Genetic Differences Of Low Cadmium Accumulation In Tobacco Varieties

The influence of environmental factors on the genetic characteristics of tobacco leaf cadmium absorption and the key genes and their inheritance laws affecting the cadmium up take capacity of tobacco are mainly studied in this thesis.In order to explore the effects of cadmium uptake-related genes in different tobacco varieties,the pot experiment was used to analyze the cadmium content of the tobacco parent and its hybrid F1 generation and the expression of cadmium uptake-related genes in tobacco leaves.The main results are as follows:1.Defference analysis and cluster analysis of cadmium content in tobacco leaves at maturity of 15 tobacco varieties showed that there were significant differences in cadmium content among different tobacco varieties.The varieties with hight cadmium content are corker47,GDH94,Va116,Basma,GDH02.The second cadmium content is on G80,Yongsheng shaiyan,TN90,HongDa,Maryland smoke,Green Stalk,K326 and MeiDa,the lowest cadmium content is the lost type of Samsun and Daye in cluster analysis.The reason why NTPSC1 and NtGSH2 regulate the cadmium content tobacco in K326,MeiDa,Samsun,TN90,HongDa,G80 is they have a better positive effect on cadmium absorption of tobacco leaves,while NtHMA2 and NtNramp1 do not show obvious regularity,and the relative expression of NtNramp1 is small.2.F1 generation showed obvious heterosis.Among the 15 hybrid combinations,safflower Hongda ×MeiDa(73.16%)and G80×TN90(103.61%)have higher pro-inferiority,while K326× MeiDa(-78.07)and Samsun × G80(-56.43%)have lower pro-inferiority.Since the cadmium content of tobacco has a 40% mid-parental advantage and same even exhibit superhigh parental advantages,the heterosis of cadmium content on tobacco leaves can be used to reduce the cadmium content of tabacco.3.The cadmium content of safflower HongDa X Basma and HongDa X MeiDa are at a higher position in the hybrid variety with safflower HongDa as the Female parent,while the cadmium content of the hybrid combination with Samsun which has lower cadmium content as the female parent.Simultaneously,hybrid combination with G80 as the female parent,its cadmium content is the middle position.Although the male parent with Samsun is a cadmium-rich variety,the high cadmium content is not reflected in the hybridization combination.Meanwhile another hybrid combination of the large cadmium as a female large leaf tobacco did not consistently exhibit the dame trait,as the female parent.In summary the cadmium content of F1 is not a simple genetic or maternal trait,but is related to the inheritance of both parents.4.In the correlation analysis between the cadmium content of tobacco leaves and the four genes tested,the expression levels of NtPSC1 and NtGSH2 were positively correlated with the cadmium content in tobacco leaves.The relative expression of NtNramp1,NtPSC1 and NtGSH2 and hybrid cadmium content when they interacted with each other.5.The inheritance of tobacco cadmium traits is quantitatively inherited,whice is controlled by multiple genes and the environment.With the increase of cadmium of cadmium concentration in the environment the cadmium content of tobacco leaves increase,while the smallest increase is Samsun.At different concentrations,only the relative expression levels of cadmium uptake-related genes in NtNramp1 and NtHMA2were up-regulated,while there was no regularity in NtPSC1 and NtGSH2.The reason is due to the influence of the external cadmium environment on the expression of genes in the cadmium trait inheritace.