First record of Verticillium tricorpus as a causal agent of Verticillium wilt disease in Okra

Symptoms of infection okra plants (Abelmoschus esculentus L.) with Verticillium wilt were recorded during the summer of 2021 in Beni Suef Governorate specifically in Nasser, Beba, and El-Wasta Counties. The symptoms appeared on the external parts of plants, specifically through the alteration of color in the leaves of infected shoots, which transition from a normal color to a light green or yellow hue, had V-shaped chlorotic lesions, loss their turgidity and eventually desiccation, plant stunting and vascular discoloration. The presence of V. tricorpus on okra has not been previously documented. The isolated fungus was identified on the basis of morphological characteristics and molecular traits by utilizing sequencing techniques applied to the internal transcribed space (ITS region) of the ribosomal RNA gene. The analysis of the fungal sequencing data revealed a substantial genetic similarity and close ties between the fungus in question and V. tricorpus by 99.24-100% identity and 97-100% coverage with several strains of V. tricorpus, including the type strain CBS447.54 (NR_126128). The obtained sequences were submitted to the GenBank database and assigned the accession number MZ936483. Pathogenicity test confirmed that V. tricorpus had pathogenic properties, as shown by the appearance of disease symptoms that were similar to those previously noted on okra plants in the surveyed regions. This observation represents the initial documentation of V. tricorpus in relation to the occurrence of Verticillium wilt disease in okra. However, there is currently no information of host resistance to this disease among Egyptian okra cultivars, although it is essential for sustainable disease management. Our study indicate that cultivar of Balady green is more resistance to Verticillium wilt while the Iranian red cv. is more sensitive to infection.