Analysis Of Genetic Models For Agronomic Traits And Chemical Indices And Constration Of Genetic Map In Flue-cured Tobacco

As a cash crop, tobacco plays an important role in the national economy in China. In tobacco breeding, agronomic and chemical properties of tobacco must be considered when the tobacco of high quality leaves is selected. Agronomic traits of tobacco mainly include plant height、stem girth、number of sheets、maximum leaf length、maximum width of blade and pitch,and chemical properties mainly refers to the nitrogen content、 nicotine content of potassium、Nicotine content、chlorine content and reducing sugar content. High quality tobacco has great relations with agronomic traits of tobacco, and the content and proportion of chemical constituents. The agronomic traits and chemical composition of tobacco mostly belong to quantitative traits, so it’s useful for selection methods and selection parents to research the genetic principles of agronomic traits and chemical indices. In this paper, Innovation3and Coker258are selected as hybrid combination, and we get4generations (P1, P2, F1, F2). Then agronomic and chemical characters of4generations were analyzed based on genetic model, and agronomic traits and chemical characters were studied. The aim is to obtain hybrid combinationability of parents and related genetic law, and it’s good to further research; with analyzing genetic model, a single one of F2population was used to construct a genetic map of tobacco. The results are as follows:(1) Plant height、stem girth、number of sheets、maximum leaf length、maximum width of blade are controlled by two of the additive dominant epistatic genes with additive dominant genes,namely E-1genetic model; pitch is controlled by two of additive dominance-epistssis major gene plus additive dominance epistasis polygene mixed inheritance model, namely E-0genetic model.(2) The genetic model of potassium content is C-0model, namely additive dominant epistatic by multiple genes, and the genetic model of the content of nicotine and chlorine is E-0, namely2of additive dominance epistatic major gene plus additive dominance epistatic gene the mixed genetic model, the best genetic model of nitrogen content is E-4, namely2peer major gene plus dominance polygene model; the best genetic model of reducing sugar content is E-2, namely2of additive dominance major gene plus additive dominance polygenes.(3) The studies showed that although the correlation coefficient of different traits is different, among them, both of two is positively correlated. Among them, the plant height is positively correlated with stem girth、maximum leaf length、maximum leaf width and pitch,and the distance reached significant level; stem girth is also positively correlated with maximum leaf length and maximum leaf width; the number of sheets is positively correlated with pitch, and the distance reached significant level; the maximum leaf length is positively correlated with maximum leaf width and pitch, and the distance reached significant level; it showed that various agronomic traits influence each other, work together to promote and grow together.(4) In tobacco, potassium andchlorine, nicotine, reducing sugar content are negatively correlated, and positively correlated with the nitrogen content, but do not reach significant level;is negatively related to the content of reducing sugar and nitrogen content,chlorine content, positively correlated with nicotine content; correlation coefficients of nicotine content and nitrogen content is positive, and the reducing sugar content correlation coefficient is negative, negative correlation; the correlation coefficient of nitrogen content and reducing sugar content is positive,positive correlation.(5) We used450pairs of SSR primers and1500pairs of SRAP primer to analyse combination of parents and F2group by SSR and SRAP markers,130polymorphism primers were selected in two parents, and55polymorphism primers were also selected in F2population. The proportion of polymorphic primers is very low. This may mainly due to both parents are the same type of flue-cured tobacco, and genetic differences is smaller. So the marker locus is litter on the genetic linkage map which we has constructed, and it doesn’t reached the expected target.