Bacillus thuringiensis derived vegetative insecticidal protein Vip3Aa20 as a potential aflatoxin mitigation tool in maize (Zea mays)

Authors: MAYS, TAYLOR - Texas A&M Agrilife; Medrano, Enrique; MAMOUDOU, SETAMOU - Texas A&M University; SCHUSTER, GRETA - Texas A&M University

Submitted to: Research Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2022
Publication Date: 3/30/2022
Citation: Mays, T.D., Medrano, E.G., Mamoudou, S., Schuster, G.L. 2022. Bacillus thuringiensis derived vegetative insecticidal protein Vip3Aa20 as a potential aflatoxin mitigation tool in maize (Zea mays). Research Journal of Plant Pathology. 5(2:05). https://doi.org/10.36648/iprjpp.22.5.005.
DOI: https://doi.org/10.36648/iprjpp.22.5.005

Interpretive Summary: Aflatoxins are a group of chemicals produced by several species of the fungus, Aspergillus, which commonly infect maize plants. Because aflatoxins are known to be potential carcinogens to animals and humans, aflatoxin levels must be below a certain level before maize can be used for feed. Insects are known to play a key role in the Aspergillus infection process of maize. Thus, it has been speculated that controlling insect pests on maize could reduce Aspergillus infection and subsequent aflatoxin levels. We measured aflatoxin levels in maize plants that were genetically modified to produce several Bacillus thuringiensis (Bt) toxins to control insect pests. Compared with non-genetically modified plants, aflatoxin levels in Bt plants were reduced by 50 to 95%. These results suggest that the use of Bt technology to suppress insect pests may also be an effective strategy for reducing aflatoxin contamination in maize.

Technical Abstract: Aflatoxin contamination is an annual profitability challenge for maize (Zea mays) producers in Texas and other portions of the southern United States of America. Insects are known to play a key role in the maize infection process by Aspergillus flavus that produce aflatoxin. Transgenic maize hybrids produce Bacillus thuringiensis (Bt) toxins to reduce the level of aflatoxin contamination. This project evaluated the potential effectiveness of incorporating the Vegetative Insecticidal Protein Vip3Aa20 in an integrated aflatoxin mitigation program. Maize variety trait packages evaluated consisted of a non-Bt, Genuity VT DoublePro, Herculex, Genuity SmartStax, and Leptra which contained the Vip3Aa20 Bt protein. During the 2014 growing season aflatoxin concentrations ranged from 1.408 µg/kg in the Leptra trait package to a high of 45.97 µg/kg in the non-Bt trait package. In comparison, the Leptra trait package significantly reduced the level of aflatoxin compared to all other treatments. In 2015, aflatoxin concentrations ranged from non-detected (<0.0 µg/kg) in the Herculex trait package to a high of 5.64 µg/kg in the Genuity VT Double Pro trait package; statistical differences between treatments were not found. Aflatoxin concentrations in 2016 ranged from <0.0 µg/kg in the Herculex treatment to a high of 45.58 µg/kg in the non-Bt trait package; all Bt trait packages had statistically less aflatoxin contamination than the non-Bt trait suite. Aflatoxin concentrations in the Leptra trait package was lower than the non-Bt by an average of 91.8, 51.64, and 95% during the 2014, 2015, and 2016 growing seasons, respectively. Results from this research illustrated that utilization of the Vip3Aa20 Bt-protein reduced aflatoxin contamination in maize and thus, has a high economic potential.