Molecular Plant Breeding 2025, Vol.16, No.3, 191-201 http://genbreedpublisher.com/index.php/mpb 192 Recently, modern gene editing technologies represented by the CRISPR/Cas9 system have demonstrated unique advantages, providing a new pathway for genetic improvement of fruit quality. By precisely regulating ripening related genes, fruit hardness can be enhanced, ripening can be delayed, and shelf life can be extended (López Casado et al., 2023). CRISPR/Cas9 can enhance fruit firmness, improve post harvest disease resistance, and achieve the dual goals of extending shelf life and improving overall fruit quality by silencing or modifying key genes such as polygalacturonase and pectin lyase (Yang et al., 2017; López Casado et al., 2023). This study will explore the use of genome editing to regulate the softening process of durian peel, with a focus on analyzing relevant molecular pathways and genetic regulatory networks, and identifying potential genetic modification targets. Utilizing technological innovation to extend the commercial shelf life of durian and reduce post harvest losses can not only provide theoretical basis for the application of gene editing technology in improving the quality of tropical fruits, but also help cultivate new varieties with higher market adaptability and promote the sustainable development of the durian industry. 2 Phenotypic and Molecular Characteristics of Durian Fruit 2.1 Phenotypic identification of gene-edited durian fruit Durian is a typical climacteric fruit, and its ripening process is accompanied by a sharp increase in ethylene and a peak in respiration. Shortly after harvesting, the durian peel begins to soften and its hardness decreases rapidly. The study compared the softening rates of different durian varieties: Monthong and Kanyao are slow-ripening varieties, and the peel softens about 5 days after harvesting; while fast-ripening varieties such as Chanee and Phuangmanee reach edible maturity 3 days after harvesting (Khaksar et al., 2019; Khaksar and Sirikantaramas, 2020). Instrumental measurement of the texture of the peel showed that the peel of durian was still hard one day after harvesting, and the hardness value in the texture profile analysis decreased sharply as it matured. In the report of Khaksar and Sirikantaramas (2020), the hardness of durian pulp dropped from about 3.4 N in the unripe stage to 1.55 N in the fully ripe stage, confirming the occurrence of significant softening of the peel and pulp. Peel softening directly determines the shelf life and storage characteristics of durian: the softer the peel, the harder it is for the fruit to withstand handling vibrations, and it is very easy to crack or rot, limiting long-distance transportation and long-term storage. Therefore, phenotypic measurement of durian postharvest softening characteristics by the rate of peel hardness reduction and shelf life is very important for screening storage-resistant varieties and evaluating improvement effects. 2.2 Molecular characterization analysis of gene-edited durian The softening process of durian is precisely regulated by a series of genes related to cell wall degradation and hormone signals. To perform genome editing on these genes, their sequences and functions must first be clarified. Durian whole genome sequencing and transcriptome analysis provide a basis for this: the draft durian genome published in 2017 identified a large number of candidate genes related to fruit ripening. For example, polygalacturonase (Pg, encoding pectinase PG) and cellulase (Cel) genes are highly expressed during durian ripening and are believed to be responsible for decomposing cell wall polysaccharides in the peel and pulp, resulting in softening texture (Pan et al., 2022). The β-galactosidase (BGal) gene increases the porosity of the cell wall by removing the galactosyl group of the pectin side chain of the cell wall, accelerating the action of other enzymes on the cell wall. In addition, there are also multiple ethylene biosynthesis-related genes in the durian genome, such as 1-aminocyclopropane-1-carboxylic acid synthase ACS2 and oxidase ACO1; these genes directly determine the ethylene production rate and are key switches for regulating the ripening process. For example, the MaACO1 homologous gene found in banana is also highly conserved in durian, and its knockout or functional loss is expected to significantly reduce ethylene release and delay ripening (Hu et al., 2021). 3 Molecular Mechanisms of Durian Pericarp Softening 3.1 Physiological and biochemical processes of pericarp softening Durian peel softening is a complex physiological and biochemical process driven by a multi-level regulatory network, including cell wall degradation, hormone signals, and metabolic changes. From a physiological point of view, fruit softening mainly stems from the disintegration of cell wall structure and the increase of cell membrane
RkJQdWJsaXNoZXIy MjQ4ODYzNA==