Legume Genomics and Genetics 2024, Vol.15, No.3, 126-139 http://cropscipublisher.com/index.php/lgg 127 This study aims to provide a comprehensive overview of the innovations and impacts of genomic tools in soybean breeding. The specific objective is to examine the historical context and evolution of soybean breeding practices, highlighting the transition from traditional methods to the adoption of genomic technologies; To explore the various genomic tools employed in soybean breeding, including marker-assisted selection, genomic selection, and genome editing, and their specific applications; To assess the impact of these genomic innovations on soybean breeding outcomes, such as yield improvement, disease resistance, and environmental adaptability; To discuss future prospects and challenges in the integration of genomic tools in soybean breeding, identifying potential areas for further research and development. By addressing these objectives, the study aims to elucidate the transformative role of genomic tools in soybean breeding and their broader implications for modern agriculture. 2 Historical Background of Soybean Breeding 2.1 Traditional breeding methods Traditional soybean breeding methods have their roots in China, where soybean (Glycine max) originated over 5 000 years ago. The early domestication and artificial selection practices focused on selecting plants with desirable traits such as higher yield, disease resistance, and better adaptability to local climates. These methods predominantly involved mass selection and simple crossbreeding techniques to improve soybean varieties. The breeding process was labor-intensive and time-consuming, relying heavily on phenotypic selection and natural variation within the soybean population. The use of hybridization techniques, where two different parent plants are crossbred to combine desirable traits, became more refined over time. The Single Seed Descent (SSD) method emerged as a popular technique, where only one seed from each plant is selected for the next generation. This method allowed for more controlled and efficient breeding processes, reducing space and labor requirements while maintaining genetic diversity. Despite these advancements, traditional breeding methods had limitations. For instance, they often resulted in a narrow genetic base, making crops more susceptible to diseases and environmental changes. The slow pace of breeding cycles also hindered rapid improvements and adaptability (Zhang et al., 2021). Furthermore, traditional methods were less effective in incorporating complex traits such as stress resistance and nutritional improvements. 2.2 Milestones in soybean breeding Soybean breeding has achieved significant milestones that have shaped its global prominence. Early domestication and dissemination of soybean began in China and spread to Korea, Japan, and later to the rest of the world, setting the foundation for modern soybean cultivation. Early efforts focused on adapting the crop to different climatic conditions. Soybean was introduced to North America in the 18th century, with significant cultivation beginning in the early 20th century. This period saw the development of varieties suited to the American Midwest, leveraging the region’s growing conditions. The completion of the soybean genome sequencing in 2010 marked a new era in soybean breeding. This milestone facilitated advances in genomic selection, marker-assisted breeding, and the development of transgenic soybean varieties with enhanced traits such as herbicide tolerance and pest resistance. 2.3 Limitations of conventional breeding techniques Despite the progress made through traditional breeding methods, several limitations persist. Conventional breeding is inherently slow, often requiring several generations to achieve desirable traits due to the reliance on natural genetic variation and phenotypic selection. Traditional breeding often suffers from a narrow genetic base, which can lead to reduced genetic diversity and increased vulnerability to diseases and pests. This limitation has been particularly noted in the genetic bases of soybean cultivars in both the U.S. and China. Conventional methods are less adaptable to rapidly changing environmental conditions, such as climate change, which can adversely affect crop yields and resilience. Additionally, traditional breeding requires significant manual effort in selecting and crossbreeding plants, which can be resource-intensive and impractical for large-scale breeding programs (Silva et al., 2017).
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