| To screen varieties(strains) of tobacco genotypes in Potassium enrichment,discuss the hereditary features of Potassium properties, compare the effects of genetic and environmental factors on the capabilities of enrichment in Potassium and examine the differential expression of the key Potassium-absorption gene under different varieties(strains) and external environment. Two designed techniques, Oda and the pot methods, were used in this research. We investigated the content and the accumulation of Potassium in the leaves and the expression level of 5genes related to Potassium absorption in different tobacco parental lineages as well as their hybrids(F1).The results are as follows:1.The highest concentration of Potassium in leaves among 4 tobacco types is the burley tobacco, 2.66%, and 2nd is the flue-cured tobacco, between 1.34% and2.09%,among which K326,G80 and Nanjiang varieties have the higher level.The highest accumulation of potassium in leaves among 4 tobacco types may be the burley tobacco,burley with 1.46 g per strain, and flue-cured tobacco, between 0.99 g and2.92 g per strain, but the numble of species that have high accumulation of potassium is less, among which the higher level varieties in parents are Nanjiang3,G80,K326,GDH02.K326 and G80 are potassium absorption edge species in tobacco growth anaphasewith a higher rate of Potassium accumulation.The dominant varieties(strains) of Potassium above can be provided as predominant parents for breed improvement. The relative expression amount of NKT1 and NtHAK have positive correlation with the leaves Potassium feature in Oda and the tested gene.with the genetic engineering methods, NKT1 and NtHAK gene can be transducted into Tobacco cellsfor the improvement of the Potassium absorption.2.The hybrid combination,flue-cured tobacco Sun cured tobacco,flue-cured tobacco×flue-cured tobacco have the probability with higher concentration of Potassium in leaves.The F1 of flue-cured tobacco×flue-cured tobacco have a relatively stableconcentration of Potassium in leaves,of which the 76.19% hybrid off spring has a medium level concentration.G80× GDH02,HongDa×GDH02,K326×QinGeng and Va116×Maryland have higher level of Potassium content. 76.19% F1 of flue-cured tobacco and flue-cured tobacco has a higher level accumulation of Potassium in leaves, compared to other hybrid types.Half of the F1 between flue-cured tobacco and burley tobacco hybrid combination rank the first level,and the others second level.The hybrid combination of H80×TN90,Va116×TN90,HongDa×GDH02 and K326×QingGeng stem have the advantage in the accumulation of Potassium in leaves. Flue-cured tobacco hybrid F1 turn out to be positive in Potassium accumulation velocity and higher combination efficiency at maturation stage,such as Va116×QingGeng,H80A×TN90,G80×GDH02,K326×GDH02 and G80×Hongda. GDH02 and Hongda are the best parents for breeding in Potassium accumulation velocity.The analysis of hereditary capacity about hybrid combination of Potassium content suggests that the Potassium content character and the dominant Potassium content F1 mainly depends on the dominance effects and epistatic effectsas well as the inherent cause of the parental lineages.The expression level of NtHAK among tested5 genes,has a positive correlation to the leaves.Potassium content positive over-parent heterosis and mid-parent heterosis in hybridcombination Potassium content. So we arrival at a conclusion that the expression level of NtHAK in leaves may play a prominent role in Potassium content.3.As the concentration of the environmental potassium increases,the concentration and accumulation of potassium among tobacco strains in leaves are on the rise.When the concentration of the environmental potassium exceeds a certain degree,the trend will become slow.The potassium content in leaves of K326 and Maryland tobacco were at a higher level under the condition of field maturity and pot experiment.The rate of growth of the potassium content in leaves is not high when the potassium concentration continued to increase outside.The results indicate that these two tobacco strains may be resistant well to low potassium concentration;When K326×Maryland tobacco and Va116 × Maryland tobacco were under lowor high potassium environment,leaves have high potassium content,this result showed that high and low affinity to the potassium absorption system are equally important for the leaves.When H80 A, green stalks H80 A and green stem were under the condition of low potassium, potassium content of the leaves is not high, but with the rising of the concentrations of potassium, increase of the leaf potassium content is bigger, the two strains mainly exist low affinity of potassium absorption system in leaves compared with other tested strains.Tobacco varieties(strain) with different potassium stress,cumulative leaf potassium content, and the analysis of gene differencial expression showed that NKT1 expressed under four potassium stress showed similarities trends of hanging with testing strains leaf potassium content.Under the condition of medium and low potassium content,Nt KC1 showed little difference with the leaf content of testing tobacco strains;under the condition of control and low potassium content,NtTPK1 and NtHAK also showed little difference with the leaf content of testing tobacco strains,whereas under the four conditions, NTORK1 showed significant difference with testing tobacco strains.The result indicated that NtKC1 may belong to high potassium absorption affinity system,NtTPK1 and Nt HAK may belong to low affinity system.The expression of NKT1 in all tobacco has been increasing with the rising of the potassium content in leaf,but the changing trend of leaf potassium content from most tobacco strains had a negative correlation with the expression of NtTPK1 and NtHAK,but the changing trend of leaf potassium content from a very few of tobacco strains had a negative correlation with the expression of NTORK1 and NtKC1.We can speculate that they belong to different potassium absorption system, the former belongs to the low affinity absorption system while the latter belongs to the high affinity absorption system.The changing of trend in the leave potassium content from K326×QingGeng,Va116×Marylan,K326×Meitan big pretty smoke and Va116×Meitan big pretty smoke had the most obvious positive correlation with the change of NKT1 expression amount.Va116,Maryland,QingGeng,H80A×Maryl and H80A×QingGeng had obviously positive correlation with NTORK1,H80A×Meitan big pretty smoke and K326 stem had obviously positive correlation with NtTPK1;H80A and K326×Maryland had obviously positive correlation with NtKC1;Meitan big pretty smoke,K326×Maryl and Va116×QingGeng had obviously positive correlation with NtHAK.If the potassium concentration from external enviroment could be improved,increasing the count of gene expression with matching tabacco strains refered to above,which may be in favor of improving the potassium concentration of leaf.Of course, the direct evidence are needed through further study.
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