TGMB_2024v14n6

Tree Genetics and Molecular Breeding 2024, Vol.14, No.6, 295-303 http://genbreedpublisher.com/index.php/tgmb 297 genetic base that can be exploited to select for larger and heavier fruits (Cockerton et al., 2023). This genetic variability is essential for developing new cultivars with enhanced fruit size and weight, which are key determinants of market value and consumer preference. Flowering time and pollination success are critical components of yield in dragon fruit, as they directly affect fruit set and overall productivity. Genetic studies have shown that these traits are influenced by both genetic and environmental factors. The genetic diversity observed in dragon fruit populations, as indicated by high heterozygosity and polymorphic loci, suggests that there is potential for selecting genotypes with optimal flowering times and improved pollination success (Maan et al., 2023). This diversity allows for the identification of genetic markers associated with these traits, facilitating the development of varieties that can thrive in different environmental conditions and have higher yield potential. 3.2 Significant markers associated with yield Significant genetic markers associated with yield traits in dragon fruit have been identified through the use of ISSR markers, which have proven effective in distinguishing between high-yielding and low-yielding genotypes. In particular, studies have highlighted the utility of specific ISSR primers, such as UBC824, UBC891, and UBC900, in fingerprinting genotypes with desirable yield characteristics (Lopez-Nieves et al., 2018; Forcada et al., 2019). These markers provide a valuable tool for breeders to select and propagate dragon fruit varieties with superior yield traits, thereby enhancing productivity and meeting market demands. The identification of these markers is a crucial step in the development of targeted breeding strategies aimed at improving yield and quality traits in dragon fruit. 4 Quality Traits in Dragon Fruit 4.1 Genetic basis of quality-related traits The sugar content and acidity in dragon fruit are critical quality traits that significantly influence consumer preference and market value. These traits are largely determined by the genetic makeup of the fruit, which varies widely among different genotypes. Studies have shown that the genetic diversity within dragon fruit species, such as Selenicereus megalanthus, is substantial, with a high level of heterozygosity and polymorphic loci, indicating a broad genetic base that can be exploited for breeding programs aimed at enhancing these quality traits (Morillo et al., 2022). The genetic parameters, such as expected average heterozygosity and genetic distances, provide insights into the potential for selecting genotypes with optimal sugar content and acidity levels (Kenis et al., 2008; Khan et al., 2024). Pigmentation and antioxidant properties are other essential quality traits in dragon fruit, contributing to its nutritional value and appeal. The pigmentation, primarily due to betalains, and the antioxidant capacity are influenced by the genetic diversity present in the fruit. Research utilizing ISSR markers has revealed significant genetic variation among dragon fruit accessions, which correlates with differences in pigmentation and antioxidant levels (Figure 1) (Forcada et al., 2019; Chen et al., 2021; Zheng et al., 2021). This genetic diversity is crucial for breeding programs focused on enhancing these traits, as it allows for the selection of genotypes with superior pigmentation and antioxidant properties, thereby improving the fruit's health benefits and marketability (Fernández-López et al., 2020; Lin et al., 2024). 4.2 Significant markers associated with quality Significant genetic markers associated with quality traits in dragon fruit have been identified through various molecular techniques, such as ISSR markers. These markers are instrumental in distinguishing between different genotypes and understanding the genetic basis of quality traits. For instance, the use of ISSR markers has enabled the identification of polymorphic bands that are associated with specific quality traits, such as sugar content, acidity, pigmentation, and antioxidant properties (Capel et al., 2015; Zhao et al., 2024). The high percentage of polymorphic bands and the polymorphism information content (PIC) values indicate a rich genetic diversity that can be harnessed to improve quality traits through targeted breeding strategies (Forcada et al., 2019; Tel-Zur et al., 2022). This genetic information is vital for developing dragon fruit varieties with enhanced quality traits, meeting consumer demands, and increasing the fruit's economic value.

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