Progress of collection, conservation and innovative utilization of peach resources in the National Peach and Strawberry Germplasm Repository (Nanjing)

Peach [Prunus. persica (L.) Batsch] belongs to the small-type deciduous trees of the genus Prunus in the family Rosaceae, and is classified as a stone fruit tree in horticultural taxonomy. As an important economic fruit crop, its cultivation history can be traced back to the Neolithic Age. China is the origin center of peaches, with rich genetic diversity. The global genus Prunus contains approximately 300 species, among which Prunus persica and its related species (such as Prunus kansuensis, Prunus davidiana, Prunus mira, etc.) form an independent taxonomic unit. Modern taxonomic studies show that under the peach species, it can be subdivided into wild populations, cultivated variety groups (such as honey peaches, nectarines, flat peaches, yellow-fleshed peaches, etc.), and related wild species. China preserves more than 3000 peach germplasm resources, accounting for over 70% of the global total. The artificial domestication process of peach trees is deeply intertwined with the evolution of Chinese civilization. Archaeological evidence shows that wild peach stones have been found at the Hemudu Site in Zhejiang, China (approximately 7000 years ago). Records in the‘Shijing’during the Shang and Zhou dynasties indicated that peach trees had already been endowed with cultural symbolic meanings.In the Han Dynasty, through the Silk Road, peaches were transmitted from Central Asia to Persia (present-day Iran), and later gradually spread to Europe, the Americas, and temperate regions worldwide. In the 16th century, European colonizers introduced peach trees to the American continent. After the 19th century, three major global peach industrial belts centered on California in the United States, Italy, and China were formed. As the genetic diversity center of peach trees, China exhibits significant geographical regionality in the distribution of wild resources: The northeastern Tibetan Plateau (such as Aba in Sichuan and Gannan in Gansu) is home to primitive populations like Prunus mira. With small fruits and high oil content, they serve as important genetic resources for studying stress resistance in peach trees. The Loess Plateau in northwestern China (Shaanxi, Gansu, and Ningxia) is a concentrated distribution area for Prunus davidiana and Prunus kansuensis. These wild species are drought- and cold- resistant, often used as rootstocks for cultivated peaches. The Hengduan Mountains in southwestern China (Yunnan, and southwestern Sichuan) preserve wild fuzzy peach types unique to the Yunnan- Guizhou Plateau, featuring strong stress resistance and low chilling requirements. Additionally, the North China Plain and the middle-lower Yangtze River region are the evolutionary centers of cultivated peach varieties, forming classic groups such as Southern Honey Peaches and Northern Hard-Fleshed Peaches. Since 1956, China has carried out peach resource surveys in multiple regions across the country, basically identifying 6 species and 16 varieties or types of the genus Prunus. In the early 1980s, three national peach germplasm resource nurseries were established in Beijing, Nanjing, and Zhengzhou, preserving more than 1000 germplasm resources. By 2024, a total of over 4000 peach germplasm resources had been collected and preserved. The National Peach and Strawberry Germplasm Resource Repository (Nanjing) is one of the three major peach germplasm conservation units in China, focusing on the collection and preservation of southern peach germplasm resources. By the end of 2024, it had collected and preserved more than 1300 peach germplasm resources, including six species: P. persica (L.) Batsch, P. mira Koehne, P. davidiana (Carr.) Franch., P. potanini Rehd., P. kansuensis Rehd., and P. ferganensis (Kost. et Kiab) Kov. et Kost., as well as varieties such as flat peach (P. persica var. compressa Bean.), nectarine (P. persica var. nectarina (Ait.) Maxim), ornamental peach, and dwarf peach. In the early stage, the evaluation of germplasm resources in the National Peach and Strawberry Germplasm Resource Repository (Nanjing) focused more on high quality, storage tolerance, and diversification. With the progress of the times and industrial development, the main cultivated peach varieties in production face some problems such as narrow genetic backgrounds, reduced resistance to pests, diseases, and abiotic stresses, potential risks of pest and disease outbreaks, and large yield fluctuations caused by adverse weather conditions. As the origin and evolutionary center of peaches, China is rich in peach and its wild related species. Diverse wild resources and local varieties provide important materials for expanding the genetic background of peach varieties and creating or breeding multi- resistant varieties (lines) or those with high functional component content, and also provide a material guarantee for the sustainable development of the peach industry. Therefore, it is of great significance to strengthen the collection and preservation of wild resources and local varieties in response to China’s peach industry needs. Based on the original focus on high quality, storage tolerance, and diversification, this nursery has combined practical production issues to focus on traits such as disease resistance (resistant to gummosis and brown rot) and adaptability (low chilling requirement, and waterlogging tolerance). Through identification and evaluation, more than 30 germplasms with resistance to gummosis, low chilling requirement, red-fleshed peaches, dual-purpose ornamental and fresh-eating peaches, narrow-leaf peaches, columnar peaches, storage- tolerant germplasms, and those with excellent quality traits have beenscreened out. Over the years, the National Peach and Strawberry Germplasm Resource Repository (Nanjing) has obtained a large number of genetic materials and excellent individual plants through hybrid combinations, promoting the development of basic research such as peach origin studies, molecular marker development, and functional gene analysis, and assisting in germplasm innovation, variety breeding, quality improvement, and resistance breeding. It has promoted the optimization and adjustment of peach variety structures, providing support for the safe preservation and effective utilization of peach germplasm resources in China and the healthy development of the peach industry. In the future, combining technologies such as genomics and molecular marker-assisted breeding to deeply explore excellent genes in wild resources will become a key direction to break through the narrow genetic basis of cultivated varieties and enhance industrial competitiveness.