Insights into the Morphological and Molecular Characteristics of Oidium neolycopersici: A Study from Syria

Powdery mildew poses a global challenge to tomato greenhouse production. In Syria, identification and characterization of the specific fungal species responsible for this disease remain relatively limited. The present study aimed to identify four local isolates of O. neolycopersici (M8, M10, G12, and R12). The morphological features of the four isolates were similar to those of O. neolycopersici based on symptoms, light, and scanning electron microscopy (SEM) observations. The analyses of the internal transcribed spacer (ITS) region confirmed that the four Syrian isolates belong to O. neolycopersici and presented 99–100% sequence similarity with the many other isolates registered in GenBank on tomatoes. Nucleotide sequences and translated nucleotides into amino acids for isolates M8 and M10 were found to be 100% identical, as were isolates G12 and R12. The two groups of isolates differed in only one nucleotide position within the ITS region and in six amino acids. Phylogenetic analysis revealed that the Syrian isolates could be classified into the same cluster group as the Netherlands O. neolycopersici isolate (VPRI20724). To our knowledge, this is the first well-founded report on the protected tomato powdery mildew, O. neolycopersici, in Syria.