Bioscience Methods 2025, Vol.16, No.2, 100-107 http://bioscipublisher.com/index.php/bm 101 juvenile period, especially for breeders, who are faced with a situation where the reproductive success and fruit quality of new hybrids can be assessed over several years. The self-incompatibility of durian and not too high fruit setting rate, these reproductive obstacles also hinder breeding work, so that cross-pollination or cross-breeding attempts face many difficulties, and the success rate is difficult to reach an ideal degree. 2.2 Limited genetic diversity and breeding stocks According to the study by Lin et al in 2022, so far, the genetic basis of durian populations is limited, and most genotypes in durian populations seem to have similar genetic backgrounds, which will limit the number of new traits that can be introduced, and reduce the resistance of durians to some pests and diseases and climate change. Lin et al. (2022) developed 79,178 simple repeat sequence SSR markers in the research process, which provided help for expanding genetic resources through marker-assisted selection and quantitative trait loci positioning, and was conducive to integrating new genetic materials into the current breeding system. 2.3 Disease susceptibility and climate sensitivity Durians lack genetic diversity, have a low number of disease resistance genotypes, and are vulnerable to biological or abiotic stresses and climate change. Because of the complex interactions between durian plants and their environment, developing durian varieties that are resistant to disease and weather conditions is not straightforward. According to Lin et al. 's research in 2022, they have identified relevant genetic markers that provide useful information for improving breeding methods and making it easier to screen out durian varieties with good disease resistance and adaptability. 3 Conventional Breeding Methods and Their Limitations 3.1 Open pollination and mass selection Open pollination is natural selection, and quality selection is the selection of individuals with excellent phenotypic characteristics. Rembe et al. (2018) believe that both open pollination and quality selection have weak control over genetic diversity, leading to inbreeding and genetic drift, while Anand et al. (2023) believe that they take longer to achieve significant genetic improvement. 3.2 Hybridization techniques A 2023 study by De Vries et al. showed that hybridization is a technique that combines the best characteristics of different breeds or species to produce better offspring. The hybridization technique has remarkable effect in improving crop yield and disease resistance. Hickey et al. (2017) argued that hybridization is challenging to implement due to its complexity and resource requirements, and hybridization also requires multi-generation selection and testing to stably express desired characteristics. 3.3 Grafting and clonal propagation Grafting and clonal reproduction are techniques to maintain good individual characteristics through asexual reproduction, and have advantages in rapidly propagating good varieties, especially in cases where researchers need to maintain a specific genotype of the crop. Rembe et al. (2018) suggested that grafting and clonal reproduction may reduce genetic diversity, and they are less adaptive to environmental changes. 4 Genomic Advances in Durian Breeding 4.1 Durian genome sequencing and its implications Complete genome sequences can be used by researchers to identify specific genomic regions, genes, and alleles associated with desirable traits. Key traits such as fruit quality, disease resistance and environmental adaptability were proposed by Xu et al. (2012) and Salgotra and Stewart (2020). This genetic information facilitates the development of molecular markers for use in breeding programs to improve important traits. Durian genome sequencing facilitated the construction of high-density genetic maps, which helped to identify quantitative trait loci associated with key agronomic traits. 4.2 Marker-assisted selection (MAS) for trait improvement The researchers used marker-assisted selection to select durians with good traits at an early stage. Tiwari et al.
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