Molecular Pathogens, 2025, Vol.16, No.2, 45-52 http://microbescipublisher.com/index.php/mp 47 3.2 Bacterial leaf streak (Xanthomonas oryzae pv. oryzicola) 3.2.1 Genetic loci associated with resistance Bacterial stripe disease (BLS for short) is caused by the leukoplakia (Xoc) and is another common disease in rice (Figure 1). Current research has found several gene loci related to disease resistance. These sites are important for breeding efforts because they can help rice fight bacteria. These genes and substances released by bacteria will react, just like the Xa gene used in white leaf blight, which can enable rice to activate its own defense mechanism and thus play a role in anti-disease (Jiang et al., 2020). 3.2.2 Breeding challenges and advances Although we have achieved some results in researching anti-BLS, there are still many difficulties in the breeding process. One of the biggest challenges is that the bacteria change too quickly, and the pathogenesis of rice is quite complicated. Fortunately, molecular breeding technology has developed rapidly in recent years, and technologies such as genome-wide association analysis have helped us find some new disease-resistant genes. These methods also allow us to breed BLS-resistant rice varieties faster. This is very critical to controlling the disease. Figure 1 Symptoms of (a) bacterial light caused by Xanthomonas oryzae pv. oryzae and (b) bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola(Adopted from Jiang et al., 2020) 3.3 Other emerging bacterial diseases and their impact In addition to white leaf blight and stripe spot disease, some new bacterial diseases have also appeared on rice in recent years. These diseases also pose new threats to yield. To solve these problems, we have to continue to do research and continue to carry out breeding. Finding new disease-resistant genes and using them in breeding is the key to controlling these new diseases. Now, people are also using modern methods such as genetic engineering and marker-assisted selection. These new technologies can improve the efficiency of disease-resistant breeding and can also help us better deal with these new bacterial diseases (Chukwu et al., 2019; Liu et al., 2021; Matsumoto et al., 2021). 4 Molecular and Genomic Approaches in Disease-Resistant Rice Breeding 4.1 Application of CRISPR and genome editing in resistance enhancement TThe emergence of CRISPR and other gene editing technologies has given new ways to resist disease breeding in rice. In particular, CRISPR/Cas9 technology can directly change some genes that make rice prone to disease, which is the so-called "susceptible gene" (S gene), thereby enhancing the disease resistance of rice. For example, after the S genes such as Pi21, Bsr-d1 and Xa5 are changed, rice has become more resistant to pathogens such as rice blast bacteria and white leaf blight bacteria, and the normal growth of rice is not affected (Mishra et al., 2021; Tao et al., 2021). This technology can also modify multiple genes at once, helping to breed rice varieties that are resistant to multiple diseases. 4.2 Identification and mapping of quantitative trait loci (QTLs) To figure out how rice has the disease resistance, it is very important to find QTL related to disease resistance.
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