Differences Of Potassium Accumulation During Mature Period And Diversity Of Rhizosphere Microorganisms In Different Flue-cured Tobacco Varieties

In order to explore the relationship between potassium accumulation and rhizosphere microbial diversity in flue-cured tobacco,the experiment was carried out at the zhengzhou science park of henan agricultural university in 2015-2016.Different flue-cured tobacco varieties(ND202,K326,NC89)were used as experimental materials,and the accumulation and distribution of potassium during mature period in flue-cured tobacco varieties,the expression differences of uptake transporter gene related to potassium,secretion of root exudates as well as physical and chemical properties,enzymatic activity,microbial diversity of rhizosphere soil were studied.The main results are as follows:Analysis of differences in accumulation ability of tobacco per plant maturity on potassium(K)shows that,ND202 was the strongest,the whole plant K accumulation reached 10.18 g,was significantly higher than that of K326(5.35 g)and NC89(4.85 g).In maturity,the potassium content of the ND202 upper leaves,middle leaves,lower leaves and stem was significantly higher than that of K326 and NC89,and the dry matter accumulation in the middle and lower leaves of ND202 also is more than that of K326 and NC89.The detection root exudates of the three varieties in mature period shows there are 19 kinds of common root exudates between the three varieties,of which are 11 kinds of organic acid.NC89,K326,ND202 have been detected the relative content of organic acids in root exudates were 68.94%,65.82%,81.80%,respectively.The study on physical and chemical properties of rhizosphere soil,changes of soil enzyme activities and root physiology in mature stage of different varieties in the process of growth and development shows that,ND202 has higher root fresh weight,root dry weight,root volume and the root activity.In the whole growth process of flue-cured tobacco,The content of available K in rhizosphere soil of NC89 and K326 showed a trend of increasing gradually,while the content of available potassium in the rhizosphere soil of ND202 reached the maximum in the prosperous period,lower than non rhizosphere soil in mature stage,significantly lower than other varieties.The relative expression of potassium channels and transporters in different flue-cured tobacco cultivars during ripening stage shows that,The relative expression of K channel gene Nt KC1,NTORK1 and NKT1 in flue-cured tobacco root was significantly higher than that in leaves,and it was the highest in the root of ND202.The potassium channel gene Nt TPK1 mainly expresses in the leaves,and the expression in the root was less.In the same part,the expression of ND202 was the highest,and the expression of K326 was the lowest.K transporter gene Nt HAK1 expresses in tobacco leaves and roots.There was significant difference among varietie in the same part,K transporter gene Nt KT12 expresses in tobacco leaves and roots,but less expressed in roots.There were significant differences in the expression of K related genes in different parts of flue-cured Tobacco.I11umina high throughput sequencing technology was used to analyze the soil microbial diversity in mature flue-cured tobacco,results shows that,at the phylum level,in the rhizosphere soil of flue-cured tobacco,the relative abundance of acid bacteria and thick wall was lower than that of non rhizosphere soil,and the relative abundance of Proteobacteria,actinomyces,TM7,OD1,BHI80-139,WPS-2,Bacteroides sp.,Pseudomonas aeruginosa,Pseudomonas aeruginosa,was higher than that of the non rhizosphere soil;at the phylum level,the diversity of rhizosphere microorganwasms was also different among the varieties.The relative abundance of actinomycetes in the rhizosphere soil of ND202 was higher than that of those in the Rhizosphere.At the genus level,the relative abundance of the genus bacillus,Lactococcus lactwas spp.,Pseudomonas aeruginosa,Brochothrix,Arthrobacter and other five genera of different varieties of flue-cured tobacco in the rhizosphere soil was lower than that of non rhizosphere soil,while the relative abundance of the genus Streptomyces,Lentz's genus,sphingolipids Aeromonas spp.,gas micro and other four in the rhizosphere soil was higher than that of non rhizosphere soil;in the genus level,rhizosphere microbial diversity differents between varieties in rhizosphere soil,relatively abundance of the Kawastobacter genus,Pseudomonas and other sphingolipids in ND202 rhizosphere soil was higher than other varieties,while that of Steroidobacter in ND202 rhizosphere soil was significantly lower than the other varieties.In non rhizosphere soil,the relative abundance of Nitrification spirillum and Steroidobacter in ND202 rhizosphere soil was significantly lower than that of other species,while the relative abundance of Flavwasolibacter was significantly higher than that of other species.The correlation analysis of the comparative abundance of some bacteria in the rhizosphere soil and rhizosphere nutrition,root potassium uptake showed that the comparative contents of organic acids secreted by the roots expressed a significant positive correlation with the accumulation of potassium while a significant negative correlation with effective K+ content.The comparative content of organic acids in the root exudates had a extremely significant positive correlation with the comparative abundance of Kaistobacter and sphingomonadales,and a significant positive correlation with the comparative abundance of Iamia.There was a significant positive correlation between the accumulation of potassium in the whole plant and the comparative abundance of the genus Escherichia,and had a significant positive correlation with the comparative abundance of Iamia.The potassium accumulation of flue-cured tobacco at maturation stage was not only related to the uptake and transport of potassium in different cultivars,but also the potassium status of rhizosphere soil,the comparative content of organic acids in root secretion,the comparative abundance of rhizosphere microorganisms,roots and potassium distribution in tobacco plant.The interaction of comparative content of organic acids in root secretion,the comparative abundance of rhizosphere microorganisms and effective potassium contents in rhizosphere soils affected the uptake of potassium by flue-cured tobacco in maturation stage.