Construction Of A Molecular Genetic Linkage Map Of Tobacco Based On SRAP And ISSR Markers

A molecular genetic map Was constructed with a F₂ genetic mapping population from a cross of flue-cured tobacco varieties Tai yan 7 and burley tobacco varieties Burley 21 by using SRAP and ISSR polymorphism primers' PCR amplification and genetic linkage analysis. It is the first molecular genetic linkage map based on F₂ genetic mapping population crossing between flue-cured tobacco and Burley Tobacco in the world, Riching the types of genetic linkage map in tobacco ,and fundamental to gene mapping,QTL analysis and marker-assisted selection of important agronomic traits of tobacco. The major results are as follow:(1) with an 187 F₂ individuals from the cross of flue-cured tobacco varieties Tai yan 7 and burley tobacco varieties Burley 21 as genetic mapping population. Sequence-related Amplified Polymorphism (SRAP) and Inter-simple Sequence Repeat Polymorphism (ISSR) were used to construct a genetic linkage map in Tobacco.(2) From the tobacco genome , 58 SRAP primer pairs and 10 ISSR primers, which could reveal polymorphisms between Tai yan 7 and Burley 21, were screened out of 19×27 primer combinations of SRAP and 42 ISSR primers .(3) These markers generated 128 polymorphic bands in PCR amplification of the F₂ population. The average of polymorphic bands produced by one primer pair was 1.9, and the maximum was 6.(4) Using MAPMAKER / EXP Version3.0b and MapDraw V2.1, a linkage genetic map was constructed, which consisted of 92 SRAP markers and 20 ISSR markers distributed in 26 linkage groups(L0D≥3.0)and covered 1560. 2cM with an average distance of 18.1cM. Another 16 markers had not entered into linkage groups. The maximum distance between the marker was 48.6 cM, and the Minimum was 0 cM, the number of makers in each linkage group was between 2-20, the length of linkage group between 0-291.0cM. The distribution of Markers in the entire linkage group is uniform, no getting together phenomenon happened.(5) We also discussed the distortion problems in construction of a genetic linkage map of tobacco and its solutions in this study.