Rice Genomics and Genetics 2024, Vol.15, No.6, 309-319 http://cropscipublisher.com/index.php/rgg 312 4.2 Role in modern breeding programs Wild rice varieties play a crucial role in modern breeding programs by broadening the genetic base of cultivated rice. Techniques such as wild hybridization and gene introgression are employed to introduce beneficial alleles from wild species into cultivated varieties, thereby enhancing traits like pest resistance and tolerance to abiotic stress. The integration of genomic resources from wild rice relatives has facilitated the identification and characterization of novel beneficial alleles, which are essential for developing high-yield, stress-tolerant rice varieties (Figure 2). Moreover, the utilization of natural genetic variation, as seen in the GSE5 gene, has significantly contributed to the improvement of important agronomic traits such as grain size (Duan et al., 2017). Figure 2 Diversity of wild rice species. The 24 wild Oryza species are divided into a primary gene pool (Oryza sativa complex, AA genome), a secondary gene pool (Oryza officinalis complex, BB to EE genomes), and a tertiary gene pool (O. meyeriana complex and unclassified species, FF to KKLL genomes). Images are taken by the authors at the International Rice Research Institute (IRRI) (Adopted from Solis et al., 2020) 4.3 Challenges in utilizing wild varieties Despite their potential, the utilization of wild rice varieties in breeding programs faces several challenges. One major issue is the agronomic inferiority of wild species, which makes them less desirable for direct cultivation (Kamboj et al., 2020). Additionally, the unavailability of comprehensive genetic and genomic resources for wild rice species has historically hindered the identification and characterization of beneficial alleles. Another challenge is the complexity of integrating wild traits into cultivated varieties without compromising other desirable characteristics. For example, while wild varieties may offer disease resistance, they may also introduce undesirable traits that need to be carefully managed through advanced breeding techniques. Furthermore, the labor-intensive and time-consuming nature of conventional breeding methods poses a significant barrier to the efficient utilization of wild rice varieties (Li, 2020).
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