Tree Genetics and Molecular Breeding 2025, Vol.15, No.1, 18-24 http://genbreedpublisher.com/index.php/tgmb 19 2021; Nazir et al., 2024). Hu et al. (2022) found that the growth environment of some wild kiwifruit species in China has been damaged and they are facing survival threats. Protecting these wild resources has become very urgent. Oh et al. (2018) indicated that kiwifruit germplasm resources from different countries and regions can provide a lot of useful genetic materials for breeding, which is beneficial for improving existing varieties, enhancing the stress resistance of kiwifruit and ensuring its sustainable development. 2.3 Key traits contributed by genetic diversity Oh et al. (2016) held that the traits in the genetic diversity of kiwifruit are useful for its resistance to pests and diseases, improvement of fruit quality, and enhancement of its adaptability to the environment. The genetic differences between wild kiwifruit and artificially cultivated kiwifruit can be used to breed new species that are more resistant to diseases. Li et al. (2014) and Nazir et al. (2024) found that breeding efforts pay much attention to these aspects, hoping to make new varieties more popular among consumers and meet market demands. Wang et al. (2022) demonstrated that advanced genetic technologies such as SNP genotyping and marker-assisted selection can identify useful traits more quickly and introduce them into new varieties, making breeding faster and more accurate. 3 Advances in Kiwifruit Breeding Techniques 3.1 Traditional breeding approaches Traditional breeding methods select well-performing individuals from naturally growing populations or combine ideal traits through hybridization between different species, which play a key role in improving fruit quality and disease resistance (Li et al., 2014; Nazir et al., 2024). The genus Actinidia has a rich genetic diversity, providing many options for breeding work. Breeders can select suitable parents based on different traits. Ferguson’s (2007) early research found that traditional breeding has a long cycle and high investment, and it takes several generations to see stable improvement effects. 3.2 Modern breeding tools and techniques The studies of Zhang et al. (2015) and Nazir et al. (2024) demonstrated that MAS can recognize and screen molecular markers related to specific traits, which is beneficial for rapidly identifying individuals with ideal genes in plants and improving breeding efficiency. Pinheiro et al. (2020) also found that it can accurately select gender-related individuals and reduce the uncertainty in the breeding process, solving the problem of dioecious kiwifruit. Genomic selection (GS) is to use the information of the entire genome to predict the breeding value of plants (Li et al., 2024). It is suitable for selecting relatively complex traits such as fruit quality and yield. The application of GS in kiwifruit has become more feasible because there is now a reference genome of Actinidia chinensis. However, kiwifruit breeding materials have the characteristics of polyploidy and high heterozygosity, which bring some technical difficulties to practical operations. 3.3 CRISPR-Cas9 and genome editing applications The recent study by Nazir et al. (2024) demonstrated that the CRISPR-Cas9 gene editing technology can precisely modify the genome directly, eliminating undesirable traits or enhancing the desired favorable ones. It can assist researchers in cultivating new varieties with stronger disease resistance and better fruit quality more quickly. Li et al. (2022) demonstrated that CRISPR-Cas9 has great potential in kiwifruit breeding and may make up for the deficiencies of traditional breeding and molecular marker-assisted breeding. 4 Utilizing Wild Relatives in Kiwifruit Breeding 4.1 Unique traits from wild kiwifruit species Wild kiwifruit species such as Actinidia eriantha and Actinidia kolomikta have abundant genetic resources. Wild species have some characteristics that cultivated varieties do not possess. They have stronger disease resistance or their fruits have a unique flavor. Cheng et al. (2019) found that the flower-shaped kiwifruit can resist the common canker disease in kiwifruit, and its fruit has a special taste, which has received much attention in breeding. Liao et
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