Maize Genomics and Genetics 2025, Vol.16, No.1, 34-44 http://cropscipublisher.com/index.php/mgg 38 Nutritional components such as proteins, vitamins, and anthocyanins are critical for the health benefits of fresh corn. Studies have shown that agronomic traits like flowering time and plant height can have positive linear relationships with nutritional traits such as crude protein and starch content (Alves and Filho, 2017). The presence of favorable alleles at specific QTLs can enhance these nutritional components, making certain maize varieties more nutritious (Ragot et al., 1995). Furthermore, the evaluation of these traits across various environments helps in identifying stable and high-quality germplasm resources that can be used in breeding programs to improve the nutritional value of fresh corn (Ragot et al., 1995; Mansfield and Mumm, 2014). 4.3 Stress resistance evaluation Resistance to diseases such as rust and leaf spot is a critical factor in evaluating fresh corn germplasm resources. For instance, southern corn rust (SCR) caused by Puccinia polysora is a significant disease affecting maize yields. A study identified several quantitative trait nucleotides (QTNs) associated with SCR resistance in Chinese summer maize germplasm. These QTNs were linked to various genetic loci and were validated through post-GWAS analysis, highlighting their potential in breeding programs aimed at enhancing disease resistance (Shu et al., 2023). Additionally, resistance to mycotoxin contamination, such as aflatoxins and fumonisins, has been evaluated under different stress conditions. Aflatoxin-resistant germplasm lines showed significantly lower contamination levels compared to commercial hybrids, especially under high heat stress, indicating their superior resistance to fungal diseases (Abbas et al., 2002). Abiotic stresses such as drought, salinity, and high temperatures significantly impact maize productivity. The relationship between aflatoxin contamination and physiological responses of corn plants under drought and heat stress has been studied extensively. For example, certain germplasm lines like PI 639055 demonstrated low aflatoxin contamination despite being highly stressed, suggesting inherent tolerance mechanisms (Kebede et al., 2012). This tolerance is crucial for maintaining yield and quality in environments prone to abiotic stresses. 4.4 Molecular-level evaluation Genetic diversity analysis using molecular markers is essential for understanding the genetic basis of stress resistance in maize. Multi-locus genome-wide association studies (GWAS) have been employed to identify QTNs associated with disease resistance traits. For instance, in the study of SCR resistance, 13 QTNs were identified across multiple chromosomes, providing insights into the genetic diversity and potential for breeding resistant varieties (Shu et al., 2023). The identification of QTLs associated with target traits such as disease resistance and stress tolerance is a pivotal aspect of molecular-level evaluation. In the case of SCR resistance, the identified QTNs were linked to candidate genes involved in transcriptional regulation, phosphorylation, and temperature stress response. These findings underscore the importance of QTL mapping in developing germplasm with enhanced resistance to both biotic and abiotic stresses (Shu et al., 2023). 5 Advances in Fresh Corn Breeding Techniques 5.1 Traditional breeding methods Traditional breeding methods in fresh-eating maize primarily involve hybridization and backcrossing to improve target traits. Hybridization combines desirable traits from two parent plants to produce offspring with enhanced characteristics, such as increased sweetness or disease resistance. Backcrossing, on the other hand, involves crossing a hybrid with one of its parent plants to reinforce specific traits. These methods have been fundamental in developing new maize varieties with improved yield, taste, and resilience to environmental stresses. 5.2 Marker-assisted selection (MAS) and genomic selection (GS) Marker-assisted selection (MAS) and genomic selection (GS) have revolutionized the breeding process by accelerating the development of superior maize varieties. MAS utilizes molecular markers linked to desirable traits to assist in the selection process, significantly speeding up the breeding cycle. For instance, MAS has been effectively used to improve drought adaptation in maize by introgressing favorable alleles at target regions, resulting in hybrids with higher grain yield under water-limited conditions (Francia et al., 2005; Ribaut and Ragot,
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