Morphocultural and Molecular Characterization of Athelia Rolfsii Associated with Foot Rot Disease of Gomphrena Globosa – A New Record from India

Globe amaranth is an important floriculture plant grown for the cut flowers. The outbreak of southern blight disease was observed during 2019 in parts of the southern Karnataka. The disease incidence ranged from 9.54 to 21.13%. Disease symptoms include water-soaked lesions on the lower leaves, followed by quick wilting of the whole plant. The fungal pathogen was isolated on potato dextrose agar medium which produced white cottony mycelium with numerous reddish-brown sclerotia developed after 12 days of inoculation. A total of 12 fungal isolates were obtained from infected samples and their identity was established based on micro-morphological studies. Further, three isolates were used for molecular identification by sequencing the ITS-rDNA and tef-1α gene showed 100% sequence similarity with reference sequences. The associated fungal pathogen was identified as Athelia rolfsii. Further, pathogenicity tests were conducted on healthy plants in-vitro and in green house conditions. Typical foot rot disease symptoms were observed after 8 days of post-inoculation. The pathogen was re-isolated and its identity was confirmed. There are no reports of A. rolfsii on globe amaranth. To the best of our knowledge, this is the first report of A. rolfsii associated with southern blight disease of globe amaranth in India.