Field Crop 2025, Vol.8, No.3, 102-112 http://cropscipublisher.com/index.php/fc 105 affect the growth and development and sugar production capacity of sugarcane, but also directly threaten the commercial quality and appearance quality of sugarcane. Therefore, disease-resistant breeding is an important task for the improvement of fresh sugarcane. 3.2 Disease resistance evaluation methods Traditional disease resistance evaluation methods include natural field induction and artificial inoculation. Field induction relies on the natural occurrence of diseases. In areas with high incidence of diseases, the disease resistance level of varieties is judged by multi-point performance observations for many years. It has the advantage of strong ecological authenticity, but is greatly affected by climate and pathogen pressure fluctuations. In order to improve the screening efficiency, artificial inoculation is often combined in recent years, that is, artificially aggravating the occurrence of diseases through leaf friction inoculation, injection inoculation or spray inoculation, so as to stabilize the symptoms and facilitate the distinction between resistance and sensitivity. For example, Lu et al. (2023) supplemented artificial inoculation of mixed virus sources based on 11 natural environment points, which significantly improved the accuracy of mosaic disease resistance identification. Disease resistance scores are usually graded based on incidence, lesion area, disease grade index, etc., and are supplemented by repeated tests in multiple environments to ensure the stability and representativeness of the data. In order to reduce human errors, some studies use image analysis software to quantify the lesion area, which improves the objectivity of disease resistance evaluation. In recent years, molecular detection methods have been gradually introduced into the disease resistance diagnosis process. For example, qPCR technology can accurately quantify the content of viruses or pathogens in plants, and the ELISA method can be used for rapid screening of specific virus or fungal antigens, especially for rapid detection of pathogen-carrying status of germplasm resources in the seedling stage. These molecular-assisted methods have unique advantages in seedling disease screening and latent infection detection. 3.3 Disease resistance-related genes and genetic mechanisms At the molecular level, disease resistance is usually determined by major disease resistance genes (such as R genes) and multiple regulatory genes. Recent studies have shown that disease resistance in fresh sugarcane is a quantitative trait characterized by multi-gene co-regulation. For mosaic disease, Lu et al. (2023) combined QTL positioning and GWAS association analysis in a resistant and susceptible hybrid population to identify 7 QTLs and 9 candidate genes significantly associated with disease resistance. Most of these genes are related to plant defense signaling pathways such as PR proteins, RNA silencing, and hormone regulation, providing targets for subsequent molecular marker development and breeding. In terms of the mechanism of smut resistance, the study found that it is closely related to lignin synthesis. Li et al. (2024) identified 64 sugarcane Dirigent genes (ScDIRs), of which ScDIR5, ScDIR7, ScDIR11, and ScDIR40 were significantly induced to express under smut infection, and functional verification confirmed that they can enhance plant cell wall structure and improve defense capabilities. ScDIRs participate in the cell wall reinforcement process by regulating the accumulation of lignin precursors such as syringaresinol. In addition, Wu et al. (2023) conducted a whole genome analysis of the sugarcane CAT (catalase) gene family and found that ScCAT1 was highly expressed in smut-resistant varieties, participating in the removal of reactive oxygen species (ROS), reducing pathogen-induced oxidative stress, and improving resistance. For brown rust, the Bru1 gene is currently the most widely used major rust resistance gene, which comes from wild sugarcane. Chen et al. (2025) reported that about 86% of the newly bred rust-resistant sugarcane varieties in China carry the Bru1 gene, indicating that this gene is widely used in breeding. However, since pathogens are prone to mutation, relying on a single source of resistance may bring the risk of resistance failure. Islam et al. (2025) and Li et al. (2022) further identified multiple new rust resistance-related loci and candidate genes through SNP marker association analysis, providing new materials for the construction of multi-gene composite resistance. In terms of disease-resistant breeding technology, molecular marker-assisted selection (MAS) and CRISPR/Cas9 gene editing are becoming important tools to improve breeding efficiency. Wu et al. (2024) used the BSR-Seq
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