Cry75Aa (Mpp75Aa) insecticidal proteins for controlling the western corn rootworm, diabrotica virgifera virgifera leconte (coleoptera: chrysomelidae), isolated from the insect-pathogenic bacterium brevibacillus laterosporus

Authors: BOWEN, DAVID - Bayer Cropscience; YIN, YONG - Bayer Cropscience; FLASINKSI, STANISLAW - Bayer Cropscience; CHAY, CATHY - Bayer Cropscience; BEAN, GREG - Bayer Cropscience; MILLIGAN, JASON - Bayer Cropscience; MOAR, WILLIAM - Bayer Cropscience; PAN, AIHONG - Bayer Cropscience; WERNER, BRENT - Bayer Cropscience; BUCKMAN, KARRIE - Bayer Cropscience; HOWE, ARLENE - Bayer Cropscience; CICHE, TODD - Bayer Cropscience; TURNER, KEITH - Bayer Cropscience; PLEAU, MIKE - Bayer Cropscience; ZHANG, JUN - Bayer Cropscience; KOUADIO, JEAN-LOUIS - Bayer Cropscience; Hibbard, Bruce; PRICE, PAULA - Bayer Cropscience; ROBERTS, JAMES - Bayer Cropscience

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2020
Publication Date: 2/12/2021
Citation: Bowen, D., Yin, Y., Flasinksi, S., Chay, C., Bean, G., Milligan, J., Moar, W., Pan, A., Werner, B., Buckman, K., Howe, A., Ciche, T., Turner, K., Pleau, M., Zhang, J., Kouadio, J., Hibbard, B.E., Price, P., Roberts, J. 2021. Cry75Aa (Mpp75Aa) insecticidal proteins for controlling the western corn rootworm, diabrotica virgifera virgifera leconte (coleoptera: chrysomelidae), isolated from the insect-pathogenic bacterium brevibacillus laterosporus. Applied and Environmental Microbiology. 87(5). Article e02507-20. https://doi.org/10.1128/AEM.02507-20.
DOI: https://doi.org/10.1128/AEM.02507-20

Interpretive Summary: The western corn rootworm is one of the most economically important insect pests in North America. Since 2003, transgenic maize expressing rootworm-active proteins from Bacillus thuringiensis (Bt) have been widely adopted as the main approach to controlling rootworm in the U.S. However, the emergence of field resistance to these proteins has been documented in recent years, highlighting the need to develop additional tools for controlling this devasting pest. Here, the insecticidal activities of Cry75Aa1, Cry75Aa2 and Cry75Aa3 were determined by feeding WCR larvae an artificial diet overlaid with preparations of each of the proteins expressed separately in recombinant bacteria. The genes, designed to express the mature form of Cry75Aa (mCry75Aa), were independently transformed into, and expressed in maize. Transgenic plants expressing each mCry75Aa protein were protected from feeding damage by WCR larvae and showed significant reductions in adult beetle emergence from infested plants. The transgenic maize events that were protected from susceptible larval feeding damage and had reduced adult emergence, also exhibited protection from root feeding damage when infested with WCR resistant to current commercial Bt traits, Cry3Bb1 and Cry34Ab1/Cry35Ab1. These results demonstrate that proteins similar to the well-known Bacillus thuringiensis insecticidal Cry proteins from B. laterosporus are equally as good at controlling major insect pests. The deployment of transgenic maize expressing mCry75Aa along with other active molecules which lack cross resistance have the potential to be a useful tool for control of the WCR populations resistant to current Bt traits.

Technical Abstract: This study describes three closely related proteins cloned from Brevibacillus laterosporus strains that are lethal upon feeding to Diabrotica virgifera virgifera LeConte, the western corn rootworm (WCR). Mpp75Aa1, Mpp75Aa2, and Mpp75Aa3 were toxic to WCR larvae when the larvae were fed purified protein. Transgenic plants expressing each mMpp75Aa protein were protected from feeding damage and showed a significant reduction in adult emergence from infested plants by both susceptible Cry3Bb1 and Cry34Ab1/Cry35Ab1-resistant WCR. These results demonstrate that proteins from B. laterosporus are as efficacious as the well-known Bacillus thuringiensis insecticidal proteins in controlling major insect pests such as WCR. The deployment of transgenic maize expressing mMpp75Aa, along with other active molecules lacking cross-resistance, has the potential to be a useful tool for control of WCR populations resistant to current B. thuringiensis traits. IMPORTANCE Insects feeding on roots of crops can damage the plant roots, resulting in yield loss due to poor water and nutrient uptake and plant lodging. In maize, the western corn rootworm (WCR) can cause severe damage to the roots, resulting in significant economic loss for farmers. Genetically modified (GM) plants expressing Bacillus thuringiensis insect control proteins have provided a solution for control of these pests. In recent years, populations of WCR resistant to the B. thuringiensis proteins in commercial GM maize have emerged. There is a need to develop new insecticidal traits for the control of WCR populations resistant to current commercial traits. New proteins with commercial-level efficacy on WCR from sources other than B. thuringiensis are becoming more critical. The Mpp75Aa proteins from B. laterosporus, when expressed in maize, are efficacious against the resistant populations of WCR and have the potential to provide solutions for control of resistant WCR.