Limitation of detection techniques of Pantoea stewartii subsp. stewartii | เธ‚เน‰เธญเธˆเธณเธเธฑเธ”เธ‚เธญเธ‡เน€เธ—เธ„เธ™เธดเธ„เนƒเธ™เธเธฒเธฃเธ•เธฃเธงเธˆเน€เธŠเธทเน‰เธญ Pantoea stewartii subsp. stewartii

Pantoea stewartii subsp. stewartii (Pss) is a causal agent of corn wilt disease which transmits by insect and seed. This bacterium is in the listed of an important pest list in the quarantine regulation worldwide. Standard detection methods of this pathogen are growing on selective nigrosine medium, ELISA Agdia commercial test kit, PCR base test and substrate test with BioLog. In this experiment has shown the limiting of detection of ELISA method. Thirteen strains of bacteria were isolated from corn in Thailand with waving brown streak symptom resemble to stewart's wilt symptom. All bacteria grew well on LB medium plus 5 percent sodium chloride and also grew rapidly on nigrosine medium within 2 day. Whereas, Pss LMG2715, type strain took 5-7 day. Infected corn seedlings inoculated with these 13 bacterial strains were shown water-soaked symptom with lacking of hypersensitive reaction on tobacco. Most bacteria strains gave positive reaction with ELISA Agdia test kit for Pss with the exception of XE7 W001 and W002. Moreover many strains of bacteria also gave the positive PCR reaction with specific primer of 16S-23S rRNA/ITS and cpsD gene. However, Pss LMG2715 was the only one gave positive PCR reaction with hrpS gene primer. The 95 of carbon source substrates test on GN2 plate 84 percent similarity between Pss LMG2715 and Pss recorded in Biolog database. Whereas, Pss revealed 77 percent similarity with 10 bacterial isolated from infected corn. Corresponding to the comparison of AFLP DNA pattern 77 percent similarity could clustered tested bacteria into 6 groups. The Pss LMG2715 is separated out from the other. Therefore, the standard detection method especially, ELISA technique which is recommended as standard detection method for Pss is unable to give a specific detection for genus Pantoea stewartii subsp. stewartii. However, the PCR technique with specific primer is potentially method for Pss.