Maize Genomics and Genetics 2024, Vol.15, No.4, 182-190 http://cropscipublisher.com/index.php/mgg 188 Figure 2 MVs clustering with germplasm from different breeding programs (Adopted from Rojas-Barrera et al., 2019) Image caption: (A): Genotype distribution of MV1 and MV2 sampled in sympatry with LRs. LRs are colored by sampling period: earlier than 1960 (LR<1960), dark blue; between 1960 and 1980 (LR 1960 to 1980); light blue; and later than 2000 (LR>2000), purple; (B): Distribution for MV1, MV2, and the LRs collected for this work with a sample subset from the US national maize inbred seed bank (2 578 genotypes and 13 953 SNPs); (C): Clustering of genotypes colored by the breeding program (1 002 genotypes, 13 953 SNPs); ExPVP, expired plant variety protection. (D) Tropical breeding pools from Mexico, Nigeria, Cameroon, MV1, and MV2 (463 genotypes and 13 953 SNPs) (Adopted from Rojas-Barrera et al., 2019) 7.4 Policy and ethical considerations The findings from gene flow studies also raise important policy and ethical considerations. The introgression of genes from MVs into traditional LRs and WRs can have both positive and negative effects on genetic diversity and crop resilience (Rojas-Barrera et al., 2019). Policymakers need to balance the benefits of modern breeding techniques with the need to protect indigenous genetic resources. Ethical considerations include the rights of local communities to their traditional varieties and the potential impacts of gene flow on these varieties. Developing policies that promote sustainable agricultural practices and the conservation of genetic diversity will be essential for the future of maize cultivation. 8 Concluding Remarks This study has provided a comprehensive overview of the evolutionary dynamics of maize, with a particular emphasis on the role of gene flow in shaping its genetic diversity and adaptation. Various aspects of gene flow were explored, from its impact on genetic diversity, agronomic traits, and pest and disease resistance, to its implications for conservation and breeding strategies. The findings underscore the significant influence of gene flow from modern maize varieties (MVs) to traditional landraces (LRs) and wild relatives (WRs), highlighting its contribution to genetic adaptability and resilience in maize. The studies discussed illustrate how gene flow facilitates the integration of beneficial alleles into maize populations, enhancing their ability to adapt to changing environmental conditions. The incorporation of genes from MVs into LRs and WRs has not only increased genetic diversity but also led to the development of new varieties with improved agronomic and resistance traits. Furthermore, the adaptive introgression events have
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