Bt Research 2024, Vol.15, No.1, 42-52 http://microbescipublisher.com/index.php/bt 42 Review and Progress Open Access Bt Toxin-Receptor Interactions: Advances in Understanding Insect Specificity Ming Li, Shusheng Liu, Minsheng Lin Hainan Tropical Agricultural Resources Research Institute, Tropical Microbial Resources Research Center, Sanya, 572025, Hainan, China Corresponding author: minsheng.lin@hitar.org Bt Research, 2024, Vol.15, No.1 doi: 10.5376/bt.2024.15.0005 Received: 20 Dec., 2023 Accepted: 30 Jan., 2024 Published: 15 Feb., 2024 Copyright © 2024 Li et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Li M., Liu S.S., and Lin M.S., 2024, Bt toxin-receptor interactions: advances in understanding insect specificity, Bt Research, 15(1): 42-52 (doi: 10.5376/bt.2024.15.0005) Abstract The Bt toxin produced byBacillus thuringiensis (Bt) has been widely used in agricultural pest management because of its efficient insect targeting and relatively low impact on environmental and non-target organisms. These toxins are able to specifically bind to the receptors of insect intestinal cells, triggering insect death. With increasing reports of pests developing resistance to existing Bt crops, studying toxin-receptor interactions will not only help us design new or improved Bt toxins, but also help us predict and manage the development of pest resistance to these toxins. This study synthesizes the latest understanding of Bt toxin-receptor interactions, focusing on the structural and functional aspects of these proteins and their insect targets. The diversity and complexity of these interactions in different insect groups are highlighted through several case studies, particularly in Lepidoptera and Coleoptera. This study aims to uncover the molecular mechanisms that affect the specificity of these interactions and explore their practical applications in pest management. The significance of this research is not only to promote the in-depth research of basic science, but also to guide the practice of agricultural pest management, especially in the development of new Bt biopesticides and the development of pest resistance management strategies. Keywords Bt toxin; Insect receptor; Toxin-receptor interaction; Insect specificity; Pest management 1 Introduction Bacillus thuringiensis (Bt) is a bacterium known for its insecticidal properties, primarily due to the production of Cry and Cyt toxins. These toxins have been extensively utilized in agricultural biotechnology, particularly in the development of transgenic crops that express Bt toxins to control insect pests. The three-domain Cry (3d-Cry) toxins are among the most studied, with their mode of action involving binding to specific receptors in the insect midgut, leading to pore formation and cell death (Pardo-López et al., 2013). The effectiveness of Bt toxins has significantly reduced the reliance on chemical insecticides, promoting a more sustainable approach to pest management (Pardo-López et al., 2013; Wang et al., 2019). Understanding the interactions between Bt toxins and their insect receptors is crucial for several reasons. Firstly, it helps in elucidating the mechanism of action of these toxins, which is essential for improving their efficacy and specificity (Liu et al., 2022). Secondly, knowledge of these interactions can aid in managing and mitigating the development of resistance in insect populations. Resistance to Bt toxins, such as mutations in cadherin, APN, and ABC transporter genes, poses a significant threat to the long-term effectiveness of Bt crops (Heckel, 2012). By identifying and characterizing new receptors and understanding their role in toxin binding, researchers can develop novel Bt toxins or modify existing ones to overcome resistance (Li et al., 2017; Chen et al., 2021). The study aims to provide a comprehensive overview of the current understanding of Bt toxin-receptor interactions, with a focus on the advances made in identifying and characterizing these receptors. We will discuss the different types of receptors involved, such as cadherins, ABC transporters, and other midgut proteins, and their role in the mode of action of Bt toxins. Additionally, we will explore the mechanisms of resistance that insects have developed and the strategies being employed to counteract this resistance, including the development of new Bt toxins and the use of chimeric proteins. By synthesizing the latest research findings, this review aims to
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