Genetic Analysis And Molecular Marker Development On Cembratrien-diols Content In Tobacco

Cembratrien-diols(CBT-diols)in tobacco is not only an important precursor substance of aroma components in tobacco leaves,but also has anti-cancer,antibacterial and other medicinal values.For the utilization of excellent resources,the CBT-diols content were determined using ultra high performance liquid chromatography(UPLC)by NC II with 10 flue-cured tobacco varieties and 25 F1 hybrids.And,the genetic effects of ?-CBT-diol content,?-CBT-diol content and CBT-diols were further analyzed.Furthermore,an F2 populations were developed by crossing between the high CBT-diols content germplasm Zhijinheidioba(maternal parent)and low CBT-diols content germplasm Mont Clame Brun(paternal parent).Genetic analysis was carried out using joint segregation analysis method with a mixed genetic model of major gene plus polygene.In order to identify QTLs correlated with CBT-diols content,the F2 populations were genotyped with SSR markers(Simple Sequence Repeats)and their CBT-diols content was determined using UPLC.Finally,222 tobacco germplasms,which were genetically stable under four environment conditions,were genotyped and subjected to CBT-diols content determination.Then,association analysis between SSR markers and CBT-diols content were performed to identify genetic markers correlated with CBT-diols content.The research results are as follows:1.The results of NCII showed significant additive variance and dominant variance of ?-CBT-diol,?-CBT-diol,as well as total CBT-diols,indicating that the tested traits were affected by both additive and dominant effects,but the influence was different.Zhongyan 102 had significant positive additive effect,while Cuibi1 and Zhongyan 86 had significant negative additive effect.The hybrid of Dabaijin 599×Honghuadajinyuan had extremely significant positive dominant effect,but the hybrids of G80×Jinxing 6007 and NC89×Jinxing 6007 had significant negative dominant effect.The narrow heritability of ?-CBT-diol,?-CBT-diol and total CBT-diols were 0.4029,0.3889 and 0.3994,respectively.In addition,significant positive correlation was observed between ?-CBT-diol,?-CBT-diol and total CBT-diols,and the correlation coefficients of the additive,dominance,genotype and phenotype were all over 0.98.2.Results from genetic analysis showed that ?-CBT-diol,?-CBT-diol and total CBT-diols of Zhijinheidiaoba × Mont Clame Brun combination are controlled by 2 pairs of additive-dominantepigenetic major genes plus additive-dominant-epigenetic polygenes(E-0).The additive effects of the two major genes are all positive,and the dominant effects are negative,and the additive and dominant effects of the first pair of major genes are stronger than those of the second pair.The heritability of the major genes of the 3 traits of CBT-diols content were 76.96%,76.88%,and 77.55%,the polygenic inheritance rate is less than 1%.In general,the genetic effect inheritance of 2 pairs of main genes was dominant in the three traits.Therefore,the content of CBT-diols was mainly affected by the genetic effect,and the genetic effect of the major genes were main genetic effect.3.Using 68 SSR markers,a tobacco linkage map covering 16 linkage groups and 703.4 c M was constructed.The number of markers per linkage group ranges from 2 to 9.The genetic distance between the markers was 1.1 to 36.2 c M,and the average distance was 10.34 c M.Using inclusive composite interval mapping(ICIM),12 QTLs correlated with CBT-diols content were detected and 4 QTLs were detected for ?-CBT-diol,?-CBT-diol and total CBT-diols,respectively.4 QTLs of each trait are in the same position as QTLs of other traits,located at LG2,LG8 a,LG23a and LG24,respectively,which can explain 14.3499~14.42% of the phenotypic variation of CBT-diols content traits.4.The CBT-diols content of 222 tobacco germplasms was planted in 4 environment.The results showed that the CBT-diols content in Xichang was generally higher than the CBT-diols content in Zhucheng.Germplasms with higher CBT-diols content in the above environment are CV87,CV58,Kang 88,CT709,Damo,NC82 and Yunyan 2,and germplasms with lower content are SPG-172,I-35,and Zhongyan 14,K730,Jintai 49,TI1112 and RG3414.5.The CBT-diols content in tobacco leaves was correlated with SSR molecular markers in 4 environments.A total of 37 SSR markers,which were distributed in 14 linkage groups,were detected in at least one environment and were significantly correlated with the CBT-diols content in tobacco leaves.The phenotypic variation efficiency of 37 association markers ranged from 1.87% to 22.17%.