Association of Golovinomyces ambrosiae and Podosphaera xanthii in causing powdery mildew disease of Guizotia abyssinica L.f. Cass in India

Powdery mildew is one of the most important diseases in niger ( Guizotia abyssinica ) in India and Ethiopia. Fungi causing the powdery mildew on niger have previously been reported as Golovinomyces cichoracearum and Sphaerotheca sp., but the involved causative agents have not yet been studied in detail. In the present investigation, powdery mildew infections observed on niger in Hyderabad, India, were analyzed by using morphological and multilocus gene sequence analyses. Results based on anamorph characteristics, amplification products obtained with eleven pairs of primers, including powdery mildew-specific primers, combined sequence analyses of internal transcribed spacer (ITS), 28S rDNA and intergenic spacer (IGS) regions, and sequence variations unequivocally indicated mixed infections caused by Golovinomyces ambrosiae and Podosphaera xanthii . Variation in reaction to powdery mildew was observed, and infections were higher in the Ethiopian accessions compared to the Indian varieties. This constitutes the first report of morphological and molecular analyses that confirm mixed powdery mildew infection of niger caused by G. ambrosiae and P. xanthii , two species with wide host ranges.