Maize Genomics and Genetics 2024, Vol.15, No.2, 70-79 http://cropscipublisher.com/index.php/mgg 73 of genetic variation and population structure (Sun and Wong, 2001) Additionally, species traits related to parental investment, such as longevity and fecundity, have been shown to predict genetic diversity levels, with long-lived or low-fecundity species being less genetically diverse (Romiguier et al., 2014). These findings highlight the complex interplay of ecological, environmental, and biological factors in shaping the genetic diversity of Zea species. 4 Conservation of Zea Genetic Resources 4.1 Threats to genetic diversity inZea The genetic diversity of Zea species, including maize and its wild relatives, faces several threats. One significant threat is the economic pressure favoring genetic monocultures to maximize short-term agricultural gains, which reduces genetic variability and increases vulnerability to pests and climatic extremes. Additionally, the loss of traditional farming practices and the adoption of high-yielding crop cultivars contribute to the erosion of landraces, which are crucial reservoirs of genetic diversity. Habitat destruction and environmental changes further exacerbate the loss of genetic diversity in wild Zea populations. 4.2 Strategies for conservation To mitigate these threats, a combination of in situ and ex situ conservation strategies is essential. In situ conservation involves maintaining genetic resources in their natural habitats, which allows for the preservation of not only the genetic material but also the ecological and evolutionary processes that shape it. Ex situ conservation, on the other hand, involves preserving genetic material in gene banks, seed banks, and other repositories, providing a backup against the loss of genetic diversity in the wild. Both strategies are complementary and necessary for a comprehensive conservation approach. 4.3 Role of gene banks and ex situ conservation Gene banks play a critical role in the ex situ conservation of Zea genetic resources. They provide a secure environment for the long-term storage of genetic material, ensuring that it remains available for future breeding and research efforts. Ex situ collections can capture a significant portion of the genetic diversity found in natural populations, although they may under-represent some rare alleles (Kallow et al., 2021). Regular evaluation and regeneration of gene bank accessions are necessary to maintain genetic diversity and prevent genetic drift (Hintum et al., 2007). Additionally, incorporating genetic material from wild populations into gene banks can enhance the genetic representation and resilience of ex situ collections. 4.4 In situ conservation efforts In situ conservation efforts focus on preserving Zea genetic resources within their natural habitats. This approach maintains the dynamic processes of natural selection and adaptation, which are crucial for the long-term survival and evolution of species. In situ conservation can be achieved through the establishment of genetic reserves, protected areas, and the promotion of traditional farming practices that maintain landrace diversity. For example, the ongoing maintenance of maize landraces by farmers in southern Mexico demonstrates the potential for in situ conservation to coexist with modern agricultural practices. Mapping the geographical distribution of genetic variation can also help identify areas of high diversity and guide conservation efforts. 5 Implications for Breeding 5.1 Utilization of genetic diversity in breeding programs The genetic diversity present in Zea species, including both domesticated maize and its wild relatives, offers a rich reservoir of alleles that can be harnessed for breeding programs. The extensive genetic variation found in maize, as well as in its wild relatives such as teosinte, provides opportunities to introduce novel traits and enhance the genetic base of elite breeding materials (Whitt et al., 2002; Abdoul-Raouf et al., 2017). For instance, the incorporation of alleles from wild relatives has been shown to improve stress tolerance and yield in maize (Abdoul-Raouf et al., 2017). This genetic diversity is crucial for developing new varieties that can adapt to changing environmental conditions and meet the growing food demands (Chen et al., 2021).
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