Rice Genomics and Genetics 2024, Vol.15, No.2, 58-68 http://cropscipublisher.com/index.php/rgg 65 5 Application of Wild Rice Germplasm Resources in Rice Breeding 5.1 Utilizing wild rice genes to improve the stress resistance of cultivated rice Wild rice has many excellent traits that can be utilized in rice breeding. According to IRRI's research, the opportunity to search for resistance genes from wild rice is more than 50 times higher than from cultivated rice. Wild rice has strong insect resistance, is an excellent antigen for rice diseases and pests, and also has good stress resistance. The common wild rice in Dongxiang, Jiangxi, China is located at 24N° in January with an average temperature of 5.2 °C and a minimum temperature of -8 °C-5 °C can also safely survive the winter (Tiwari and Yadav, 2020). There are materials with excellent quality in wild rice, mainly manifested as white belly, glassy texture, non easily broken rice grains, and high protein and lysine content. In medicinal wild rice, some materials not only have good appearance quality but also high protein content, up to 16%, making them good materials for high-quality breeding. At the same time, medicinal wild rice has high medicinal value. Wild rice also has strong growth advantages, and its distant hybridization with cultivated rice has great potential for cultivating varieties with strong growth advantages. Especially, ordinary wild rice has fertility restoration genes, and its chromosomes are both AA type and have good affinity with cultivated rice. It has been widely used in the breeding of hybrid rice three lines. Wild rice also has strong regeneration ability, and many materials in China's perennial common wild rice have particularly strong regeneration ability. Wild rice has evolved over a long period of time in the natural environment, forming resistance to various stresses. Among them, traits such as drought resistance, salt alkali resistance, and disease and pest resistance have been fully demonstrated in wild rice. Through in-depth research on the genome of wild rice, scientists can discover and understand the genetic mechanisms behind these stress resistance traits, including the localization and functional analysis of key genes. For example, researchers analyzed lncRNAs in rice using multiple recombination methods and found that compared to their ancestor species, common wild rice, 95% of lncRNAs in Asian cultivated rice were downregulated, and the downregulated lncRNAs exhibited population genetic characteristics consistent with the genome segments subjected to targeted selection during evolution. The target genes of these differentially expressed lncRNAs are enriched at sites related to carbon fixation ability and carbohydrate metabolism. Through experiments, it was verified that the decrease in expression levels of three lncRNAs directly leads to an increase in starch content and grain weight in rice seeds, revealing the multi-level regulatory mechanism of rice yield and quality. The downstream expression effects of these lncRNAs have a significant impact on various rice traits, and these effects may have been selected during the domestication process of japonica rice (Figure 2) (Zheng et al., 2019). Figure 2 A model for the evolution of lncRNAs during rice domestication (Adopted from Zheng et al., 2019)
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