Progress of collection, conservation and innovative utilization of germplasm resources in Pear Branch Center of the National Horticulture Germplasm Repository (Zhengzhou)

Pear is one of the main deciduous fruit trees with the longest cultivation history and the most extensive distribution in China. As the most important origin of Pyrus L. in the world, it is rich in variety resources and is also the world’s largest pear producing country. The National Horticulture Germplasm Resources Center Pear Branch Center (Zhengzhou) was established in 1978. It covers an area of 30 acres and is located in Zhengzhou, Henan Province. Its geographical location is 113°42' E and 34°48' N, with an altitude of 110.4 m, an annual average temperature of 14.0 ℃, an average annual precipitation of 636.7 mm, an annual sunshine of 2 385.5 hours, and a frost-free period of 213 days (semi-arid monsoon continental climate) and the geographical location is superior. The Pear Branch Center (Zheng-zhou) primarily engaged in the collection and preservation, identification and evaluation, sharing and utilization, germplasm innovation, service to the industry, and science education of pear germplasm resources. It is one of the important preservation nurseries of pear germplasm resources in China. At present, a total of 560 pear germplasm resources of 14 species are preserved. It provide resource sharing to universities, research institutes, government departments, and enterprises, and receive more than 1000 visitors or trainees annually, as well as the demonstration and promotion of new varieties, new technologies and new patterns. The collection, preservation, identification, and evaluation of germplasm resources are important foundations for the development and scientific research of the pear industry. The team of Pear Branch Center (Zhengzhou) has completed the collection of basic phenotypic data and image data of flowers, fruits and annual branches of pear germplasm resources through systematic evaluation of germplasm resources. Some quality traits of the germplasm resources, such as soluble sugar acid, polyphenols, fruit spots, browning, sepals, texture and so on, were accurately evaluated. On the basis of these works, a number of specific resources with high sugar content (Soluble solids more than 16% ), suitable processing (pear juice remains un-browned 4 days at room temperature), accessions with high resistance to decay were identified, which provided a germplasm resource basis for the genetic improvement of varieties. In order to adapt to the structural adjustment of agricultural modernization and the changes to the supply and demand of the pear market, the team of Pear Branch Center bred a batch of excellent varieties, such as Zhongli No. 1, Hongxiangsu and Meirensu using the rich pear germplasm resources once being the main varieties in the industry. The team have also bred some new pear varieties such as Qiyuesu, Zaobaimi and Zaosumi, contributing a lot to the industrial development and Rural Revitalizatio, vinning a number of national, provincial and ministerial awards. Some excellent varieties, characterized by early maturity and red skin, such as Danxiahong, Hongsumi, Hongsubao, Zaohongyu, and Zhonglijinfu have been successfully licensed. Based on the rich germplasm resources of Pear Branch Center (Zhengzhou), the basic research work such as the DNA fingerprint of pear germplasm resources, the construction of trait evaluation criteria, molecular marker development, genome sequencing, excellent gene mining and other works were carried out. Three generations of high-quality Hongxiangsu genome, the genome chromosome level assembly of Hongxiangsu pear and the high-quality genome assembly of Danxiahong with haplotype- resolved telomere- to- telomere (T2T) accuracy were completed. The evaluation criteria of pear flesh browning and fruit spot traits were established. The molecular markers related to red shoot, full red skin, fruit size, pulp browning, fruit peel spot, annual branches, leaves and other traits were developed, and the candidate genes regulating pear red/green skin, flesh browning, fruit spot development and other traits were found. All them findings have laid a foundation for molecular breeding and important characters research of pear. This team integrated the efficient cultivation technology for quality pear which were selected as the main agricultural technology in 2019. These new varieties and technologies have made important contributions to the structural adjustment of pear varieties, rural revitalization and sustainable development of the pear industry in China. In this paper, the research progress of germplasm collection and preservation, characteristic germplasm screening, germplasm innovation and utilization in the National Horticulture Germplasm Resources Center Pear Branch Center (Zhengzhou) over the past decade were reviewed, and the main problems and suggestions were proposed. to give a clue for the effecient utilization of pear germplasm resources and pear industrial development in China.