosis using PCR amplification with the aid of species-specific primers, AS1 and AS2. The results revealed that the primers were highly specific for the detection of A. solani. DNA amplicon size generated by PCR was 289 bp for all 31 samples tested in this study. The results of morphological characterization showed the existence of 4 phenotypes. The isolates were different in their morphological and microscopical characteristics such as colony colour and length and width of conidia. Results obtained confirmed that the use of species-specific primers in PCR is an efficient tool for quick and accurate pathogen identification. Keywords: Alternaria leaf blight, PCR, Phenotyping.