Molecular Plant Breeding 2025, Vol.16, No.1, 93-104 http://genbreedpublisher.com/index.php/mpb 97 4.3 Genetic modification and its role in enhancing protein content Genetic modification (GM) offers a powerful tool for enhancing the protein content of maize by directly introducing or modifying genes associated with protein synthesis. Unlike traditional breeding, which relies on the natural variation and recombination of genes, genetic modification allows for the precise insertion of specific genes that can enhance protein content and quality. For instance, genetic engineering techniques have been used to increase the levels of essential amino acids such as lysine and tryptophan in maize kernels, thereby improving their nutritional value (Figure 2) (Amegbor et al., 2022; Sethi et al., 2023). Figure 2 Distribution of MQTLs on different maize chromosomes (Adopted from Sethi et al., 2023) Image caption: Common: MQTLs associated with both quality and yield-associated traits, BFQ: breeder-friendly quality trait MQTLs, BFY: breeder-friendly yield trait MQTLs, BFC: breeder-friendly common MQTLs (involving both quality and yield-related traits) (Adopted from Sethi et al., 2023) One of the key advantages of genetic modification is its ability to overcome the limitations of traditional breeding. For example, while traditional breeding methods may struggle to simultaneously improve multiple traits due to genetic linkage and trade-offs, genetic modification can target specific genes without affecting other traits. This has been demonstrated in studies where genes associated with protein quality and yield-related traits were identified and manipulated to develop biofortified, high-yielding maize varieties (Sethi et al., 2023). However, the adoption of GM maize varieties is often hindered by regulatory, ethical, and public acceptance issues, which need to be addressed to fully realize the potential of this technology in enhancing maize protein content. 5 Environmental Considerations 5.1 Impact of climate on maize protein expression Climate significantly influences the expression of protein in maize. Rising atmospheric CO2 levels have been shown to alter the protein composition of maize, with increases in certain protein fractions like glutelin and zein, while others like globulin and α-zein decrease. These changes can affect the nutritional value of maize, highlighting the need for breeding programs to consider future climate scenarios to maintain or improve protein quality (Wroblewitz et al., 2014). Additionally, climate-induced stresses such as drought and heat can impact
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