The industrialized biochemical ability of tissue culture seedlings of horticultural plants can quickly transform excellent varieties into practical productivity, and it will also have great development potential in genetic breeding, germplasm resources protection and secondary metabolites utilization. As long as excellent varieties are selected, the layout is reasonable and the cost is saved, the tissue culture industry will develop vigorously and have broad prospects.

2. 1 Flower industry is the hope industry in 2 1 century, and it is an important symbol of social and economic development and civilization. At present, the demand for flowers in China is increasing by 35% ~ 40% every year. In flower production, the importance of seedling quality in cultivation and production is increasingly obvious, so factory production of flower seedlings is the main way of flower seedling production.

2.2 Vegetable seedling production and virus-free potato, edible lily, garlic, etc. It is the main vegetable on people's table, with large consumption and planting area, and it is also the main variety of China's export to earn foreign exchange. With the increase of planting years, these varieties are susceptible to virus infection, and the yield and quality are declining year by year. Tissue culture and virus-free technology can quickly restore varieties and improve productivity.

2.3 The ellagic acid contained in industrialized strawberry fruit of melon and fruit tissue culture seedlings has anti-cancer effect, and strawberry is easy to cultivate, with high yield and good economic benefits, so it has developed rapidly in Jiangsu and Zhejiang provinces. However, strawberry is easy to be infected with various virus diseases, with deformed fruit and poor quality, and the yield is generally reduced by 30% ~ 80%. Heat treatment combined with meristem culture of virus-free strawberry seedlings can increase yield 1000 kg/667m2, and the quality is also greatly improved. Melon is deeply loved by people because of its crisp meat, rich aroma and sweet taste, which has high benefits, but long-term planting will degrade and mix the quality. Shoots can be taken from strong plants in the field as explants to produce excellent seedlings, and their production characteristics are better than those of seed seedlings. Although they have the characteristics of long delayed seedlings and weak growth potential in the early stage, the seed seedlings after delayed seedlings grow slowly and can surpass the seed seedlings in the later stage, and the seedling stage is shorter, the flowering and fruiting period is advanced, the uniformity is greatly improved, the yield of melons is obviously improved, and the excellent characteristics of collected plants are completely maintained without degradation and variation. European and American grapes are the most popular grape varieties at present, with large fruit, high sweetness, high price and high economic benefits. If tissue culture and rapid propagation technology are used in large-scale production, it will have a good development prospect.

Application of plant tissue culture in horticultural plants;

Using virus-free technology in plant tissue culture can greatly improve the yield and quality of horticultural plants. Many crops are infected by virus, and the yield and quality decrease. Some export crops, such as garlic, lily and mint, have lost their competitive advantage in international trade. By using virus-free technology, the output can be greatly increased. The diameter of garlic increased from 4.7cm to 7.2cm, an increase of 2.5cm, and the weight of garlic increased from 29.2g/ piece to 75.8g/ piece, with an average weight gain of nearly 46g/ piece. After virus-free, the yield of strawberry is increased by 20% ~ 30%, the quality is improved, the virus-free seedlings grow fast, the stems and leaves are strong, resistant to diseases, high temperature and cold, and the life span is prolonged. Virus-free potato seeds are produced in test tubes in the United States, and 1b seeds can replace 1t seed potatoes. This achievement earns $200 million a year. In recent two years, China has produced and popularized virus-free potatoes, which has solved the problem of potato degradation. 666,700 hm2 virus-free seed potato was popularized in the main producing areas, with an increase of 30% ~ 40% and an annual income of 250 million yuan. Virus-free potatoes have been widely used in Japan, the Netherlands, Vietnam and other countries. The planting area of virus-free strawberries in Japan reached 1 13300 hm2, accounting for more than 80% of the total production area. The increase of output 15% ~ 30% can increase the output value 1 1 100 million yen.

Plant tissue culture and industrial production have developed rapidly. Because of the short breeding cycle and high breeding coefficient, it is not limited by seasons and is convenient for industrial production. In the early 1980s, a new industry was formed in the world by using plant tissue and cell culture technology, such as orchid test-tube seedling production in the United States and flower test-tube seedling production in the Netherlands.

Haploid breeding is to induce haploid plants by anther or pollen culture in vitro, and then double their chromosomes to obtain pure lines. The application of this technology in crop breeding can accelerate homozygosity, reduce false selection and shorten the breeding cycle. Anther culture has developed rapidly and achieved remarkable results since it obtained plants in the 1960s. One is to obtain more than 10 plants of wheat, corn, rubber, citrus and other crops, and cultivate more than 50 new varieties of wheat, rice and tobacco, such as Xinxiu, Feng Dan 1, Huayu 1 and Zhonghua Nuo. Cultivated by Li Meifang Crop Research Institute of China Academy of Sciences. Beijing Academy of Agricultural Sciences, Jilin Academy of Agricultural Sciences. Wheat varieties Jinghua 1, Pei Hua L, Jinghua 3, etc. It has been widely used in production, among which the extension area of wheat variety Jinghua No.3 is 60,000 hm2.

Breeding maize inbred lines usually requires continuous selfing for many generations, which consumes a lot of manpower and material resources. Homozygous inbred lines can be obtained by culturing haploid plants with anthers and then doubling chromosomes. Guangxi Agricultural School 1983 used this technology to breed the inbred line Hua 83-2. China has obtained more than 100 maize flower culture pure lines and prepared excellent combinations for production.

