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

Strawberries (Fragaria spp.) are perennial herbaceous plants belonging to the Fragaria genus of Rosaceae family, and classified as small berries in horticultural classification. There are approximately 26 species, including 14 diploid species, 5 tetraploid species, 1 pentaploid species, 1 hexaploid species, 3 octoploid species, and 2 decaploid species. Among them, only the octoploid species (Fragaria × ananassa Duch.) is economically cultivated, while the rest are in a wild or semi-wild state. The history of strawberry cultivation began in the early 14th century due to its edible value. However, the modern cultivated large-fruited strawberry (Fragaria× ananassa Duch.) with high heterozygotes originated from a natural hybrid between the two American species, F. virginiana Duch. (2n = 8x) and F. chiloensis Duch. (2n = 8x) in France around 1750. It was quickly introduced for cultivation in European countries such as the United Kingdom and the Netherlands, and later gradually introduced to other countries. According to records, in 1915, the cultivated variety Victoria was introduced to Liangzipo in Heilongjiang Province, marking the beginning of strawberry cultivation in China. Strawberry ranks first in cultivation area among the small berries. China is the largest strawberry production country with the richest wild species in the world. Of about 26 recognized Fragaria species, 15 are distributed in China, including 10 diploid species, and 5 tetraploid species. Regions such as the Changbai Mountains, the Tianshan Mountains, the Qinling Mountains, the Tibetan Plateau, and the Yunnan-Guizhou Plateau are all natural gene banks of wild strawberry resources. The National Peach and Strawberry Germplasm Resources Repository (Nanjing) is an important institution for the safe preservation, sharing, and utilization of strawberry germplasm resources in China. It is characterized by its strategic, fundamental and public welfare nature, and undertakes crucial tasks including the investigation and collection, preservation, accurate evaluation and identification, as well as sharing and communication of strawberry germplasm resources. As the supporting organization of the National Peach and Strawberry Germplasm Resources Repository (Nanjing), the Jiangsu Academy of Agricultural Sciences has been engaged in the collection of strawberry germplasm resources and breeding new varieties since the 1950s. Since 2001 in response to the issue that China is rich in wild strawberry resources but lacks a clear understanding of their basic background information, it has systematically surveyed wild strawberry germplasm resources in the original habitats such as the Changbai Mountains, the Tianshan Mountains, the Tibetan Plateau, and the Yunnan- Guizhou Plateau. The survey covered more than 20 provinces and cities across the country. As a result, 513 strawberry germplasm resources have been collected and preserved, and the geographical distribution of 15 wild species in China has been clarified. The National Peach and Strawberry Germplasm Repository (Nanjing) preserves the largest numbers of species and accessions of strawberry in the country. Up to December 2024, The Germplasm Repository has collected and preserved over 1100 strawberry accessions, covering 23 out of the 26 species in the strawberry genus worldwide. As the leading unit for cataloging strawberry germplasm resources in China, the National Strawberry Germplasm Resources Repository (Nanjing) has collected data such as the phenotypic traits of plants, ploidy, pollen morphology, and fruit traits through botanical observations, ploidy detection, palynological observations, etc. It has established methods for identifying and evaluating resources, including determining the species based on phenotypic traits, using flow cytometry for ploidy identification and assessing the genome size, and detecting fruit quality through HPLC (High Performance Liquid Chromatography) and GC-MS (Gas Chromatography- Mass Spectrometry). It has compiled the Descriptors and Data Standard for Strawberry (Fragaria spp.), formulated and co- formulated three industry standards, including the Descriptors for Strawberry Germplasm Resources, the Evaluating Standards for Elite and Rare Germplasm Resources— Strawberry (Fragaria spp.), and the Technical Code for Evaluating Germplasm Resources- Strawberry (Fragaria spp.), unifying the standards for the identification and evaluation of strawberry germplasm resources across the country. The National Strawberry Germplasm Resources Repository (Nanjing) ranks first in China and among the top internationally in terms of the quantity of germplasm resources preserved. To ensure the safe conservation of strawberry germplasm resources, it has established a threelevel conservation system, namely conservation of all resources in potted plants in glass greenhouses + in-vitro conservation of important resources + low-temperature conservation of precious resources. The rich strawberry germplasm resources provide a solid material foundation and technical support for basic strawberry research, new variety breeding, industrial development, as well as display and promotion. It provides material basis and data support for tracing the origin of the Fragaria×ananassa Duch., developing molecular markers, analyzing functional genes, innovating germplasm and breeding varieties. Moreover, the successful breeding of early- maturing strawberry cultivars such as Ningyu, Ningfeng, and Zijin Jiuhong, with disease resistance, has filled the gap of early-maturing strawberry varieties in China. This review introduces the construction process of the Germplasm Repository, outlines the current status of strawberry resource preservation, innovative utilization, and prospects for future research directions, in order to provide strong support for the safe preservation and effective utilization, and promote the healthy development of the strawberry industry.