Bt Research 2024, Vol.15, No.2, 96-109 http://microbescipublisher.com/index.php/bt 97 This study evaluates the current gene stacking strategies employed to enhance the durability of Bt crops. By summarizing the mechanisms of action and resistance associated with different Bt toxins, assessing the effectiveness of various gene stacking approaches in delaying resistance development, identifying potential challenges and limitations in the implementation of gene stacking strategies, and providing recommendations for future research and regulatory policies, the study aims to support the sustainable use of Bt crops. By synthesizing existing literature on gene stacking strategies, this study provides a comprehensive understanding of best practices for enhancing the durability of Bt crops, ensuring their continued success in agricultural pest management. 2 Concept of Gene Stacking 2.1 Definition and principles Gene stacking refers to the process of introducing multiple genes of interest into a single plant genome to combine various desirable traits. This technique is increasingly popular in biotechnology for enhancing crop performance by integrating multiple traits such as insect resistance, herbicide tolerance, and stress resilience. The resulting plants, known as biotech stacked or simply stacked crops, exhibit a combination of traits that provide a significant genetic and agronomic boost, enabling them to thrive in challenging farming conditions (Shehryar et al., 2019; Aparna et al., 2021). The principles of gene stacking involve the precise integration of multiple transgenes into specific genomic locations to ensure stable and high-level expression without disrupting native gene functions. This can be achieved through various methods, including gene pyramiding, recombinase-mediated integration, and the use of designed nucleases for targeted DNA double-strand breaks and subsequent repair (Hou et al., 2014; Petolino and Kumar, 2016; Srivastava and Thomson, 2016). These techniques allow for the sequential addition of genes, creating a cumulative effect that enhances the overall performance and durability of the crops. 2.2 Historical development The concept of gene stacking has evolved significantly over the past few decades. Initially, the focus was on single-gene transformations to confer specific traits such as herbicide resistance or pest tolerance. However, the limitations of single-gene approaches, particularly in addressing complex traits like yield and stress tolerance, led to the development of multi-gene stacking strategies (Collier et al., 2018). Early methods of gene stacking involved conventional breeding techniques to combine multiple traits, but these were often time-consuming and inefficient. Advances in genetic engineering and biotechnology have since revolutionized the field, enabling more precise and efficient methods of gene stacking. Techniques such as the use of recombinases, designed nucleases, and Agrobacterium-mediated transformation have paved the way for the development of high-efficiency gene stacking systems (Hou et al., 2014; Srivastava and Thomson, 2016; Collier et al., 2018). These advancements have made it possible to introduce multiple genes into crops, resulting in enhanced disease resistance, improved yield, and greater adaptability to environmental stresses (Shehryar et al., 2019; Zhao et al., 2023). 2.3 Types of gene stacking Gene stacking can be categorized into several types based on the methods used and the traits targeted. One common approach is gene pyramiding, which involves the sequential addition of genes to achieve a cumulative effect. This method is particularly effective for enhancing resistance to pests and diseases by combining multiple resistance genes into a single crop variety (Yang et al., 2011; Fuchs, 2017). Another type of gene stacking involves the use of recombinase-mediated integration, where specific recombination sites are introduced into the plant genome to facilitate the precise insertion of multiple genes. This method allows for the repeated addition of genes at the same genomic location, ensuring stable expression and minimizing the risk of gene silencing (Hou et al., 2014; Srivastava and Thomson, 2016). Additionally, designed nucleases can be used to create targeted DNA double-strand breaks, enabling the precise integration of transgenes and the creation of stacked products with high-level and stable expression (Petolino and Kumar, 2016).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==