Studying Of The Screening Of Potassium-rich Flue-cured Tobaccos And Bioinformatics Changes Of NHX Genes

ABSTRACT Tobacco is widely cultivated as an important economic crop,improving the potassium content of tobacco leaf in China is a task that is currently urgently needed.It is of great significance to select potassium-rich genotypes.However,there has not been a method batch-selecting individuals with high potassium potential accurately and conveniently.NHX(Na+(K+)H+ transporter)has been studied as a salt-resistant gene.However,many studies have found that this gene can also allow plants to absorb large amounts of accumulated potassium.The NHX gene in tobacco is still rare.In this study,two generations of hybrid progeny populations were used as materials.Based on the rule of"potassium-enriched flue-cured tobacco is not tolerant to low potassium",the feasibility of screening high-potassium plants at seedling stage was studied,and the selection of potassium-rich flue-cured tobacco was provided,material.At the same time,the root morphology and root physiological parameters of the taxa were screened under different potassium supply conditions to verify the screening effect.Homologously cloned the NHX gene in tobacco,compared the gene changes in yellowing strains,and tried to explore the molecular reasons for the differences in potassium efficiency obtained by this screening method.The test results are as follows:(1)After the selected plants grow in the field,the potassium content in the middle leaves has a gradient rule between the categories.In chronological order,the potassium content in the middle leaves of the first category is over 2.0%,the second category.Most were in the 1.5-2.5%range,while the third category was mostly below 1.5%.It shows that the screening method has high accuracy and feasibility.(2)The sand culture experiment showed that the four strains and the eight strains have a certain degree of gradient as a whole.From A to E,the index related to the absorption of accumulated potassium by the root system is reduced.The potassium content of A6 was the highest under normal potassium treatment,and the potassium content of E7 was the lowest.A6 was 2.08 times that of E7.The reduction of A6 without exogenous potassium was the most obvious,which was a decrease of 55.56%.A6 and C1 had the largest root system under potassium treatment and had the highest reduction after potassium stress,which were reduced by 82%and 70%,respectively.The root activity was slightly different,but the range difference was 32.85 mg/g/h.A6,A5 Both Cl and K1 had higher root vigor and decreased under potassium stress,which were reduced by 33.71%,31.33%and 39.58%,respectively.A6,A5,C1,and A13 had more root cation exchange capacity under normal potassium supply and decreased more under potassium stress conditions,decreasing by 44.25%,40.38%,28.60%,and 23.71%,respectively.Root A6 and D5 had the highest ATPase activity,and A6,A5,and C1 showed the greatest decrease after potassium stress,which were 43.02%,48.14%,and 49.53%,respectively.Therefore,A6,A5,and C1 are typical potassium-rich strains.(3)The tobacco NHX gene was cloned from leaves of K326 and the selected yellow plant M1 to obtain two sequences ntNHX2,ntNHX3 and ntNHX2 ntNHX3,respectively.By comparison,the gene was highly conserved,and the identity of the four nucleotide sequences was 97.61%.The predicted secondary structures of the genes in the two leaves differ greatly.There are three differences in the predicted amino acid sequence,and the protein structure is different..However,the proteins that were edited were cell membrane fimbriae,functioning as receptors or transport,with 12 transmembrane regions and isoelectric point PI = 8.66.The group selected in this experiment had an overall gradient pattern in terms of potassium content,root morphology,and root physiological indicators,indicating that the selected yellow plants eventually caused leaf potassium due to differences in root characteristics and differences in potassium uptake.The difference in content.Therefore,this set of yellowing as an intuitive screening index for the population of high-potassium single-tree screening method,there is higher accuracy and feasibility,but the screening process is prone to errors and details of the errors,so the need Other accurate identification methods cooperate.The tobacco NHX gene has a small amount of nucleotide changes and amino acid changes in the yellowing strains compared to common genotypes of flue-cured tobacco,but whether these changes can actually exert more research on the molecular effects of tobacco absorbing and transporting potassium ions.