|OKUNOWO, WAHAB - University Of Lagos|
|OSUNTOKI, AKINNYI - University Of Lagos|
|ADEKUNLE, ADEDOTUN - University Of Lagos|
|GBENLE, GEORGE - University Of Lagos|
|SHIER, THOMAS - University Of Minnesota|
Submitted to: Toxin Reviews
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2018
Publication Date: 1/28/2019
Citation: Okunowo, W.O., Osuntoki, A.A., Adekunle, A.A., Gbenle, G.O., Abbas, H.K., Shier, T.W. 2019. Optimization of Myrothecium roridum tode: Fries phytotoxin production and bioactivity on water hyacinth (Eichhornia crassipes). Toxin Reviews. pp.1-15.
Interpretive Summary: Water hyacinth is an economically significant water weed. A fungus (mold) called Myrothecium roridum has been discovered which attacks water hyacinth. This fungus produces a toxic material called roridin A, that causes damage to to some plants and animals. This paper showed that the fungus produces more toxin under some conditions than others. It also showed that the toxin may act as surrogate for the fungus in the control of water hyacinth as well as some factors which may influence its lethal effect on the weed. The work also demonstrated the non-host specific nature of the toxin to water hyacinth and the safety of some agricultural crops. This will help us use this fungus safely to control water hyacinth. More research needs to be conducted outside to further our understanding. This information is useful for other researchers in the field and those trying to control this weed and other weeds in crops and waterways.
Technical Abstract: A study was conducted on the production of phytotoxin using a fungus, Myrothecium roridum Tode: Fries (IMI 394934), isolated from diseased water hyacinth (Eichhornia crassipes) plants collected from Badagry Creek and Ogun River in Lagos State, Nigeria. Phytotoxin produced by the fungus caused necrosis and cell death of water hyacinth leaves three days after toxin inoculation. The effects of various parameters such as light, pH, media, carbon and nitrogen source were evaluated for phytotoxin production and biological activity. Potato carrot broth and a water hyacinth leaf broth formulation gave the highest phytotoxin production in culture. Phytotoxin production was light-dependent and toxin production peaked at pH 4.5. Xylose and glutamine were the best carbon and nitrogen source, respectively. The phytotoxin was thermostable, and the biological activity was pH and photoperiod independent. Qualitative analyses of toxin production by M. roridum indicates that roridin A is the active phytotoxin, consistent with roridin A playing an important role in pathogenesis of water hyacinth by M. roridum.