Abstract:Natural products, which feature complex structures and diverse activities, are important sources of new drugs. The research on the biosynthesis pathways of natural products is conducive to exploring the synthesis mechanism catalyzed by enzymes and promoting the application of complex natural products. The corresponding gene clusters regulate the biosynthesis of natural products, and a large number of biosynthetic gene clusters (BGCs) of natural products are not expressed or expressed at low levels in wild-type strains. Thus, these gene clusters are usually cloned before further research on them. It remains challenging to clone and express large gene clusters for the discovery of novel natural products. Construction of genomic library, transformation-associated recombination (TAR), and Red/ET recombination technology are essential techniques for cloning large gene clusters. This study summarizes the research on these three cloning techniques from the aspect of cloning strategy and application. Moreover, we discuss the challenges in cloning large gene clusters, providing a methodological reference for further study.