Molecular Plant Breeding 2025, Vol.16, No.3, 202-210 http://genbreedpublisher.com/index.php/mpb 203 CRISPR/Cas9 has been widely used in plant functional gene research and crop breeding improvement due to its simplicity, high efficiency and strong specificity (Karkute et al., 2017; Ma et al., 2023). Since the first report of plant gene editing in 2013, many fruit trees and vegetable crops have successfully achieved knockout or precise mutation of target genes. In particular, CRISPR technology has shown great potential in improving fruit quality, including a series of breakthroughs such as increasing the sugar content of tomatoes, reducing the acidity of citrus, and optimizing the aroma substances of strawberries (Fan et al., 2022; Ma et al., 2023). This study will focus on the formation mechanism and key metabolic pathways of the flavor of golden pitaya, explore genes that can be used as targets for flavor improvement, and summarize the strategies and research progress of CRISPR/Cas9 technology in improving fruit flavor. At the same time, the technical bottlenecks that may be encountered in carrying out gene editing in golden pitaya are analyzed and coping strategies are proposed, in order to provide a theoretical basis and technical support for the targeted improvement of tropical fruit quality, thereby achieving precise breeding of golden pitaya flavor and enhancing industrial value. 2 Analysis of Flavor Components and Metabolic Pathways of Golden Pitaya 2.1 Composition of flavor-related metabolites The pitaya fruit is round or oval, and the peel color is red (H. polyrhizus, H. undatus), green (H. stenopterus) and yellow (H. megalanthus, Selenicereus megalanthus) (Figure 1) (Shah et al., 2023). Bird’s nest fruit is a golden pitaya, and its flavor components are mainly composed of sugars, organic acids and volatile aromatic substances. The soluble sugars in its pulp are mainly glucose and fructose, and the sweetness is more prominent than that of red or white pitaya. The soluble solids content (TSS) is generally 12~15 Brix, and some high-quality strains even reach 20 Brix (Valero et al., 2025). The sour taste of bird's nest fruit mainly comes from malic acid, citric acid and a more special citric maleic acid (Citramalic acid), the latter of which accounts for 7.56%~71.42% in different strains (Wu et al., 2020). During the fruit ripening process, sugar gradually accumulates and organic acid decreases, which increases the sugar-acid ratio and makes the flavor tend to be sweet and balanced. Figure 1 Fruit peel, pulp, and scale and areoles phenotype found in different Hylocereus species (Adopted from Shah et al., 2023) Image caption: (A) H. undatus; (B) H. polyrhizus; (C, D) hybridization offspring of H. polyrhizus and H. undatus; (E) H. megalanthus; (F) Golden pitaya (yellow clone of H. undatus), (G) H. stenopterus (Adopted from Shah et al., 2023)
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