Identification Of Granville Wilt (Ralstonia Solanacearum) Isolated From The Tobacco Soil And The Effect Of Sodium Borate On The Growth Of It

In this paper, Granville wilt, caused by bacterial pathogen Ralstonia solanacearum, which can severely limit tobacco(Nicotiana tabacum) production in the Tobacco-growing Area of China, was the research object.Fristly, a new method to separate and detect the bacteria quickly in the soil was established.The Effect of Sodium Borate on the Growth of it was the emphasis of the study. And the influence mechanism was also studied. And this paper wil provide the theory basis for the development of new type of soil improver.The main results of the paper were as follows:In order to establish a new method for rapidly and cheaply isolation and identification the viable cells of Ralstonia solanacearum E. F.Smith in White Burley soil, a semiselective medium (PCCG) and polymerase chain reaction (PCR) method were used to isolate the bacteria. And12strains were acquired. Then the strains were purified and identified by the internal transcribed spacer (ITS) region and blast in NCBI. The results showed that:the12strains were all homologous to R. solanacearum. which suggested that the method was suitable for the isolation and identification of R. solanacearum in soil. Finally, biovars of these strains were classified using Hayward’s classification criterion of R. solanacearum. The results showed that12strains belonged to biovar111.The possible relationship between boron and granville wilt was investigated in this study. Boron, an essential plant micronutrient, was effective in the form of borax for control of granville wilt caused by R. solanacearum in the culture medium, water or soil at30℃. The inhibition of R. solanacearum was closely correlated with boron concentrations in the same pH value of the solution. The growth of R. solanacearum was inhibited on potato sucrose solution supplemented with greater than or equal to5mmol/L of Borax. Boron at80mmol/L were the most effective in reducing growth of R.solanacearum in the sterilized water. Finally, Soil with80mg/kg Borax had the lowest number of R. solanacearum. These datum suggest that the growth of R. solanacearum could be significantly reduced by boron in low concentration, and R. solanacearum could be death because of high boron concentration.According to the results, the extracellular polysaccharide (EPS) of R. solanacearum was not suppressed significantly by Borax.And the intracellular proteins and extracellular proteins of R. solanacearum were influenced by the Borax.By the use of SDS-PAGE and Peptide Mass Fingerprinting (PMF), two different proteins were fround.They were related with the signal peptide.The two proteins may play an important role in the process of signal transduction.Sodium Borate influenced the activity of the pectinase and cellulose enzymes. With the borax concentration increased, the activity of the two proteins gradually decreased. And when the borax concentration was higher than2.0mmol/L,the two proteins were not detected.