Pathogenicity, host range and activities of a secondary metabolite and enzyme from Myrothecium roridum on water hyacinth from Thailand

Abstract

Leaf blight disease of water hyacinth was observed and collected from different geographical areas of Thailand. The disease is caused by a fungal pathogen that was identified as Myrothecium roridum by using its morphological characteristics. The most effective fungal strains were evaluated for pathogenicity on water hyacinth under greenhouse and natural conditions. Myrothecium roridum isolate, Kamphaeng Sean Campus (KKFC) 448, was found to be the most virulent. Different fungal formulations were evaluated for their level of control of water hyacinth. The results showed that spore suspensions with 10% palm oil or 1% Tween 20 caused a higher level of disease severity, compared to spores applied in water alone. The host range of KKFC 448 was evaluated by using 77 plant species that belong to 40 plant families. The fungus did not cause disease on 74 economically important plants but did produce disease signs on water hyacinth and two other aquatic weeds, duckweed and water lettuce. Leaf blight occurs on water hyacinth leaves after being treated with crude extracts of M. roridum and it was indicated that secondary metabolites were released from the fungal mycelia. Myrothecium roridum that was grown on boiled paddy rice produced β‐1,4‐exoglucanase, β‐1,4‐endoglucanase, β‐glucosidase, xylanase and pectinase more than Mroridum that was grown on potato dextrose agar. The results indicated that M. roridum is a pathogen of water hyacinth and the fungus is capable of producing different enzymatic activities on potato dextrose agar and boiled paddy rice, which might be important for infection.