Molecular Plant Breeding 2025, Vol.16, No.4, 231-240 http://genbreedpublisher.com/index.php/mpb 233 data, 92.4% to 95.7% of the core plant proteins were annotated. These results provide a good foundation for us to study the genetic diversity, gene family changes, and domestication-related genes of durian (Nawae et al., 2023). In addition, a research team in Hainan, China, also used RAD-seq technology to conduct genetic analysis of local durian germplasm. They also developed many SSR molecular markers, which can help breeding and gene positioning in the future (Lin et al., 2022). 3.2 Identification of major domestication-related genes Through comparative genome analysis, researchers found that in certain specific gene families (such as families related to gene regulation and protein action, especially genes related to environmental stress), durian evolved relatively quickly. These changes may have occurred during the domestication process of durian in order to adapt to the environment and improve fruit traits. In a 2023 study, Nawae et al. found that in the Monthong variety, some genes related to flowering and fruit ripening (such as methylesterase inhibition-related genes) have different expression patterns from other varieties. These genes may have a great impact on the quality and development of the fruit. The SSR molecular markers developed by Lin et al. (2022) in Hainan also provide a useful tool for finding these important genes. 3.3 Comparison of genetic diversity between wild and cultivated durian Lin’s team conducted a population structure analysis of durian germplasm in Hainan and found that 32 genotypes can be roughly divided into two main subgroups. Some of the genotypes are very similar, which shows that the existing cultivated varieties are genetically close and have a narrow genetic base. In contrast, the researchers analyzed the genomes of several major cultivated varieties in Thailand and found that there are many genetic differences between them. Differences such as copy number variation (CNV) and the presence or absence of certain genes (PAV) are particularly evident in disease resistance genes and fruit development-related genes, indicating that they have high genetic diversity (Nawae et al., 2023). 4 Selection for Fruit Quality and Sensory Traits 4.1 Evolution of key genes governing fruit aroma and flavor The special fragrance of durian mainly comes from a class of substances called “volatile sulfur compounds” (VSCs). The synthesis of these substances is related to some genes, especially genes like MGL (methionine gamma-lyase). When these genes increase in number and activity in durian, the fragrance will be more obvious. Studies have found that genes such as MGL and ethylene-related genes (such as ACS) are expressed more when durian fruits are ripe. This will also lead to the accumulation of VSCs and ethylene, resulting in the unique strong taste of durian (Teh et al., 2017). The metabolism of different durian varieties is also different. Some varieties have different contents of amino acids such as cysteine and leucine, which serve as precursors of fragrance. This change will also affect the final odor performance (Voon et al., 2007; Pinsorn et al., 2018). The differences in these metabolites and related genes provide a basis for us to select and improve the flavor of durian (Khaksar et al., 2024). 4.2 Regulation of sugar and lipid metabolism affecting taste Whether durian tastes good, sweet or soft is largely related to changes in sugars and lipids. Studies have found that when durian matures, the sucrose content increases significantly. Some oligosaccharides, such as sugars in the raffinose family, were also detected to change for the first time at this time (Sangpong et al., 2021). In addition to sugar, organic acids also play a role. For example, malic acid and succinic acid increase when ripe, but citric acid has basically not changed. These acids and changes in sugars together determine whether durian tastes sweet or sour (Voon et al., 2007). In addition, genes related to lipid metabolism are also expressed more when ripe. This also makes the flesh more fragrant and tasty (Teh et al., 2017; Vallarino et al., 2023). Through the joint study of metabolome and genome, scientists can better pick out durian varieties with high sugar, high fat and good taste (Pinsorn et al., 2018). 4.3 Selection pressure on texture-related genes The taste of durian flesh is also a point that consumers value very much. The texture is closely related to the changes in the cell wall when the fruit matures. Some “cell wall modification enzymes” play a key role in this
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