Molecular Plant Breeding 2025, Vol.16, No.5, 287-293 http://genbreedpublisher.com/index.php/mpb 289 the improvement of ornamental traits. Molecular markers have also been used to assist in germplasm identification and management, improving the recognition efficiency of superior genotypes and reducing resource duplication and homonymous foreign substances. 3.2 Hybridization attempts and limitations Some progress has been made in hybrid breeding in the improvement of ornamental traits. Through artificial pollination and planned parent selection, a variety of new and superior varieties with stable leaf color and morphology have been obtained, some of which have performed outstandingly in garden and bonsai applications (Ming, 2001). However, the generation cycle of Ginkgo biloba is very long, the hybridization fruiting rate is low, and the trait segregation of offspring is large, resulting in an overly long hybridization breeding cycle, low efficiency, and difficulty in rapidly aggregating the target trait (Han et al., 2023). 3.3 Vegetative propagation and clonal selection for trait stabilization Ginkgo biloba is propagated asexually through methods such as grafting and cuttings to avoid the separation of traits caused by sexual reproduction. Ming’s (2001) early research found that these techniques could achieve rapid propagation of superior individual plants and maintain the stability of traits. Clonal selection and breeding can ensure the consistency of medicinal components and ornamental traits, and also facilitate large-scale promotion. Han et al. (2023) found that in recent years, molecular biology and cell engineering techniques have provided new tools for the study of Ginkgo biloba gene functions and the optimization of asexual reproduction systems, which are expected to further enhance the stability of superior traits and the efficiency of genetic improvement. 4 Molecular and Genomic Breeding Strategies 4.1 Development of molecular markers (SSR, SNP, AFLP) for trait mapping Researchers have developed a large number of markers such as SSR, SNP and InDel by using transcriptome and genomic data. Based on the studies of EST-SSR and InDel, it was found that the Ginkgo biloba germplasm resources have a high genetic diversity, and a core germplasm bank was successfully established. These achievements provide basic tools for trait mapping and genetic improvement (Wang et al., 2023; Yao et al., 2023). Wu et al. ’s research in 2019 demonstrated that the development of SNP markers and the application of high-resolution melting curve technology have also enhanced the efficiency of genetic diversity analysis and functional gene mining in Ginkgo biloba populations. These molecular markers have been widely used in fingerprint mapping construction, germplasm identification, genetic diversity evaluation and core germplasm screening. 4.2 Genomic insights: transcriptomics, genome sequencing, and gene mining Han et al. (2023) demonstrated that the draft whole genome and high-quality genome of Ginkgo biloba have been released, providing a scientific basis for the mining of functional genes and the study of complex traits. Transcriptome sequencing revealed the key genes and their regulatory networks related to the synthesis of important secondary metabolites such as flavonoids and lignin (Wu et al., 2018). Some transcription factors have been systematically identified and expression analyzed, providing target genes for increasing the content of medicinal components and improving stress resistance (Zhou et al., 2020). Genome-wide gene family studies have expanded the molecular understanding of Ginkgo biloba growth and development and stress response (Guo et al., 2023; Li et al., 2024). 4.3 Marker-assisted selection (MAS) and genomic selection prospects By combining molecular markers and phenotypic data, target traits (such as medicinal component content, leaf color, stress resistance, etc.) can be screened more efficiently, and selection can be made at an early stage. Ginkgo biloba has a long life cycle and a complex genetic background. However, both MAS and genomic selection (GS) have shown great potential in core germplasm construction, aggregation of superior genotypes, and conservation of genetic diversity (Wang et al., 2023; Yao et al., 2023). With the increase in the number and coverage of molecular markers and the in-depth study of functional genes, in the future, MAS and GS are expected to accelerate the breeding process of new Ginkgo biloba varieties and achieve targeted improvement of medicinal and ornamental traits (Wu et al., 2019).
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