International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.6, 294-302 http://ecoevopublisher.com/index.php/ijmec 298 Figure 2 The impact of the canker disease on the pitaya stems and fruits (Adopted from Xu et al., 2019) Image caption: a Diseased stems in pitaya plantation; b Diseased fruits in pitaya plantation (Adopted from Xu et al., 2019) 5.2 Exploration and utilization of disease-resistant germplasm Based on the results of systematic screening, some wild and local yellow pitaya materials show strong disease resistance, especially stable resistance to canker. Such germplasms generally have high defense enzyme activities, such as peroxidase, catalase and polyphenol oxidase. At the same time, the application of biological control agents such as Bacillus siameensis and endophytic fungi can induce plants to activate defense mechanisms and play an important role in maintaining ROS homeostasis (Taba et al., 2021; Wang et al., 2021; Xu et al., 2024). Directed hybridization combined with backcross breeding provides an effective way to introduce disease resistance traits into superior varieties. Molecular marker-assisted selection (MAS) combined with transcriptome analysis technology can accurately track the genetic laws and expression regulation of resistance genes, significantly improving breeding efficiency (Shah et al., 2023). 5.3 Application of molecular breeding and genetic engineering Functional genomics studies have shown that gene families such as PR, WRKY and LRR play a core role in the disease resistance of yellow pitaya (Xu et al., 2019). Whether it is conventional hybridization or genetic engineering technology, regulating the expression levels of these key genes can enhance the disease resistance of plants. The application of CRISPR/Cas9 system in yellow pitaya is still in the optimization stage, but the analysis of susceptible genes (S genes) and their regulatory networks has provided key targets for gene editing breeding (Wang et al., 2024b). By targeted modification of the S gene and activation of defense-related genes, it is expected to systematically improve the resistance of yellow pitaya to fungal and viral diseases. 6 Integration of Breeding and Cultivation Technologies 6.1 Construction of integrated molecular and phenotypic screening systems The fusion of high-throughput phenomics and molecular marker technologies such as SNP and SSR has built an efficient platform for rapid screening of important traits of yellow pitaya. Relying on in vitro propagation technologies such as cell culture and tissue culture, the evaluation cycle of germplasm resources has been greatly reduced. The establishment of a molecular marker-assisted selection system has taken breeding efficiency to a new level. Integrating transcriptome and metabolome data to decipher the genetic regulatory network of yield, quality and stress resistance traits has injected multi-dimensional theoretical momentum into precision breeding practices (Huang et al., 2022; Shah et al., 2023). Omics research has revealed the interaction mechanism between light conditions and plant metabolic pathways, providing scientific guidance for optimizing the growth environment and improving target traits (Huang et al., 2022). 6.2 Matching breeding with facility and environmental control To cultivate yellow pitaya varieties suitable for diversified cultivation systems (open field/greenhouse), adverse factors such as high temperature, drought, and strong light are unavoidable considerations (Al-Qthanin et al., 2023). Studies have shown that with scientific fertilizer and water management and environmental regulation,
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