Self-incompatibility lines of cabbage have been studied in China since 1950s. In the early 1960s, China Academy of Agricultural Sciences Jiangsu Branch and Shanghai Academy of Agricultural Sciences Horticultural Research Institute bred Chen Guangda Pingtou and Heiye Xiaoping self-incompatibility lines respectively, and obtained self-incompatibility lines 103 and 105. In the early 1970s, the Institute of Vegetables and Flowers of Chinese Academy of Agricultural Sciences and other units systematically carried out the research on the self-incompatibility lines and heterosis utilization of cabbage. Through continuous self-crossing, identification and directional selection, seven cabbage hybrids with different maturity and types, such as 7224-5-3 10 and Jingfeng 1, were bred for the first generation of vegetable hybrids in China. In addition, important progress has been made in the study of dominant genic male sterile lines of cabbage unique to China. 200 1 was patented, and five practical dominant male sterile lines with different maturity and types, such as 0 1-2 16MS, were bred, which opened up a new way for hybrid seed production of cabbage. Using these sterile lines as female parents, five hybrids, Zhonggan 16, 17, 18, 19 and 2 1, were bred, which were approved and popularized in production (Fang Zhiyuan, 2002). Chinese cabbage and Chinese cabbage are native to China and are rich in germplasm resources. After long-term improvement, they have formed various kinds and varieties with different maturity and types. In recent 20 years, Chinese cabbage has bred a large number of neat, disease-resistant and high-yield new combinations. The main way of seed production is to breed self-incompatible lines, high-generation inbred lines and male sterile lines. Among more than 200 combinations, there are 55 inbred lines, 2 self-incompatible lines12 and 2 male sterile lines12. The breeding of male sterile lines has bred male sterile dual-purpose lines (single gene male sterility), nuclear gene interactive male sterile lines, Brassica napus male sterile lines and so on. , further enriched the types of parental germplasm resources (Xu, 2002). In the aspect of parent improvement of Chinese cabbage, Nanjing Agricultural University, Shanghai, Guangdong and other provincial (municipal) Academy of Agricultural Sciences have selected a number of inbred lines or male sterile dual-purpose lines from local excellent local varieties, and have prepared a first-generation hybrid dwarf series, dwarf resistant series, black-leaf Chinese cabbage 17, Xia Dongqing and other varieties, which have been widely used in production. China's pepper germplasm resources are rich and diverse, which is conducive to the improvement and innovation of germplasm resources. Zhang Jiren (1980) screened seven excellent local varieties such as Hengyang Fudi pepper and Daoxian Zaopao pepper from Hunan local varieties. The Vegetable Research Institute of Jiangsu Academy of Agricultural Sciences screened out excellent local varieties such as Nanjing Black Shell from local varieties, and then selected a number of new parent materials. The Research Institute of Vegetables and Flowers of China Academy of Agricultural Sciences took Erfutou, Denglong and Luanchuan pepper, two pepper varieties with strong resistance to TMV and CMV, as parents, and Qiemen and Tongfeng No.37 sweet pepper with good economic characters as parents, and screened out 90- 109, 90-1/kl by means of hybridization separation, multi-generation backcross and disease resistance identification. Beijing, Shenyang, Tianjin and other related research institutes have also screened out a number of excellent parent materials. And formed a series of excellent varieties which are quite influential in domestic production, such as Zhongjiao, Xiang Yan, Sujiao, Tianza, Shenjiao, Liaojiao, Hajiao, Jinjiao and Haihua. Similar to pepper, China is rich in cucumber germplasm resources, and a large number of local varieties of various types have become important parent materials of hybrids widely used in production after improvement and innovation by breeders. For example, Tianjin cudgel cucumber and Tangshan autumn cucumber, which are local varieties with good resistance, are used as materials for cross breeding. Another example is local varieties such as Jingji, Changji, Xintai and Ningyang in North China, and Anhui Xiaobaibao, Chengdu Erzaozi, Guangzhou Green Cucumber and Guangzhou Daqing Cucumber in South China, which provide rich germplasm resources for breeding existing series of hybrids (after the wind, 1999). At present, such as Tianjin Cucumber Research Institute's Jinlv, Jinchun and Jinyou series, Chinese Academy of Agricultural Sciences' Vegetable and Flower Research Institute's Middle Agricultural Series, Beijing Series and mini Series of Beijing Academy of Agricultural Sciences' Vegetable Research Center, and Yuexiu Cucumber of Guangdong Academy of Agricultural Sciences, etc. , including the genetic relationship of cucumber in greenhouse in North China, South China and abroad.
