Research On Screening And Application Of Three Endophytic Bacteria From Flue-cured Tobacco

Endophytic bacteria carried by seeds can spread between different generations, within which the beneficial bacteria were equipped with a rather strong affinity ability,the so-called genetic bias, over a long period of co-evolution with its host, so that can greatly improve the vaccination rate, and lay a foundation for further research and application.Three ascendant endophytic bacteria from tobacco seeds of K326,Yunyan 87, NC82 and Xiangyan 3 was screened in this study, of which the biological characteristics, growth promoting properties,ability of heavy metals absorption and other applications were analyzed, and the results were as follows:1. Using Dilution separation,60 endophytic bacteria significantly different in Exterior morphological characteristics were isolated from the tobacco seeds of K326, Yunyan 87, NC82 and Xiangyan 3.According to their resistance to heavy metals, the ability to produce siderophores and the effect of growth promotion,strain K03, Y04 and N05 were selected. Through morphology and 16S rDNA.Determination, the similarity of the three endophytic bacteria between cinnamon Pseudomonas(P.fulva), habitat hibiscus Pseudomonas (P.hibiscicola), Montessori Pseudomonas (P.monteilii) reached 99%, respectively, the three bacteria were determined to be the genus Pseudomonas (Pseudomonas).Qualitative analysis correlated with growth-promoting biological characteristics of the strains were conducted, The results showed that the strain K03, Y04 and N05 plates can form a yellow halo on the CAS solid medium,the diameters of the halos were 13.3 mm,14.2 mm, 13.4 mm; The three strains possessed the ability of IAA secreting, ACC dehydrogenase production and growth promoting effects, Which K03 and N05 has dissolved phosphorus, Y04 and N05 can nitrogen, Between K03 and Y04 has the Releasing ability.3. Sand culture experiments were conducted to compare the influences of K03, Y04 and N05 on tobacco root growth, the results showed that compared to the control, K03, Y04, N05 can promote root activity of tobacco, increase superoxide dismutase (SOD) and over peroxidase (POD) enzyme activity. In addition, three endophytic bacteria also significantly increased tobacco root fresh weight, dry weight and total root surface area, wherein Y04 have an obvious influence on growth-promoting.4. Soil pot experiments were carried out to compare the effects of K03, Y04 and N05 on soil heavy metal content and the absorption of cadmium and lead in tobacco plant,It turned out that (1) Vaccinating K03 strains can decrease the content of acid extractable, reducible and oxidation state, inoculating Y04 and N05 help the Cd/Pb in soil transform from residual and reducible state to oxidation andacid extractable state.(2)Cd content of upper leaves, middle leaves, roots processed by K03 compared to the control reduced 16.54%, 16.88%,28.80%, respectively. Pb content decreased 49.80%,16.48%,13.50%. Y04 processed tobacco Cd content compared to the control in the upper leaves, middle leaves, roots increased 40.67%,19.16%,14.30%, respectively. Pb content in upper leaves, middle leaves reduced 38.35%,54.47%, and increased 20.11%in the roots; Cd content of N05 treated sample compared to the control increase 57%%,2.49%,13.07%in upper leaves, middle leaves, roots, Pb content of upper leaves, middle leaves reduced 34.13%,42.24%, Pb content of roots increased 9.88%.Overall, K03, Y04 and N05 vaccination into K326 was capable of promoting growth, but different strains performed discriminating absorption and accumulation of Cd/Pb in of K326.K03 strains can significantly reduce the content of Cd and Pb in upper leaves, central leaves and root of flue-cured tobacco, Y04, N05 strains can significantly reduce the content of Pb in the upper leaves, middle leaves,while significantly increased the Cd and Cd/Pb content in upper leaves, middle leaves and in root system.The results of this paper can provide a reference for new ideas of endophytic bacteria in promoting tobacco growth and reduce the absorption of heavy metals and other studies.