Maize Genomics and Genetics 2025, Vol.16, No.4, 229-238 http://cropscipublisher.com/index.php/mgg 229 Feature Review Open Access Application of Base Editing in Maize for Herbicide Resistance Improvement Xiaojing Yang, Han Liu Modern Agricultural Research Center, Cuixi Academy of Biotechnology, Zhuji, 311800, Zhejiang, China Corresponding author: han.liu@cuixi.org Maize Genomics and Genetics, 2025, Vol.16, No.4 doi: 10.5376/mgg.2025.16.0020 Received: 23 Jun., 2025 Accepted: 10 Aug., 2025 Published: 28 Aug., 2025 Copyright © 2025 Yang and Liu, 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: Yang X.J., and Liu H., 2025, Application of base editing in maize for herbicide resistance improvement, Maize Genomics and Genetics, 16(4): 229-238 (doi: 10.5376/mgg.2025.16.0020) Abstract Herbicide resistance is a critical challenge in maize (Zea mays L.) production, often leading to yield loss and increased production costs. In this study, we explored the application of base editing technology as a precise genome modification approach to improve herbicide resistance in maize. We first reviewed the principles of cytosine and adenine base editors, highlighting their ability to induce targeted point mutations without double-strand breaks and their advantages over traditional CRISPR-Cas9 systems. Target genes associated with herbicide action pathways, such as acetolactate synthase (ALS) and 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), were identified, and strategies for multiplex editing to broaden resistance profiles were discussed. We proposed application strategies, including the selection of monocot-compatible editor variants, optimization of delivery methods, and validation via molecular and phenotypic assays. A case study on ALS gene base editing demonstrated successful point mutation introduction, resulting in enhanced herbicide resistance and stable agronomic performance. Our findings underscore the potential of base editing to deliver precision, shorter breeding cycles, and the ability to stack multiple resistance traits, while addressing challenges such as off-target effects and regulatory considerations. This work lays the foundation for integrating base editing with advanced breeding tools to promote sustainable maize production and reduce chemical herbicide dependence. Keywords Base editing; Maize; Herbicide resistance; ALS gene; Genome modification 1 Introduction At present, the problem of weeds remains the main threat to global corn production. To solve this problem, farmers usually use herbicides to control weeds. However, the excessive and frequent use of herbicides has led some weeds to evolve resistance (Chen, 2024). As a result, the effectiveness of herbicides deteriorates, which also has an impact on food security. Moreover, the few new ways of herbicide action, coupled with increasingly strict policy supervision, all these have made the management of weeds in corn more difficult (Hussain et al., 2021; Kuang et al., 2024). Previously, researchers used some traditional genetic methods, such as genetic modification or random mutagenesis, to breed herbicide-resistant corn varieties. Although these methods can bring resistance, they also have many problems, such as low efficiency, the possibility of unexpected changes, as well as some policy restrictions and public non-acceptance. In addition, the commonly used gene editing tools nowadays, such as CRISPR/Cas9, will cause breaks in DNA, and then the genes can be modified by the cells' self-repair or by adding templates (Zhou and Liang, 2024). This approach is not only inefficient but also difficult to precisely control mutation points (Zhu et al., 2000; Li et al., 2020; Kaul et al., 2024). In contrast, base editing is a new type of gene editing technology. It can directly and permanently modify a certain base without cutting DNA or adding an external template. In corn, scientists have successfully made precise point mutations on key genes such as ALS (acetyllactate synthase) and EPSPS (5-enolacetone shikimic acid-3-phosphate synthase) using cytosine editors and adenine editors. This enables corn to tolerate sulfonylurea and glyphosate herbicides very well, with almost no impact on yield (Dong et al., 2021; Qiao et al., 2022). This approach also makes it possible to breed new corn varieties that do not carry exogenous genes and are precisely edited.
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