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Citrus is the world's most important economic fruit, very popular. Citrus is a chills the thermophilic, avoid salinity fruit trees. Periodic damage, sudden cold wave and tidal wetland Saline Soil, transitional farming secondary salinization, to varying degrees, affect the yield and quality of citrus. Research citrus cold, the physiological changes and resistance to regulation under salt stress has important theoretical and practical significance. In this paper, the growth uniformity, easy to control stress conditions callus system, the different varieties of citrus callus physiological changes in the face of adversity, Exogenous Polyamines on stress resistance regulation and polyamine synthesis enzymes Isolation and expression of the gene SAMDC made a preliminary study. The main findings are as follows: 1. Citrus Calli salt (NaCl) stress (0mmol/L-200mmol/L) 35d determination of weight gain: low salt concentrations, especially 25 mmol / L on the growth of callus role in promoting. More than 150 mmol / L, the callus growth was inhibited callus large number of deaths, 200 mmol / L or more. The difference in performance between the different varieties of structure-head orange strong salt stress less than 150 mmol / L salt, followed by Ningbo kumquat, Newhall worst. 2. Citrus callus chilling stress (4 ° C, 0h-9d) the treated culture 35d determination of the weight gain found: low temperature stress 12h and 24h obviously promote the growth of callus, and low temperature stress 5d, slow growth, low temperature stress 9d growth basically stopped. Different varieties also showed differences in the structure-head orange low-temperature performance is more sensitive to stress 5d callus proliferation has slowed down significantly. 3. : With the growth of the stress time, the value of the performance of the relative electrical conductivity continues to rise, a greater increase in less than 24 hours in the research of salt stress on the of Citrus Calli conductivity and MDA content; Similarly, C the dialdehyde content is gradually increased with the stress of time longer; contrary, found in 4 ° C low temperature stress, the relative conductivity change is not significant increase in malondialdehyde content. That high salt stress in the cell membrane was greater degree of injury. 4. The plus 0.5mmol/LSpd promoting the growth of callus. 0.5 mmol / L Spd same role in promoting the growth of salt stress under low temperature stress callus. In the short time of salt stress and cold stress, the SPD greatly promoted the proliferation of the callus. The stress of the longer period of time, the role of the SPD is not obvious. Found in the further determination of relative conductivity, the conductivity of the callus under salt stress Spd decreased under low temperature stress added little change before and after the SPD callus. 5. Through the SAMDC gene fragment was separated polyamine gene expression studies. The SAMDC gene fragment (743bp) separation, after the semi-quantitative RT-PCR study: low temperature stress, stress callus SAMDC expression were increased, especially in the stress 1d rise more obvious, and film the degree of injury
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