Study On Difference And Genetic Character Of Main Traits Among Different Types Of Nicotiana Tabacum L.

According to the quality of tobacco leaf characteristics, biological characteristics and cultivation methods, Nicotiana tabacum is divided into flue-cured tobacco, sun-cured tobacco, air-cured, burley and oriental tobacco in China. Flue-cured tobacco is the most important type in international tobacco production, currently. So the tobacco breeder play most attention in flue-cured tobacco variety development and neglected the useful trait of other types in improving the tobacco variety, causing the genetic background of the cultivars is very narrow and many traits ,such as leaf quality, yield, resistance and adaptability, still can't meet the demand. Therefore, it is very important to study the differences of traits and their genetic characteristics among different types.There are four purpose in this study. The first purpose analyzes the differences of the botany traits and the flavor matters to provide the genetic source of aroma for quality breeding. The second uses the mixed major-gene plus polygene inheritance model to study the inheritance of the main botany traits to reduce the difficulty and errors in selection. The third uses the molecular marker technology to select the belt of different culture spawns and provide a stable selection criteria for the tobacco breeding. The fourth analyze the genotypic differences to study the diversity and the relationship among different tobacco to provide the theoretical basis for breeding.Therefore, this study analyzes the phenotypic differences and the genetic differences among the representative varieties of the different types of tobacco, by observing the traits, detecting aroma substances and using diallel crossing test, cluster analysisthe, mixed major-gene plus polygene inheritance model, SRAP technology. The results are as follows:1) The differences of traits and aroma of different types of tobacco are analyzed and clustered into five groups by R factor cluster method based on 12 varieties; meanwhile, the 12 varieties are systematically clustered based on 32 traits. The result is similar to the practice.2) The mixed major-gene plus polygene inheritance model is used to analyze the inheritance of plant height in Nicotiana tabacum L. cross between flue-cured tobacco and burley tobacco, oriental tobacco, sun-cured tobacco. The results showed that the inheritance of plant height is accorded with the E1 model, and there were additive gene effect and dominant gene effect in the three cross combinations; the heritability of major genes for G-28×Qiancengta and G-28×Basma, were 71.60% and 88.55% respectively. The higher heritability will provide the theoretical basis for choosing the plant height at earlier generation. Meanwhile, this result shows that the mixed major-gene plus polygene inheritance model could be used in the inheritance study of quantitative characters of tobacco.3) The mixed major-gene plus polygene inheritance model is also used to analyze the inheritance of the main botanical traits, including pitch, leaf number, leaf length and leaf width etc., cross between flue-cured tobacco (G-28)and oriental tobacco (Basma). The results showed that the inheritance of pitch, leaf length and width are all accorded with the E1 model, the leaf number is accorded with the E6 model. The result would be used in tobacco breeding.4) SRAP technology is used to study the genetic differences among different types of tobacco, including flue-cured tobacco, oriental tobacco, maryland tobacco, burley tobacco, and air/sun cured tobacco, five pairs of primer combinations which can amplify characteristic bands has been screened. Among the five combinations, two of them (SF25*SR2 and SF3*SR26) can distinguish air-cured tobacco including maryland tobacco and Burley tobacco from the other cultivated forms; SF20*SR14 can distinguish sun cured tobacco including oriental tobacco and sun-cured tobacco; SF16*SR14 can distinguish flue-cured tobacco and air-cured tobacco, and SF22*SR14 can distinguish DBJ599 with specisl aroma and the other flue-cured tobacco.5) 8 varieties , which represent the different types of tobacco, are divided into 3 groups. I: G-28, II:DBJ599,MD40,By21, III: Basma,Sumsun,XNS,QCT. The cluster analysis result es consistant with experience evatuation.6) Anorthogonal design was used to optimize a ILP-PCR system with 5 factors (DNA, Mg2+, dNTP, primer and Taq polymerase) at 4 levels.The result showed the optimized ILP-PCR system for Nicotiana tabacum L. was: 2uL10×PCRbuffer, 20ng template DNA, Mg2+ 2.0mmol/L, dNTP 150umol/L, primer 0.3umol/L, Taq DNA polymerase 1 U in a total of 20uL reactionsolution. Each factor had different effecton on the results of PCR. Taq DNA polymerase had the greatest effect, while DNA concentration had the least. The effection of Taq DNA polymerase, primer concentration and dNTP concentration all reached significant level.