Rice Genomics and Genetics 2025, Vol.16, No.2, 96-105 http://cropscipublisher.com/index.php/rgg 101 Figure 2 Mitochondrial genome nucleotide diversity (pi) and genetic distance (Fst) (Adopted from Tong et al., 2017) Image caption: (a-c) pi of the whole collection; landrace and weedy rice; wild and the others (landrace and weedy rice). (d) The pi of indica, japonica, O. nivara and O. rufipogon. Values are sorted by ascending. (e) The average pi of indica and japonica in landrace or weedy rice. (f, g) The Fst between different groups. The circles indicated different groups and the circle size indicated the pi value. The Fst value between each two groups were represented by the distance between them. L: landrace rice, W: weedy rice, Wild: wild rice. LI: landrace_indica, WI: weedy_indica, LJ: landrace_japonica, WJ: weedy_japonica, NIV: O. nivara, RUF: O. rufipogon (Adopted from Tong et al., 2017) 6.3 Strategies for reintroducing genetic variation Scientists have proposed several strategies to compensate for the loss of genetic diversity caused by domestication. For example, wild relatives with rich genetic diversity, such as O. rufipogon and O. nivara, are used as a source of new genes (Zhu et al., 2007). In addition, variation and emerging mutations in weedy rice are also seen as potentially valuable resources (Qiu et al., 2017). Modern methods such as genome-wide association studies (GWAS) help locate and introduce gene regions associated with desirable traits, promoting the introduction of genes from traditional and wild varieties into modern varieties (McNally et al., 2009). The goal of these practices is to enhance rice stress resistance and yield, and to tap the potential of wild and traditional genetic resources。 7 Case Study: Evolution and Domestication of Cultivated Rice 7.1 Historical background of domestication of cultivated rice As one of the world's major food crops, the domestication history of cultivated rice (Oryza sativa) has always been a focus of debate among researchers. In fact, cultivated rice is not the result of a single domestication. Studies have shown that its origin is closely related to its wild ancestor Oryza rufipogon, but this process may have undergone multiple independent domestications. For example, the two main rice species, indica rice and japonica rice, were domesticated from different wild populations. It is generally believed that indica rice was formed in the area south of the Himalayas, such as eastern India, Myanmar, Thailand, etc., while the origin of
RkJQdWJsaXNoZXIy MjQ4ODYzNA==