Progress of collection, conservation and innovative utilization of Prunus mume resources in the National Prunus mume and Chinese Bayberry Germplasm Repository (Nanjing)

Japanese apricot (Prunus mume) is native to China and has a long history of cultivation with abundant germplasm resources. As one of the important drupe fruit crops in China, it plays a vital role in the horticultural industry and exhibits extensive genetic diversity. This genetic diversity offers invaluable material support for advancing Prunus mume breeding, and ensuring sustainable development of the industry. This paper comprehensively introduces the development process of The National Prunus mume and Chinese Bayberry Germplasm Repository (Nanjing), summarizes and reviews the collection and conservation status of Prunus mume germplasm resources since the establishment of the repository, as well as research on these resources and their innovative utilization. It also provides an overview on the future development of the repository, offering valuable reference information for the effective utilization of Prunus mume germplasm resources and the sustainable development of the industry in China. This study aims to provide valuable insights for the effective utilization of Prunus mume germplasm resources. By ensuring the sustained conservation and management of resources at the National Prunus mume and Chinese Bayberry Germplasm Repository (Nanjing), we seek to integrate these materials into the sustainable development of the Prunus mume industry. Furthermore, this effort aligns with broader goals of advancing agricultural sustainability in China. The National Prunus mume and Chinese Bayberry Germplasm Repository (Nanjing), affiliated to Nanjing Agricultural University, is the only national Prunus mume germplasm resources in China. It is the world’s largest, most comprehensive, and well-organized germplasm resource nursery for Prunus mume, based on the number of collected and preserved accessions. By the end of December 2024, The National Prunus mume and Chinese Bayberry Germplasm Repository had collected and preserved a total of 351 Prunus mume germplasm accessions, with 265 accessions cataloged and conserved in the repository. These resources have been sourced from various regions, including Jiangsu, Zhejiang, Guangdong, and other provinces. A systematic identification and evaluation of Prunus mume germplasm resources have been conducted, leading to the identification of 29 outstanding accessions. In-depth applied research has focused on understanding the domestication and propagation of Prunus mume resources, elucidating the molecular mechanisms underlying dormancy release, and studying the development of pistils. Another key area of research has been disease resistance, which is crucial for maintaining healthy crops in the face of evolving environmental challenges. The sequencing of 146 Prunus mume germplasm resources from different geographical regions, combined with whole-genome resequencing and chloroplast genome analysis, has revealed two major propagation routes. The first route follows the Yangtze River channel, spreading from southwestern China to Hunan, Jiangxi, and Anhui, and finally reaching Yunnan, Jiangsu, Zhejiang, and Shanghai, while the second route mainly follows the Pearl River channel, spreading from southwestern China to Libo in Guizhou, as well as Guangdong, Fujian, and Taiwan. It was also revealed that Prunus mume resources mainly originated from the Zhejiang region of China. Meanwhile, many genes related to sugar metabolism and aromatic compound metabolism were significantly enriched during the domestication and improvement of Prunus mume. In addition, natural variation of the PmCBF03 allele was identified to be involved in the regulation of temperature acclimatization of Prunus mume in different ecological zones. Regarding Prunus mume dormancy release mechanisms, the chilling requirements of 75 cultivars from the National Prunus mume and Chinese Bayberry Germplasm Repository were assessed, showing a wide range. Based on the degree of aggregation of chilling requirements and flowering period of Prunus mume varieties, we have categorized them into low chilling requirement varieties (＜50 CP), medium chilling requirement varieties (50-70 CP), and high chilling requirement varieties (＞70 CP). Changes in abscisic acid (ABA) and gibberellin (GA) content in Prunus mume buds play an important role in dormancy release, and applying 200 μmol·L-1 GA4 when chilling accumulation reaches about onethird of the required level effectively breaks dormancy, promoting early bud break and flowering. Multiomics analysis, including proteomics, transcriptomics, and metabolomics, has revealed that GA4 treatment activates hormone- related genes such as PmRGL2, PmDAM6, PmNF-Y, and PmSVP involved in dormancy regulation. In pistil morphogenesis, the PmWUS gene shows significantly higher expression in multi-pistil cultivars during early differentiation and development compared to single-pistil cultivars, with its suppressor PmAG following a similar trend, suggesting the involvement of additional regulatory factors in PmWUS modulation during Prunus mume pistil formation. Over the past decade, the National Prunus mume and Chinese Bayberry Germplasm Repository has provided 2000 usable accessions to Chinese universities, research institutes, production units and individuals. In recent years, the repository has made valuable contributions to breeding 12 new high-quality Prunus mume cultivars, such as Nanhong, Nannong Longxia and Nannong Fengjiao. In addition to breeding efforts and enriching cultivar structures, the National Prunus mume and Chinese Bayberry Germplasm Repository has played a crucial role in rural revitalization and the sustainable development of the Prunus mume industry by providing a platform for scientists, farmers, and industry stakeholders to access high-quality genetic material, fostering innovation and collaboration in the field of fruit tree cultivation.