There are many examples of improving and breeding new vegetable varieties by using foreign germplasm materials in China, especially tomatoes and hot (sweet) peppers. In 1970s, the tomato variety "Qianglishou" introduced from Japan was not only directly popularized in production, but also selected as an inbred line, which was used as the parent material in China vegetable series tomato varieties bred by Institute of Vegetables and Flowers of Chinese Academy of Agricultural Sciences. Tomato germplasm Manaper Tm-2v introduced from the United States in 1970s is the resistant source of tomato to tobacco mosaic virus, which contains disease-resistant gene Tm-2v. This variety has the characteristics of slow growth at seedling stage, yellowing leaves, late flowering and few fruits. According to the breeding objectives, the Vegetable Research Institute of China Academy of Agricultural Sciences, Jiangsu, Xi 'an, Beijing and other vegetable research institutes have successively cultivated different types of materials containing disease resistance gene Tm-2v, such as pink fruit, limited length and big fruit, and used them as parents to breed China vegetables, Zhongza, Hongza, Su Kang, Jiafen, Jiahong, Xifen, Puhong, Zhehong, Zhefen and Donghong. According to incomplete statistics, the annual seed production of the first generation hybrids containing Tm-2v gene cultivated by the above-mentioned units exceeds 654.38+10,000 kg, accounting for about 50% of the total consumption of commercial tomato seeds in China, and the cumulative extension area is about 667,000 km, which greatly reduces the harm degree of tobacco mosaic virus (TMV) in China, improves the market supply, and has remarkable social and economic benefits. Another example is Ohio -MR9, which was introduced from the United States and contains a series of genes against leaf mold. After improvement, it was transformed into disease-resistant materials, and a large number of tomato varieties were cultivated in open field and protected field. In addition, six tomato varieties with different genes selected by British Greenhouse Crops Research Institute, which were introduced from Japan, played an important role in identifying the harm of tomato tobacco mosaic virus (TMV) in China (Li Shude, Feng, 1995). On the basis of introducing foreign excellent germplasm resources of hot (sweet) pepper, such as excellent disease-resistant materials, powdery mildew-resistant materials such as, CI, PRIMOR, and two commercial varieties with disease resistance introduced from France by Institute of Vegetables and Flowers of Chinese Academy of Agricultural Sciences, six strains superior to Solanum were screened by pedigree selection method, among which four strains were moderately resistant to cucumber mosaic virus (CMV) and tobacco mosaic virus (TMV). The new cucumber germplasm "G5224" innovated by the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences combines the advantages of Spinibarbus beijingensis, European varieties and American varieties, showing the characteristics of all-female, extremely early maturity, low temperature tolerance, high resistance to angular leaf spot, Fusarium wilt, scab, powdery mildew and downy mildew, realizing the aggregation of disease-resistant gene sources of different blood families. The new germplasm "16 13" comes from the hybrid line of cucumber and Nitraria tangutorum in European greenhouse, showing strong females, extremely early maturity, low temperature tolerance, high resistance to angular leaf spot and Fusarium wilt, scab, powdery mildew and downy mildew. In addition, a new potato germplasm "Zhongshu 9408- 1" was created by taking advantage of the excellent processing disease-resistant strain S452 with wild blood relationship and the excellent fried chip processing variety Atlantic. The color of fried chips is 2.5 (American fast food association standard 1 ~ 10, with 1 being the best), and the relative density (indoor inoculation identification shows that it is resistant to potato X virus and highly resistant to potato Y virus; Field identification of potato resistance to late blight. This will play an important role in changing the situation that the processed varieties in the domestic potato market are monopolized by foreign varieties. The above results show that the improvement and innovation of vegetable germplasm resources by conventional hybridization, separation, backcross and selection are still the main methods adopted at present, and the effect is remarkable.
In addition to the above methods, in recent years, excellent parent materials have been cultivated by anther and isolated microspore culture techniques. Anther and pollen culture is an effective method to obtain excellent pure lines quickly. Compared with conventional multi-generation self-crossing, it has the characteristics of short cycle, high efficiency and stable pure line. Isolated microspore culture also has the advantages of single cell haploid, large population, good natural dispersion, no interference from recipient cells, convenient genetic operation and so on, and can quickly obtain high-purity haploid materials. Henan Institute of Biotechnology has successfully cultivated and propagated 8 varieties of Chinese cabbage in the past 65,438+00 years, with an extension area of 200,000 kilometers. This is a successful example of microspore culture technology in vegetable germplasm resources innovation and genetic breeding. In addition, isolated microspores of Brassica, Mustard, Chinese Cabbage, Chinese Cabbage, Cabbage and Turnip were continuously cultured and regenerated plants were obtained (Jiang Wusheng et al., 2002). Haihua No.3, the first flower-cultured sweet pepper variety in China, was bred by anther culture in Haidian Plant Tissue Culture Technology Laboratory with Ping 'an Rongguang variety introduced from Japan. Pepper Haihua 1 was bred from Bulgarian pepper by flower culture method. With the flower culture line as the parent, more than 10 Haifeng series hybrids were further bred and popularized in large areas in production. In addition, after years of research, Zhangjiakou Vegetable Research Institute has cultivated a flower cultivar "Saihua" and popularized it in production (Zou, Jiang, 2002). Isolated microspore culture and anther culture technology have opened up a new way for the improvement, innovation and genetic breeding of vegetable germplasm resources at the cell level.
In recent years, protoplast culture and somatic hybridization techniques have also been used to improve and innovate vegetable germplasm resources. Regenerated plants were obtained by protoplast fusion of seven fusion combinations of carrot, and petal-shaped male sterile lines of carrot were successfully transferred in 1 fusion combination. Somatic hybrid plants of six excellent eggplant varieties and two wild eggplant distant varieties were obtained by protoplast fusion, and the disease resistance genes in wild eggplant were transferred to common eggplant (Li Xixiang et al., 2006).
In addition, plant genetic engineering has also made some new progress in the improvement and innovation of vegetable germplasm, such as successfully controlling the utilization of mature genes in vegetable fruits. Ye Zhibiao and others used tomato ethylene forming enzyme (EFE)cDNA clone to construct antisense vector, transformed cotyledon explants with Agrobacterium Ti plasmid, and cultured the infected explants with Agrobacterium * * * to regenerate complete tomato plants. After testing, the introduced marker gene can be passed on to future generations. EFE activity and ethylene production of these two transgenic lines were obviously inhibited, which was lower than that of the control (10%). The storage test showed that after 88 ~ 92 days of storage, the good fruit rate of transgenic plants was still above 80%, which was 8 ~ 10 times longer than that of the control, while other characters were similar to those of the original parents (Ye Zhibiao et al., 1995).