This project belongs to the field of vegetable genetics, breeding and molecular biology. Molecular marker-assisted selection and the utilization of male sterility have become the main techniques in cabbage breeding. This project combines molecular markers with male sterility technology to carry out innovative utilization of cabbage germplasm resources and hybrid breeding and promotion. The following main results have been achieved: Genetic diversity and clustering of cabbage germplasm resources were carried out using SRAP technology. Analysis provides a basis for the preparation of cabbage hybrid combinations. For the first time, a molecular marker patent closely linked to the immature bolting gene of cabbage was obtained, and was successfully applied to molecular marker-assisted selection to obtain excellent immature bolting tolerant materials, such as 2004-30, i.e. ldquo; Zhengniu rdquo; cabbage male parent. Using my country's unique cabbage male sterile resources, we creatively obtained cabbage materials that can be naturally fruited through mixed recurrent selection of 12 genetic sterile hybrid combinations, such as 2008-137 (ldquo; Zhengmei rdquo; cabbage male parent), SHF-3-180-134 (ldquo; round green rdquo; cabbage male parent), changing the traditional practice that cabbage parents must rely on artificial bud peeling and pollination for self-pollination. Using the above-mentioned nuclear male sterile sources, a dominant homozygous nuclear male sterile line was obtained through a combination of backcrossing and molecular marker-assisted selection, which has been used for the preparation of nuclear male sterile hybrids, which is significantly improved compared with the preparation of hybrids using self-incompatible lines. Seed purity. A radish cytoplasmic male sterile source is utilized, and a good inbred line is used as a recurrent male parent to carry out cytoplasmic male sterile line transformation, so that cabbage cytoplasmic male sterile lines with good combining ability and no degeneration are obtained, such as CMS-101, i.e., cabbage female parent;CMS-109, i.e., cabbage female parent; and CMS-109, i.e., cabbage female parent. Three new cabbage varieties with strong heterosis were bred by using the excellent parent materials. They participated in the national cabbage variety regional test and passed the identification of the National Vegetable Variety Identification Committee. amp;ldquo; Zhengniurdquo; Cabbage is recommended as the leading cabbage variety in Shanghai City. It has a cow heart-shaped shape and a higher price than ordinary oblate cabbage. The existing ldquo; cow-heart-type cabbage varieties are mainly cultivated for spring cabbage, while the new ldquo; Zhengniu rdquo; cabbage varieties are resistant to immature bolting and can be cultivated for both spring cabbage and autumn cabbage, effectively supplementing the market gap of cow-heart-type cabbage in autumn and winter. amp;ldquo; Zhengmei rdquo; Cabbage is a round-shaped variety. Compared with similar domestic varieties, its leaves are crisp, tender and of excellent quality. amp;ldquo; round green rdquo; cabbage has an average maturity period of 59 days in the national regional test, which is 4 days earlier than the control ldquo; hope rdquo; and is the most early among all tested varieties. This project also constructed a DNA fingerprint of cabbage varieties, providing a scientific basis for rapid identification and intellectual property protection of cabbage varieties. This technology is used to conduct strict purity identification of cabbage seeds produced by the base to ensure timely provision of seed quality information before large-scale transactions, ensuring the high purity and high reputation of the seeds sold. This project has produced good economic and social benefits. From 2016 to 2018, cabbage seed production added 607,500 yuan to the output value of base farmers. The company distributed 4845 kilograms of cabbage seeds with a purity of more than 98%, creating a direct profit of 1.0659 million yuan. According to the cooperation agreement, cabbage varieties such as ldquo; Zhengniu rdquo;, ldquo; Zhengmei rdquo;, ldquo; Yuanlu rdquo; are preferentially applied in Shanghai Xinghui Vegetable Co., Ltd., and are produced in strict accordance with ldquo;Q/VBKS2 - 2014rdquo; Shanghai City Enterprise Standards. A total of 18,700 acres were planted in three years, with an additional profit of 22.814 million yuan. In addition, these varieties have also been promoted to Jiangsu, Anhui, Zhejiang, Henan, Hebei, Gansu and other provinces and cities. According to statistics from the supporting materials received, the cumulative planting area is 150,100 acres, and the cumulative new social benefits are 49.4206 million yuan. This project has obtained 1 authorized invention patent, 3 nationally identified varieties, 1 Shanghai City Enterprise Standard, 5 invention patents have been applied, and 20 representative papers.