Effect of different carbon source and nitrogen source on the cold resistance of citrus callus inductionHu Siyuan (College of Agronomy, Northwest A&F University, Yangling, Shaanxi ,China)Abstract: Citrus callus is ideal material for physical and chemical mutagenesis and genetic transformation, the carbon source and nitrogen source is a necessary component in the induction and subculture of citrus callus, so the exploration of carbon, nitrogen sources is of great significance to the effect degree of citrus callus induction and effect way. This study choose cold resistance of citrus as test material, through culture vitro tissues, analysis of the effects of carbon source and concentration, nitrogen source and level on the influence of citrus callus induction, To provide the basis for the study of the occurrence and the mechanism of cold resistance of Citrus genetic improvement, somatic embryos.Key words: carbon source; nitrogen source; citrus; callusIntroductionCitrus (Citrus reticulata Blanco) Rutaceae Citrus, small evergreen tree or shrub, about three meters high, weak branches, usually with thorns. Leaves are alternate, leathery, lanceolate to ovate-lanceolate, 5.5-8 cm long, 2.9-4 cm wide, apex acuminate, base cuneate, entire or with fine blunt teeth, petiole slender, winged obvious . Flowers small, yellow-white, solitary or clustered in leaf axils, sepals 5; petals 5; stamens 18-24, filaments 3-5 pieces often connate, ovary 9-15 rooms. Citrus fruit flat spherical, 5-7 cm in diameter, orange-yellow or reddish yellow, peel loose flesh meat easily separated.Chenggu citrus cultivation has a long history dating back more than 2,000 years of history. Chenggu County is located in Southern Shaanxi, Central Hanzhong Basin, north subtropical to temperate transition region, north of Qinling mountain blocking the invasion of cold northwest, south winds Bashan so warm air can not drive straight. Inversion effect Qinling belt and foothills sloping wall, forming a unique micro-climate regions, fewer winter cold and summer heat less. First, heres citrus high temperature hot wind does not harm flowering, fruit setting rate; Second cool early autumn, temperature, and is conducive to fruit color, ripe, citrus fruit surface here is gorgeous, high soluble solids content, moderately sweet and sour.Studies1-4 have shown that by changing the carbon source to induce somatic embryogenesis. As most of the citrus callus has not regenerate embryoid body phenomena 5-7, while the high-frequency induction of somatic embryogenesis of citrus cells for genetic transformation, in vitro mutagenesis, in vitro screening mutants, rapid propagation, etc. work has special significance 8-9. In this paper, sucrose, glucose, soluble starch, three kinds of carbon and nitrogen sources ammonium nitrate one kind of growth and the ability of somatic embryogenesis of citrus callus were studied at different levels, in order to select the optimal culture conditions hardy citrus studies provide evidence.1. Purpose and significance 1.1 Purpose 1. Analysis the influence of carbon types and carbon levels on hardy of citrus in vitro cultured explants dedifferentiation;2. Explore the nitrogen source for citrus callus induction effect manner and extent of effect;3. Screening suitable carbon, nitrogen conditions of citrus dedifferentiation in vitro callus induction.1.2 Significance Citrus Calli is an ideal material for the physical and chemical mutagenesis and genetic transformation, and carbon and nitrogen is a necessary ingredient in citrus callus induction and subculture, therefore it is important to explore the extent and the effect of the way on citrus callus induction of carbon source, nitrogen source.1. Explore the carbon and nitrogen sources for citrus callus induction effect, especially on the induction rate and differentiation speed for in-depth study of carbon and nitrogen in the mechanism of tissue culture citrus from the body, and to provide some data to support ;2. Hanzhong citrus varieties for the study material, try to filter out the best of its callus induction of carbon required, the type and content of nitrogen for the production of virus-free citrus seedlings through callus ideal way to provide relatively basic culture conditions.2. Materials and methods2.1 MaterialsSeeds of the test material explants of the same size, healthy full Chenggu hardy citrus varieties.2.2 Preparation2.2.1 InstrumentHS series horizontal flow bench (Suzhou Antai Air Technology Ltd.); the dish; vertical circular chamber pressure steam sterilizer (Shanghai Medical Nuclear Instrument Factory); portable electric pressure steam sterilizer (Shandong Xinhua Medical Instrument) electronic balance (Shanghai balance Instrument Factory); electric distilled water (Shanghai medical nuclear Instrument Factory).2.2.2 Auxiliary materials(1) In a planned way of cleaning the glassware (Erlenmeyer flasks, petri dishes, etc.),