Molecular Plant Breeding 2024, Vol.15, No.6, 340-350 http://genbreedpublisher.com/index.php/mpb 341 FER and GER tolerance in maize and to explore the potential to improve maize yield and disease resistance traits by integrating refined QTLS into genomics-assisted breeding strategies to develop superior maize varieties with enhanced ear rot resistance and reduced mycotoxin accumulation. This study hopes to contribute to the development of sustainable and effective strategies for the management of ear rot in maize, ultimately improving crop yield and quality while ensuring food safety. 2 Ear Rot Disease in Maize: Overview and Challenges 2.1 Pathogens causing ear rot in maize Ear rot in maize is primarily caused by fungal pathogens, with Fusarium species being the most prevalent and destructive. Fusarium verticillioides andFusarium graminearumare the main culprits, leading to Fusarium ear rot (FER) and Gibberella ear rot (GER), respectively. These pathogens not only reduce grain yield and quality but also contaminate the maize with harmful mycotoxins such as fumonisins and deoxynivalenol (DON), posing significant health risks to humans and animals (Lanubile et al., 2017; Yao et al., 2020; Zhou et al., 2021; Akohoue and Miedaner, 2022). 2.2 Economic impact and yield loss due to ear rot The economic impact of ear rot diseases in maize is substantial. Yield losses can reach up to 30% annually due to these fungal infections. The contamination of maize with mycotoxins further exacerbates the economic burden by reducing the marketability and safety of the grain. Infected maize is often unsuitable for consumption, leading to significant financial losses for farmers and the agricultural industry (Lanubile et al., 2017; Akohoue and Miedaner, 2022; Sobiech et al., 2022). The presence of mycotoxins also necessitates additional costs for testing and mitigation, further straining economic resources (Yao et al., 2020). 2.3 Current management strategies and their limitations Current management strategies for ear rot in maize include chemical treatments, agronomic practices, and breeding for resistant varieties. However, these methods have several limitations. While fungicides can reduce the incidence of ear rot, they are often not entirely effective and can increase production costs. Additionally, the overuse of chemicals can lead to environmental concerns and the development of resistant fungal strains (Lanubile et al., 2017). Practices such as crop rotation, proper irrigation, and timely harvesting can help manage ear rot, but they are not foolproof. Environmental factors and the persistent nature of Fusarium spores can still lead to outbreaks despite these measures (Lanubile et al., 2017; Sobiech et al., 2022). Genetic resistance is considered the most sustainable approach. Significant progress has been made in identifying quantitative trait loci (QTL) and candidate genes associated with resistance to FER and GER. However, the polygenic nature of resistance and the influence of environmental factors make breeding for resistance a complex and ongoing challenge (Ali et al., 2005; Ding et al., 2008; Wu et al., 2020). 3 QTL Mapping: Concept and Importance in Plant Breeding Quantitative trait loci (QTL) mapping is a powerful tool in plant breeding, particularly for identifying genetic regions associated with complex traits such as disease resistance and yield (Takuno et al., 2012; Dhingani et al., 2015). This section delves into the definition, principles, and applications of QTL mapping, with a focus on its role in improving maize resistance to ear rot diseases (Jiménez-Galindo et al., 2017). 3.1 Definition and principles of QTL mapping QTL mapping is a statistical method used to identify regions of the genome that are associated with specific quantitative traits. These traits are typically controlled by multiple genes and influenced by environmental factors. The process involves crossing two parent lines that differ in the trait of interest, followed by genotyping and phenotyping their offspring. By analyzing the correlation between genetic markers and phenotypic variation, researchers can pinpoint the genomic regions, or QTLs, that contribute to the trait. 3.2 Role of QTL mapping in identifying resistance traits QTL mapping plays a crucial role in identifying genetic loci associated with resistance to diseases such as Fusarium and Gibberella ear rots in maize. These diseases significantly reduce yield and grain quality by
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