Studies On The Response And Adaptation Of Chinese Pine Population To Habitat Difference

Chinese pine （Pinus tabulaeformis Carr.）, a species endemic to China, is a mainconstructive species of temperate coniferous forest in northern China. It is important tomake clear the adaptability and variation characteristics of the pine for pine resourcemanagement and utilization. In this study, plant survey and sampling were performed inten plots of natural pine populations in eight Provinces and pine plantations in Chengdecity, Hebei province. The genetic polymorphism, physiological traits, coniferousphenotypic traits and mineral contents were analyzed by molecular marker technique ofinter-simple sequence repeat （ISSR）, analysis of variance, correlation analysis inconjunction with principal component analysis. By analyzing the variation characteristicsof Chinese pine in different habitat conditions, the response mechanisms of Chinese pine todifferent environmental stress were investigated. The results are as follows:The results showed that the modified CTAB was suitable for DNA extraction ofChinese pine. A reaction system with volume of20μL contains2μL10×PCR Buffer(Mg²⁺free),1.0U Taq DNA polymerase,2.0mmol·L-1Mg²⁺,100ng template DNA,0.20mmol·L-1dNTPs and0.4μmol·L-1primer. The optimal amplification program was5min ofpre-denaturalization at94℃;35cycles of30s for denaturalization at94℃,45s of anneal at49℃⁵5℃,2min of extension at72℃; and7min of extension at72℃in the final cycleThere was significant differences in polymorphic loci ratio of natural Chinese pinepopulations among different geographic distribution areas. With a range of0.1923～0.2490,the average value of Shannon’s information indexes was0.2165. Analysis of molecularvariance （AMOVA） showed that inter-population variation was47.55%of the totalmolecular variation. Mantel test showed that the correlation of the pine populationsbetween genetic distance and geographic distance was not significant. Temperature factors（annual mean temperature, the average temperature in January, extreme lowesttemperature）, elevation and rainfall significantly influenced the genetic polymorphism andphysiological characters. There were general geographic variation regularities in molecularvariation of the natural Chinese pine populations. In respond to environmental differenceamong different geographical distribution areas, the definite variation of genetic,physiological and phenotypic traits aroused, but the geographic distance was not the main reason of those variations. The result showed that the genetic diversity of Chinese pinepopulations was closely associated with temperature and water conditions, and the geneticpolymorphism were significantly influenced by the species diversity.The genetic polymorphism level of Chinese pine populations at different altitudes hadsignificantly difference. Chinese pine populations at MH altitude （1274m～1354m） hadthe highest level of genetic polymorphism. Ecological factor at different altitude and lowgene flow greatly influenced genetic differentiation. There was a significant variation ofproline and soluble sugar content in the pine’s leaf between low and high altitude areas.Variation of lignin and cellulose contents increased with elevation changes. Phenotypictraits of Chinese pine population were significantly different in response to elevationchanges. Results indicated that Chinese pine populations in the mid-elevation had thehighest genetic polymorphisms level. Physiological and phenotypic traits of naturalChinese pine populations were significantly affected by habitats conditions at differentaltitudes.The order of Shannon’s information index in Chinese pine populations of differentforest community types was as follows: Chinese pine-Bitch mixed forest＞Chinese pine-Larch-Bitch mixed forest＞Chinese pine pure forest＞Chinese pine-Mongolian oak-Bitch mixed forest. Genetic polymorphism of Chinese pine’s populations among thecommunity types had significant differences. Genetic polymorphism of Chinese pinepopulations was significantly and positively correlated with heights under branch ofChinese pine and Simpson indices of the community. The level of genetic polymorphismsdecreased with increasing soil mineral content. The mineral content of Chinese pine leaf indifferent community types had a significant or most significant difference. Coniferoustraits of Chinese pine leaf, including specific leaf area, dry matter content, leaf area,length/width, were significantly or most significantly different between community types.The level of genetic polymorphisms of Chinese pine-birch mixed forest was higher thanthat of other three community types. Thus the physiological traits and phenotypiccharacteristics of Chinese pine leaf were influenced by different population habitat types.Genetic polymorphism level of the artificial Chinese pine populations increased withthe increasing of damage degrees.71.04%of total genetic variation was fromintra-population while28.96%was from inter-population. The higher the damage degrees,the lower the proline content of Chinese pine. There was no significant difference inproline content of Chinese pine between populations with the middle damage degree andpopulations with the most serious damage degree. There were the highest level of leaf drymatter contents （LDMC） and specific leaf areas （SLA） of Chinese pine in population withthe most serious damage degrees. The results indicated that the level of geneticpolymorphism was in response to different damage degrees of Chinese pine population.With increasing of the damage degrees, the levels of genetic polymorphism increased, stress resistance decreased and physiological activity strengthened.Based on principal components analysis, geographic distributions of high levelgenetic polymorphism populations and major stressing factors were identified. Thisresearch showed that temperature and moisture factors significantly influenced geneticpolymorphism and physiological phenotypic traits of Chinese pine. In the mid-altitude, thelevels of genetic polymorphism and the value of physical-chemical indicators of Chinesepine population were the highest. Chinese pine populations adapted best to the growthcondition in mid-altitude. The deeper the degree of damage, the higher the level of geneticpolymorphism of Chinese pine populations. In summary, the genetic polymorphism,physiological traits, phenotypic traits of Chinese pine were effectively summed up on thebasis of principal component analysis, and furthermore to determine variation and adaptivemechanism of Chinese pine populations in response to environmental discrepancies orstresses.