Using haploid plants as mutagenic materials, no matter whether the mutation is dominant or recessive, we can see that once excellent mutations are selected, pure lines can be obtained by doubling chromosomes, which can improve the effect of mutation breeding.

At present, anther culture technology has become an effective means to speed up the breeding process, and people are studying this technology more deeply. Wei Xiaoping and other experiments show that adding CPPU in the callus induction stage can advance the induction time of wheat anther callus, and has a significant induction effect on materials that are difficult to culture, and the induced callus can easily differentiate into green seedlings. The experiment of Liaoning Institute of Saline-alkali Land Utilization showed that adding a proper amount of paclobutrazol to the MS differentiation medium of rice could improve the differentiation rate and seedling quality of green seedlings. Wang Pei et al. found that the doubling period of chromosome has an effect on the seed setting rate of winter wheat pollen plants.

There are significant differences in genetic characteristics between parents of distant hybridization breeding, which often lead to cross incompatibility or incomplete development of hybrid embryos and death halfway. Distant hybridization incompatibility can be overcome by in vitro culture of ovary and embryo and in vitro fertilization. If the embryo is taken out at the appropriate stage of hybrid embryo development and cultured in vitro, it is possible to obtain hybrid seedlings and distant hybrid offspring. At present, more than 100 species of plants have been successfully cultivated and applied to crop breeding or production. For example, Bailan, a hybrid of Chinese cabbage and cabbage bred in Japan, has the advantages of both parents. Crops of Chinese Academy of Agricultural Sciences used a similar method to obtain hybrid plants of wheat and corn. Fang Zhiyuan, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences. The materials of 1 and 1, 2, 3 and 4 generations of radish and cabbage were obtained by immature embryo culture. Beijing Academy of Agriculture and Forestry used embryo culture technology to cultivate early-maturing peach Zao 3, which was about half a month earlier than its parents. Tissue culture is used for distant hybridization to create new germplasm resources, which is better in wheat and vegetables and less in rice, and should be strengthened.

Screening system of clonal variation Cells will undergo various variations before in vitro and in vitro culture, which can screen excellent clonal variation and cultivate new varieties. If there is variation in a certain part of plant tissue cells, this part can be separated and cultured in vitro to obtain regenerated plants, and then cultivated into varieties. Applying a certain selection pressure to the culture medium to screen new varieties of clonal variation culture has been successful in many crops, and this technology is especially suitable for resistance breeding. The Department of Biology of Hebei Normal University used the mature embryo of wheat to induce callus, then transferred it to the culture medium containing 0.5% sodium chloride for salt tolerance screening, and then transferred it to the salt differentiation culture medium to obtain the salt-tolerant mutant RS 8901-17 of wheat. After identification, the salt tolerance for three consecutive years was first-class, short and high yield. The Institute of Atomic Energy of Shandong Academy of Agricultural Sciences used γ -rays to irradiate wheat immature embryos for callus culture in vitro, and selected a new variety Hesheng 2 with high yield and good quality. Compared with conventional mutation, mutation of clonal variation at individual level has the advantages of high mutation frequency, fast stability, controllable indoor operation, saving manpower, material resources and financial resources, and improving selection efficiency.

Tissue culture is suitable for the culture and rapid propagation of virus-free seedlings.

Virus-free plants were obtained by tissue culture of plant growth points, which were cultivated and put into production in the 1950s abroad. In the 1970s, experiments in this field began in China. The cultivation area of virus-free potato seedlings has accounted for110 of the national total area, and the yield of virus-free seedlings has generally increased by 50% ~ 100%. At present, in order to improve the virus-free effect,

The rapid propagation of cash crops and ornamental plants is getting hotter and hotter. Many precious flowers are difficult to reproduce because of seed abortion and low survival rate of cutting. The application of tissue culture can promote rapid propagation and mass production, improve economic benefits and preserve fine varieties. Dozens of orchid rapid propagation factories have been established in the United States, Singapore and Thailand, and the planting area of strawberry test-tube seedlings in Japan has exceeded 1 1 000 hm2. According to the statistics of 1990, there are 443 species of fast-propagating plants in China, and more than 1000 institutions have adopted the fast-propagating technology for industrial large-scale commodity production, including rose, chrysanthemum, African violet and butterfly.

Tissue culture is used to preserve germplasm resources and establish gene bank.

Biological preservation has aroused the interest of many researchers, including the preservation of prokaryotes, plants and animal materials. The purpose of germplasm preservation is to ensure that useful germplasm can have vitality at any time. Tissue culture can safely preserve the cells, calli or meristems of plants, and the regeneration process can still occur stably after several years of preservation. It has become an urgent requirement to preserve crops, especially tropical crops, through asexual reproduction. In addition, due to natural and man-made destruction, many strains that have or may have breeding value and can become gene banks are disappearing, and it is usually necessary to preserve crop varieties, parent strains and mutant strains. Tissue culture is superior to field propagation in plant growth and genotype preservation, saving land, labor and energy. Tissue culture materials are small in size, which is beneficial to the long-term preservation of cells that can survive after freezing and thawing. The preservation of germplasm resources and the establishment of gene bank are very important in breeding work.