Multiple displacement amplification as a pre-polymerase chain reaction (pre-PCR) to detect ultra low population of Ralstonia solanacearum (Smith 1896) Yabuchi et al. (1996).

Aims:  To develop a reliable and sensitive protocol for detection of Ralstonia solanacearum using MDA-PCR (Multiple displacement amplification–PCR amplification). Methods and Results:  MDA-PCR technique was performed on pure cell lysates as well as soil samples. Pure cell lysate as well as that of soil DNA was used as template in MDA reaction. MDA of template DNA was carried out in the presence of sample buffer, reaction buffer and enzyme mix (Φ 29 DNA polymerase and random hexamers). The MDA amplified DNA was used for PCR amplification using R. solanacearum -specific PCR primers. MDA-PCR could detect as low as 1 colony forming unit (CFU ml−1) of bacteria within 8 h including DNA isolation. Conclusion:  MDA followed by standard PCR facilitated the detection of pathogen from very low count samples. The method is of great importance in managing the brown rot disease of potato. Significance and Impact of study:  The ultrasensitive detection technique developed in the present study is sensitive and speedy enough to be included into integrated wilt disease control programmes.