Molecular Pathogens, 2025, Vol.16, No.3, 134-146 http://microbescipublisher.com/index.php/mp 142 of hundreds of varieties (lines) to show high resistance to medium resistance (Thushari et al., 2021). In terms of brown rust resistance, Australia and other countries have discovered and utilized the Bru1 main effect rust resistance gene. The Chinese scientific research team tested 94 new sugarcane varieties and main planted varieties, and found that 54 of them were rust-resistant varieties carrying the Bru1 disease-resistant gene. These rust-resistant resources have been widely used in hybrid breeding, effectively improving the resistance level of new varieties to rust. For pests such as borers, sugarcane lacks absolutely insect-resistant varieties, but the tolerance of different varieties is still different. Some varieties with high stem hardness and high fiber content are not conducive to borer larvae and can be used as parental materials for borer resistant breeding. In addition, there is a rich refractory gene pool in wild sugarcane relatives (Sakaigaichi et al., 2018). In the history of "noble" breeding of sugarcane, wild species' disease-resistant genes have been introduced into cultivated species many times through distant hybridization. Today, breeders continue to discover wild resources, such as resistance to sugarcane thrips found in the Aroma plant near sugarcane. Basic research on resistance genetics also provides breeding molecular targets. Using transcriptome sequencing and QTL localization techniques, scientists identified multiple genes and markers related to sugarcane borer resistance. These findings laid the foundation for in-depth analysis of sugarcane insect resistance mechanisms and cultivating high-resistant varieties. 7.2 Progress in application of molecular marker assisted breeding The traditional breeding cycle of sugarcane is more than 10 years, and the application of technologies such as molecular marker-assisted selection (MAS) can accelerate the breeding process of disease-resistant varieties. In recent years, researchers have developed molecular markers for several important resistance genes in sugar cane. In response to the Bru1 gene for sugarcane brown rust resistance, the tight linkage markers R12H16 and 9O20-F4 were developed as early as 2008, and have been used for anti-rust premature screening in sugarcane breeding families. In response to sugarcane orange rust resistance, G1 molecular marker was reported in 2018, which can assist in the identification of materials carrying orange rust-resistant genes. Through RAPD, SSR and other technologies, the Chinese scientific research team has successively identified molecular markers related to sugarcane smut resistance and SSR markers related to leaf blight resistance (Gao, 2013). The application of these markers makes it possible to screen out potential disease-resistant materials during the seedling stage without waiting for the later phase of field inoculation identification, thereby significantly improving breeding efficiency. In addition to marker-assisted selection, modern molecular breeding has also introduced new methods such as genome-wide selection (GS), that is, using a large number of markers across the genome-wide range to predict the selection of target traits. In the improvement of sugarcane complex traits (such as yield, comprehensive stress resistance), GS is expected to make up for the limitations of traditional single-gene marker selection. At the same time, with the breakthrough in sugarcane genome sequencing and gene editing technology, it has become possible to targeted cultivation of new pest-resistant sugarcane varieties. Some people have used CRISPR/Cas9 technology to knock out homologous genes that are susceptible to rust in sugarcane and obtain rust-resistant sugarcane materials; there are also research to create transgenic sugarcane systems that are resistant to borer by transferring the Bt toxic protein gene. Brazil officially approved the cultivation of the world's first commercial genetically modified borer-resistant sugarcane variety in 2017, providing a new direction for sugarcane insect-resistant breeding. 7.3 Problems and solutions in promotion The selection and breeding of disease-resistant sugarcane varieties is only the first step, and it still faces many challenges in promoting and applying them on a large scale. Issue of farmers' acceptance of new varieties. Some pest-resistant varieties may be slightly inferior to traditional high-quality varieties in terms of yield or sugar content, and farmers are often reluctant to change varieties due to the consideration of short-term yield. This causes some high-sensitivity products (such as ROC22, which has been promoted for more than 20 years) to be planted on a large scale, resulting in serious accumulation of pests and diseases and slow promotion of new varieties (Memon et al., 2021). In response to this situation, on the one hand, it is necessary to strengthen demonstration and publicity to let farmers realize the hidden losses caused by long-term congested varieties (such as the epidemic of smut disease caused a significant reduction in yield of perineal roots, etc.), and to increase their
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