Molecular Plant Breeding 2024, Vol.15, No.4, 198-208 http://genbreedpublisher.com/index.php/mpb 205 and breeding technologies can complicate the sharing and utilization of genetic resources (Goldstein et al., 2019; Hao et al., 2020). Ensuring that breeding programs adhere to these regulations while also protecting the rights of breeders and farmers is essential for the sustainable use of exotic germplasm in maize improvement (Jiang et al., 2019; Prasanna et al., 2021). In conclusion, while the incorporation of exotic varieties holds great promise for enhancing maize genetic improvement, it is fraught with challenges related to genetic incompatibility, trait complexity, economic and logistical constraints, and regulatory and IP issues. Addressing these challenges requires a concerted effort involving advanced breeding technologies, robust partnerships, and supportive regulatory frameworks. 8 Future Directions 8.1 Advances in genomic tools and technologies The integration of advanced genomic tools and technologies holds significant promise for the future of maize genetic improvement. Genomic selection (GS) models, for instance, have shown potential in enhancing the rate of genetic gain. The Germplasm Enhancement of Maize (GEM) project has demonstrated that GS can predict genetic gains more effectively than traditional phenotypic selection, with prediction abilities ranging from 0.36 to 0.75 for grain yield and from 0.78 to 0.96 for grain moisture (Rogers et al., 2022). Additionally, the use of genomic best linear unbiased prediction (gBLUP) has achieved high prediction accuracies for traits such as tocochromanols, which are essential for biofortification efforts. These advancements suggest that leveraging genomic tools can significantly enhance the efficiency and effectiveness of breeding programs. 8.2 Potential new sources of exotic germplasm Exploring new sources of exotic germplasm is crucial for broadening the genetic base of maize. Studies have shown that landraces from regions such as Sahel and Coastal West Africa exhibit marked genetic diversity and hold great potential for genetic improvement. These landraces can provide novel alleles that are not present in the current elite germplasm pools, offering opportunities for pre-breeding and the development of new, resilient maize varieties. Furthermore, the incorporation of exotic genes from temperate regions has been shown to improve yield potential and stability in sub-tropical maize populations (Nyoni et al., 2022). 8.3 Strategies for overcoming current limitations To overcome current limitations in maize breeding, several strategies can be employed. One approach is the use of managed-stress screening and selection for key secondary traits, which has been successfully implemented by CIMMYT to develop stress-tolerant maize varieties. Additionally, the adoption of modern breeding tools such as doubled haploid (DH) technology, molecular marker-assisted breeding, and transgenics can enhance breeding efficiency and genetic gains. It is also essential to address the challenges posed by genotype x environment interactions (GEI) by conducting multi-environment trials to identify stable and high-yielding genotypes (Nyoni et al., 2022). 8.4 Collaboration and data sharing among global breeding programs Collaboration and data sharing among global breeding programs are vital for the successful integration of exotic germplasm and the development of improved maize varieties. The GEM project exemplifies the benefits of cooperative efforts between public and private sector breeders in enhancing the genetic diversity of maize. Multi-institutional efforts, particularly public-private alliances, are crucial for ensuring that improved varieties reach vulnerable farming communities and for developing technologies to protect maize crops from emerging biotic threats. By fostering collaboration and sharing data, breeding programs can leverage collective knowledge and resources to achieve greater genetic gains and address global challenges in maize production. In conclusion, the future of maize genetic improvement lies in the continued advancement of genomic tools, exploration of new exotic germplasm sources, implementation of innovative breeding strategies, and fostering of global collaboration. These efforts will collectively contribute to the development of resilient, high-yielding maize varieties that can meet the growing demands of food security and climate resilience.
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