Molecular Plant Breeding 2024, Vol.15, No.5, 282-294 http://genbreedpublisher.com/index.php/mpb 286 insights into the molecular mechanisms underlying drought resistance, facilitating the development of drought-tolerant maize (Liu and Qin, 2021). Additionally, the use of quantitative trait locus (QTL) mapping and genome-wide association studies (GWAS) has enabled the identification of key genes associated with abiotic stress tolerance, which can be introgressed into maize varieties to enhance their resilience (Raj and Nadarajah, 2022). The successful deployment of drought-tolerant maize varieties in regions like Uganda has demonstrated their potential to mitigate the effects of drought and improve yield stability (Habte et al., 2023). Figure 2 Maize germplasm phenotyping/testing network of CIMMYT and partners in the tropics of ESA, Latin America, and Asia (Adopted from Prasanna et al., 2021) 5.4 Nutritional enhancement and biofortification of maize Nutritional enhancement and biofortification of maize through genetic engineering aim to address micronutrient deficiencies and improve the overall nutritional quality of maize. By introducing genes that enhance the biosynthesis of essential nutrients, researchers have been able to develop maize varieties with increased levels of vitamins and minerals. For instance, the integration of alleles associated with desirable agronomic traits, such as enhanced photoperiod and flowering traits, has the potential to improve the nutritional quality of maize (Dwivedi et al., 2017). Furthermore, the use of transgenic and gene editing technologies has enabled the manipulation of metabolic pathways to increase the content of specific nutrients, thereby contributing to the biofortification of maize (Esmaeili et al., 2022). 6 Environmental and Sustainability Impacts 6.1 Reducing the need for chemical inputs: herbicide tolerance and insect resistance Genetic engineering has significantly contributed to reducing the need for chemical inputs in maize cultivation. For instance, genetically engineered (GE) maize varieties with herbicide tolerance and insect resistance have shown a marked decrease in the use of chemical pesticides. A meta-analysis revealed that the adoption of GE crops has led to a 37% reduction in chemical pesticide use, with insect-resistant crops showing more substantial reductions compared to herbicide-tolerant crops (Klümper and Qaim, 2014). Additionally, GE insect-resistant maize has been associated with an 11.2% reduction in insecticide use compared to non-GE varieties (Perry et al., 2016). These reductions not only lower production costs but also minimize the environmental impact of chemical inputs. 6.2 Genetic engineering and its potential role in climate-resilient agriculture Genetic engineering plays a crucial role in developing climate-resilient maize varieties. Efforts by institutions like the International Maize and Wheat Improvement Center (CIMMYT) have led to the development of elite maize
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