Plant Gene and Traits 2024, Vol.15, No.4, 195-206 http://genbreedpublisher.com/index.php/pgt 198 et al., 2022). For example, marker-assisted backcrossing (MABC) has been successfully used to introgress resistance to Fusarium wilt and Ascochyta blight in chickpea, and late leaf spot and nematode resistance in groundnut (Varshney et al., 2013). 4.3 Role of molecular markers in pest and disease resistance breeding Molecular markers play a crucial role in breeding for pest and disease resistance by enabling the identification of genomic regions associated with resistance traits. These markers can be used in various breeding strategies, including MAS, marker-assisted backcrossing (MABC), and genomic selection (GS) (Varshney et al., 2013; Jha et al., 2023). For instance, in common bean, molecular markers have been used to develop resistance to multiple diseases such as angular leaf spot, anthracnose, and common bacterial blight (Meziadi et al., 2016; Jha et al., 2022). The use of next-generation sequencing (NGS) technologies has further enhanced the development of high-density genetic maps and the identification of quantitative trait loci (QTLs) associated with disease resistance, facilitating the rapid development of resistant cultivars (Yang et al., 2012; Kankanala et al., 2019). Additionally, the integration of genomics and functional genomics approaches has helped uncover the molecular mechanisms underlying resistance, providing valuable insights for breeding programs (Kankanala et al., 2019; Jha et al., 2023). 5 Marker-Assisted Selection (MAS) for Disease and Pest Resistance 5.1 Overview of MAS in legume breeding programs Marker-assisted selection (MAS) has revolutionized legume breeding programs by enabling the precise and efficient selection of desirable traits, particularly those related to disease and pest resistance. MAS leverages molecular markers linked to specific genes or quantitative trait loci (QTLs) to facilitate the identification and incorporation of resistance traits into new cultivars. This approach has been particularly beneficial in legumes, where traditional breeding methods are often hampered by the complex inheritance patterns of resistance traits and the influence of environmental factors on phenotypic expression (Varshney et al., 2013). 5.2 Identification and use of molecular markers linked to resistance genes The identification of molecular markers linked to resistance genes is a critical step in MAS. Various types of markers, such as simple sequence repeats (SSRs), amplified fragment length polymorphisms (AFLPs), and restriction fragment length polymorphisms (RFLPs), have been employed to map resistance genes in legumes. For instance, in common bean, markers linked to resistance genes for diseases like angular leaf spot, anthracnose, and Bean common mosaic virus have been identified and utilized in breeding programs. Similarly, in lupin, markers linked to anthracnose resistance have been developed and validated for use in MAS. These markers enable breeders to select for resistance traits even in the absence of the pathogen, thereby accelerating the breeding process and improving the efficiency of resistance gene incorporation (Wu et al., 2022). 5.3 Success stories of MAS in improving pest and disease resistance in legume crops Several success stories highlight the effectiveness of MAS in enhancing pest and disease resistance in legume crops. In mung bean, MAS has been used to introgress bruchid resistance genes, resulting in the development of new resistant cultivars with improved agronomic traits (Wu et al., 2022). In chickpea, MAS has facilitated the incorporation of resistance to Fusarium wilt and Ascochyta blight, significantly improving the resilience of new cultivars to these devastating diseases (Varshney et al., 2013). Additionally, the use of MAS in common bean has led to the successful pyramiding of multiple resistance genes, providing broad-spectrum resistance to various pathogens and pests. These examples underscore the potential of MAS to transform legume breeding by enabling the rapid and precise development of resistant cultivars, ultimately contributing to increased crop productivity and food security (Alkimim et al., 2017). 6 Genomic Selection (GS) in Legume Breeding for Resistance 6.1 Principles and applications of genomic selection Genomic selection (GS) is a modern breeding approach that leverages genome-wide marker data to predict the breeding values of individuals, thereby facilitating the selection of superior genotypes. Unlike traditional marker-assisted selection, which focuses on identifying individual loci associated with traits, GS uses all available marker data to predict the overall genetic potential of an individual (Crossa et al., 2017; Budhlakoti et al., 2022).
RkJQdWJsaXNoZXIy MjQ4ODYzMg==