Integrated management of ratoon stunting disease of sugarcane: detection of Clavibacter xyli subsp. xyli, causing ratoon stunting disease of sugarcane using PCR [polymerase chain reaction]
1998
Opina, N.L.
The sensitivity of polymerase chain reaction (PCR) to detect Clavibacter xyli subsp. xyli (Cxx), the causal bacterium of the ratoon stunting disease (RSD) of sugarcane in fivrovascular fluid (FVF) was compared with dot blot Immunoassay (DBIA) and evaporative binding enzyme-linked immunosorbent assay (EB ELISA). PCR proved to be the most sensitive assay which could detect Cxx at 1 x 10 sup-7 dilutions from FVF samples and Cxx isolates. DBIA and EB ELISA, on the other hand, could detect Cxx at 10 x 10 sup-3 and 1 x 10 sup-2, respectively from FVF and at 1 x 10 sup-4 and 1 x 10 sup-3, respectively using Cxx isolate 267. All the sugarcane samples obtained from VMC Bacolod [Victorias Mill Co., Negros Oriental, Philippines], Camarines Sur, and IPB [Institute of Plant Breeding], UPLB, Los Baños [Laguna, Philippines] were positive to Cxx using PCR [polymerase chain reaction] while 10 of the 24 FVF samples from La Carlota were negative to Cxx. Not all of the samples had consistent reactions to DBIA and EB ELISA. Crude samples which exhibited positive/negative reactions in earlier tests became positive to all tests after the samples were centrifuged. These inconsistent reactions obtained from DBIA and EB ELISA were confirmed using PCR. Efficiency, sensitivity, and reliability of each of the methods depended on how the samples were extracted and prepared for assay. PCR was the most sensitive assay but needed a highly specific primer and a PCR machine. EB ELISA and DBIA were more convenient and practical, as these could handle a very large number of samples in one testing. Therefore, Cxx should be detected using serological techniques and samples that show in consistent reactions should be further confirmed using PCR.
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