Man Jung Kang

Sensitive and Specific Detection of Xanthomonas oryzae pv. oryzae by Real-Time Bio-PCR Using Pathovar-Specific Primers Based on an rhs Family Gene

The present study describes bio-polymerase chain reaction (PCR) assays to detect bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae in rice. Successful control of X. oryzae. pv. oryzae requires a specific and reliable diagnostic tool. However, other X. oryzae pathovars are detected by currently available molecular and serological methods. In this study, SYBR Green real-time and conventional PCR primer sets were designed based on an rhs family gene of X. oryzae pv. oryzae KACC10331 because these genes are structurally diverse. The specificity of the primers was evaluated using purified DNA from 11 isolates of two X. oryzae pathovars, 21 other Xanthomonas species, and 4 other reference phytopathogenic bacteria and fungi. The assay was also able to detect at least two genome equivalents of cloned amplified target DNA using purified DNA. Thus, the SYBR Green real-time PCR-based method can be used for the rapid and specific detection of X. oryzae pv. oryzae and will potentially simplify and facilitate diagnosis and monitoring of this pathogen and guide plant disease management.

Quantitative Real-Time Polymerase Chain Reaction Assay for Detection of Pectobacterium wasabiae Using YD Repeat Protein Gene-Based Primers

The aim of this study was to develop a quantitative polymerase chain reaction (qPCR) assay for specific detection of Pectobacterium wasabiae using a primer pair based on the YD repeat protein gene for amplification of a 140-bp DNA fragment from infected wasabi (Wasabia japonica), a member of the crucifer family. The soft rot caused by P. wasabiae is an emerging disease that is present in many wasabi-producing areas. However, specific and reliable methods for identifying the pathogen are not available. Therefore, a qPCR primer set for accurate diagnosis of P. wasabiae was developed from publically available genome sequences. A SYBR Green qPCR primer set was designed based on a YD repeat protein gene of P. wasabiae WPP163 because it is known that this gene is structurally diverse among species, pathovars, or subspecies. The specificity of the primer set was evaluated using genomic DNA from 5 isolates of P. wasabiae, 5 different species of Pectobacterium, and 16 other pathogenic reference bacteria. The primer set used in the PCR assay successfully amplified a 140-bp amplicon for all five P. wasabiae strains. No amplification was obtained from 29 other pathogenic bacteria. The assay was also able to detect at least two genomic DNA, or 3 CFU per reaction, when using calibrated cell suspension.

Sensitive and specific detection of phaseolotoxigenic and nontoxigenic strains of Pseudomonas syringae pv. phaseolicola by TaqMan real-time PCR using site-specific recombinase gene sequences

Pseudomonas syringae pv. phaseolicola, the causative agent of halo blight, is the most important bacterial pathogen of bean. Both nontoxigenic (Tox(-)) and toxigenic (Tox+) strains of this pathogen cause halo blight in beans. However, nontoxigenic strains cannot be detected by currently available molecular and serological tools. In this study, a TaqMan probe and primer set were designed based on the phage integrase family site-specific recombinase of P. s. pv. phaseolicola 1448A because it is known that most site-specific recombinases are structurally and functionally diverse. The specificity of the probe and primers was evaluated using purified DNA from 29 isolates of 3 different pathovars of P. syringae. The probe and primer set were able to detect Tox(-) and Tox+ isolates of P. s. pv. Phaseolicola, but no other phytopathogenic bacteria. The assay was also able to detect at least 5 genome equivalents of cloned amplified target DNA, using purified DNA, or 7 colony forming unit (CFU) per reaction when using calibrated cell suspensions. Thus, the TaqMan real-time PCR-based method can be used for the rapid detection of both types of P. s. pv. Phaseolicola, and will potentially simplify and facilitate the diagnosis and monitoring of this pathogen, and guide plant disease management.

Rapid and Specific Detection of Burkholderia glumae in Rice Seed by Real-Time Bio-PCR Using Species-Specific Primers Based on an rhs Family Gene

In this study, we developed a reliable, quick, and accurate quantitative polymerase chain reaction (qPCR) assay to detect grain rot caused by Burkholderia glumae in rice seed. The control of bacterial grain rot is difficult, and the only practical methods for disease management rely on the use of pathogen-free seed, appropriate culture practices, and resistant cultivars. Therefore, the specific detection of this pathogen in seed is essential for effective control of the disease. However, other Burkholderia spp. are also detected by currently available molecular and serological methods. In this study, we exploited the available genome sequence information in public databases to develop specific PCR primers for accurate diagnosis of B. glumae. An SYBR Green real-time PCR primer set was designed based on the rhs family gene (YD repeat protein) of B. glumae BGR1 because these genes are structurally diverse. The specificity of the primers was evaluated using purified DNA from 5 isolates of B. glumae, 6 different species of Burkholderia, and 18 other reference pathogenic bacteria. The assay was able to detect at least one genome equivalent of cloned amplified target DNA using purified DNA or 1 CFU per reaction when using calibrated cell suspension. This method is rapid and reliable and has great potential for analyzing large numbers of samples.

PlantGI: a database for searching gene indices in agricultural plants developed at NIAB, Korea

The Plant Gene Index (PlantGI) database is developed as a web-based search system with search capabilities for keywords to provide information on gene indices specifically for agricultural plants. The database contains specific Gene Index information for ten agricultural species, namely, rice, Chinese cabbage, wheat, maize, soybean, barley, mushroom, Arabidopsis, hot pepper and tomato. PlantGI differs from other Gene Index databases in being specific to agricultural plant species and thus complements services from similar other developments. The database includes options for interactive mining of EST CONTIGS and assembled EST data for user specific keyword queries. The current version of PlantGI contains a total of 34,000 EST CONTIGS data for rice (8488 records), wheat (8560 records), maize (4570 records), soybean (3726 records), barley (3417 records), Chinese cabbage (3602 records), tomato (1236 records), hot pepper (998 records), mushroom (130 records) and Arabidopsis (8 records). Availability The database is available for free at http://www.niab.go.kr/nabic/.