Rice Genomics and Genetics 2024, Vol.15, No.3, 106-120 http://cropscipublisher.com/index.php/rgg 111 5 Genetic Diversity and Its Utilization 5.1 Assessing genetic diversity inOryza The assessment of genetic diversity in Oryza species has been significantly advanced by the development of various genomic tools and techniques. High-throughput sequencing technologies, such as RADSeq and SLAF-seq, have enabled the detailed analysis of genetic variation across different Oryza species. For instance, RADSeq was used to assess the genetic diversity of Oryza longistaminata in Ethiopia, revealing high genetic diversity and regional differentiation (Melaku et al., 2019). Similarly, SLAF-seq facilitated the development of a genome-wide SNP array for Oryza rufipogon, which was used to genotype 110 accessions and assess their genetic structure (Zhang et al., 2020). Advances in DNA sequencing technologies have also led to the creation of platinum standard reference genome sequences (PSRefSeq) for all Oryza species, setting a new benchmark for integrating wild relatives into crop improvement programs (Mussurova et al., 2020). Moreover, Techniques like genome-wide association studies (GWAS) and quantitative trait locus (QTL) mapping have proven invaluable in uncovering the genetic basis of traits such as disease resistance, yield, and stress tolerance. Several case studies highlight the genetic diversity present in wild and cultivated Oryza species. For example, Melaku et al. (2019) studied the genetic diversity and regional differentiation of African wild rice (Oryza longistaminata) in Ethiopia. Using SSR markers on 360 samples and RADSeq analysis on 87 early-maturing samples, they found high genetic diversity (PIC=76.5%) and regional genetic differentiation (Fst=0.08) in the wild rice populations (Figure 2). The results indicate that genetic relationships among these populations are primarily based on their geographic origins. The high genetic diversity and regional differentiation suggest that these wild rice populations are valuable genetic resources for rice improvement projects (Melaku et al., 2019). Another study on Oryza rufipogon in Guangdong Province, China, used a 79,422-SNP array to reveal significant genetic differentiation among accessions from different agroclimatic zones (Zhang et al., 2020). Additionally, the genetic diversity of African rice (Oryza glaberrima) has been explored through whole genome re-sequencing, providing insights into its domestication process and potential for breeding climate-resilient rice varieties (Wambugu et al., 2019). 5.2 Conservation of genetic resources The conservation of genetic resources in Oryza species is crucial for maintaining their genetic diversity and potential for crop improvement. In-situ conservation involves preserving wild rice populations in their natural habitats, which helps maintain their ecological interactions and evolutionary processes. Ex-situ conservation, on the other hand, involves the collection and storage of genetic material in germplasm banks and repositories. For instance, the genetic diversity of Oryza rufipogon, an endangered species due to habitat loss, has been assessed to inform conservation strategies. The establishment of chromosome segment substitution lines (CSSLs) from wild rice species also contributes to ex-situ conservation by preserving valuable genetic traits for future breeding programs (Yuan et al., 2020). Germplasm banks and repositories play a vital role in the conservation and utilization of genetic resources from wild and cultivated Oryza species. These facilities store genetic material, such as seeds and DNA samples, which can be used for breeding and research purposes. For example, Zhang et al. (2022) developed an introgression library of agronomic traits from all AA genome Oryza species, providing a valuable resource for rice improvement. The construction of Oryza pan-genomes, which include high-quality genome assemblies from both cultivated and wild rice populations, further enhances the accessibility and utilization of genetic diversity for future rice research and improvement (Huang et al., 2021). The assessment and conservation of genetic diversity in Oryza species are essential for the sustainable improvement of rice. Advances in genomic tools and techniques, along with effective conservation strategies, provide a strong foundation for utilizing the genetic resources of wild and cultivated Oryza species in rice breeding programs.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==