Analysis And Gene Mapping Of Tobacco Fresh-Sweet And Fruity Aroma Mutants

Tobacco is an important economic crop and plays an important role in the national economy.Aroma is one of the most important traits of tobacco and closely related to the quality of tobacco.At present,China's tobacco leaves have problems such as insufficient aroma,low aroma quality and low industrial availability.The study accelerated the selection of aroma tobacco varieties,promoted the industrialization through studying aroma traits and laid a foundation for comprehensively analyzing the mechanism of tobacco aroma substances.In the paper,ten tobacco characteristic aroma mutants and the control cultivar Zhongyan 100 were observed by stereo microscope and the trichome densities were calculated;SSR markers were used to analyze SSR polymorphism and genetic diversity of tobacco mutants with different traits;Genetic analysis and gene mapping of two characteristic aroma mutants were carried out by constructing segregating populations and high-throughput whole-genome resequencing.1.The upper,middle and lower leaves of the mutants at the flowering stage were taken separately.They were observed by stereo microscope and the trichome densities were calculated.Compared with Zhongyan 100,most mutants showed significant difference or even highly significant difference in trichome density.Among them,the difference of the upper and middle leaves was the most significant,the highest trichome density was in mutant 1,and the lowest was in mutant 9.In different leaf positions,different mutants also showed significant difference or even highly significant difference in trichome density.2.SSR detection and sequence analysis were performed on 59 EMS-induced tobacco mutants and the control Zhongyan 100.A total of 126 alleles were amplified by 95 pairs of SSR primers,and an average of 1.33 alleles were detected by each primer pair;92 pairs of primers detected polymorphism,99 polymorphic bands were obtained,and the percentage of polymorphism was 78.57%;There were two types of difference in quantity and length of fragment.NTSYS2.10e was used for cluster analysis and tree diagram drawing,and the genetic variation between the recipient material Zhongyan 100 and59 mutant materials ranged from 0.44 to 1.00.3.To analyze the genetic mechanisms underlying the M87 mutant phenotype,the F₁ and F₂populations were made between sweetness aroma mutant?M87?and the wild-type cultivar K326.The aroma of each individual plants in the F₁ and F₂ population was investigated.The results showed that all of the F₁ plants had no special fragrance,similar to K326,while the segregation of the F₂ populations fit the expected ratio of 1:3,indicating that the mutant phenotype was controlled by a single recessive gene.The F₂ population was then used as gene mapping population,and the sweetness aroma mutant gene was preliminarily identified on chromosome 8 by whole-genome resequencing.Using SNP markers,M87 was eventually mapped between marker SNP08-1 and SNP08-4,with genetic distances of 1.8 c M and 3.6 c M,and a genetic linkage map was constructed.4.To analyze the genetic mechanisms underlying the M82 mutant phenotype,the F₁,F₂ and BC populations were made between fruity aroma mutant?M82?and the wild-type cultivar honghuadajinyuan?HD?.The aroma of each individual plants in the F₁ and F₂ population was investigated.The results showed that all of the F₁ plants had no special fragrance,similar to HD,while the segregation of the F₂population and the BC population fit the expected ratio of 1:3 and 1:1,respectively,indicating that the mutant phenotype was controlled by a single recessive gene.The F₂ population was then used as gene population,and the fruity aroma mutant gene was preliminarily identified on chromosome 14 by whole-genome resequencing.Using SNP markers,M82 was eventually mapped on the end of chromosome 14 and co-segregated with the marker SNP14-1,and a genetic linkage map was constructed.