• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.773-787
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• 2014

Bacterial pustule of soybean caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases in many areas where soybeans are grown. This study was carried out to evaluate the effect of cultivars, sowing date and cropping system on the suppression of soybean bacterial pustule in the field. One hundred soybean cultivars were screened for disease resistance against bacterial pustule in naturally infested field. Among them, fourteen cultivars including 'Pureun' were found to be high resistant. And thirty cultivars showed to be moderate resistant(less than 3% of diseased leaf area). When Soybean cultivar 'Taekwang' were sown in four different dates, May 25, June 5, June 15, and June 25, at 10 day-interval in Milyang, the diseased leaf area of bacterial pustule was 23.3%-25.7%, 14.7%-18.0%, 10.7%-12.8%, and 1.0%-2.7%, respectively. The lowest percentage of diseased leaf area was recorded in the plots sown on June 25, whereas the highest percentage of diseased leaf area was recorded in the plot sown on May 25. As sowing time was delayed, incidence of soybean bacterial pustule found to be comparatively reduced. From December in 2006 to June in 2007, we surveyed the pathogen population of soybean bacterial pustule in five cropping upland soils where soybean was cultivated. The survey result showed the bacterial pustule pathogens were detected from the all cropping soils. The pathogen populations of soybean bacterial pustule in soybean-barley and soybean-garlic cropping soil were significantly lower than that of the other cropping soils. In addition, the incidence of soybean bacterial pustule was decreased under the two cropping systems.

• Research in Plant Disease
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• v.21 no.1
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• pp.40-43
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• 2015

Bacterial pustule of soybean is caused by Xanthomonas axonopodis pv. glycines, one of the most important diseases in soybean. The symptom of bacterial pustule is mainly distributed around leaf veins. However, the reason has not been known. In order to determine pathosystem of bacterial pustule in leaf, soybean leaves were collected and observed using scanning electron microscopy (SEM) and light microscopy. Many hairs were observed at abaxial sides of the leaf, few hairs were observed at tissue around the leaf veins. In addition, unidentified bacterial cells and dusts at the no hair part near veins were observed. In the inoculation assays, the cells of X. axonopodis pv. glycines were observed near leaf veins. The imprint of underside of soybean leaves inoculated with X.axonopodis pv. glycines on PDA showed that the growth of bacteria around veins was observed but no bacterial growth at the part with leaf hairs. Our data demonstrated that soybean leaf hairs play an important role as a physical barrier for structural resistance of soybean against bacterial pustule pathogen.

• Research in Plant Disease
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• v.17 no.3
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• pp.317-325
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• 2011

Bacterial pustule of soybean (Glycine max) caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases of soybean in Korea, where it causes considerable yield loss. This study was carried out to develop yield prediction model for bacterial pustule by analyzing correlation between the percentage of diseased leaf area and yield. The severe disease incidence of soybean bacterial pustule caused yield losses by 19.8% in 2006 and 16.8% in 2007, respectively. Severity of bacterial pustule greatly affected on 100 seed weight and yield, but did not on stem length, number of branches per plant, number of pods per plant, number of seeds per plant. On the other hand, correlation coefficients between diseased leaf area and yield were $-0.93^*$('06) and $-0.77^*$('07), respectively. The regression equation obtained by analyzing correlation between the percentage of diseased leaf area and yield loss in 2006 and in 2007 was y = -3.2914x + 348.19($R^2$ = 0.8603) and y = -2.9671x + 302.08($R^2$ = 0.9411), respectively. These results will be helpful in estimating losses on a field-scale and thereby predicting the production of soybean.

• Journal of Crop Science and Biotechnology
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• v.11 no.4
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• pp.263-268
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• 2008

Bacterial leaf pustule (BLP) caused by Xanthomonas axonopodis pv. glycines is a serious disease to make pustule and chlorotic haloes in soybean [Glycine max (L). Merr.]. While inheritance mode and map positions of the BLP resistance gene, rxp are known, no sequence information of the gene was reported. In this study, we made five near isogenic lines (NILs) from separate backcrosses (BCs) of BLP-susceptible Hwangkeumkong $\times$ BLP-resistant SS2-2 (HS) and BLP-susceptible Taekwangkong$\times$ SS2-2 (TS) through foreground and background selection based on the four-stage selection strategy. First, 15 BC individuals were selected through foreground selection using the simple sequence repeat (SSR) markers Satt486 and Satt372 flanking the rxp gene. Among them, 11 BC plants showed the BLP-resistant response. The HS and TS lines chosen in foreground selection were again screened by background selection using 118 and 90 SSR markers across all chromosomes, respectively. Eventually, five individuals showing greater than 90% recurrent parent genome content were selected in both HS and TS lines. These NILs will be a unique biological material to characterize the rxp gene.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.193-202
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• 2007

Typical susceptible symptoms of the bacterial pustule disease caused by Xanthomonas axonopodis pv. glycines are pustule and chlorotic haloes that usually occur in leaves of Glycine max plants. The soybean genotype 'PI96188' showed an atypical response to all tested races X. axonopodis pv. glycines, accompanied with necrosis without chlorotic haloes on the underside of the necrotic symptoms. X. axonopodis pv. glycines 8ra grew to levels from 10 to 100 fold lower on PI96188 than on susceptible cultivar Jinjoo1, but 10-fold higher than on the resistant cultivar CNS. The chlorophyll content in PI96188 leaves remained unchanged until 12 days after bacterial infection. Ultrastructural observation showed that the infected leaf cells of PI96188 had intact normal chloroplasts compared to those of the susceptible cultivar Jinjoo1. Chloroplast degradation or the absence of chloroplasts in cells of the infected tissues was observed in Jinjoo1. Senescence-related ACS7 gene was significantly induced in PI96188 compared to those in Jinjoo1 at 2 days after inoculation. While photosynthesis-related rbcS gene showed the dramatic change in Jinjoo1, this gene was constitutively expressed in PI96188. However, expression of the defense-related genes, such as peroxidase and isoflavone synthase in the infected PI96188 leaves was similar to that in Jinjoo1. Together, these results suggest that the novel necrotic symptom in PI96188 is a kind of resistant response different from a typical hypersensitive response in the resistant genotypes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.5
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• pp.429-433
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• 2004

A single recessive gene, rxp, controls the bacterial leaf pustule (BLP) resistance in soybean and in our previous article, it has been mapped on linkage group (LG) D2 of molecular genetic map of soybean. A total of 130 recombinant inbred lines (RILs) from a cross between BLP-resistant SS2-2 and BLP-susceptible Jangyeobkong were used to identify molecular markers linked to rxp. Fifteen simple sequence repeat (SSR) markers on LG D2 were screened to construct a genetic map of rxp locus. Only four SSR markers, Satt135, Satt372, Satt448, and Satt486, showed parental polymorphisms. Using these markers, genetic scaffold map was constructed covering 26.2cM. Based on the single analysis of variance, Satt372 among these four SSR markers was the most significantly associated with the resistance to BLP. To develop new amplified fragment length polymorphism (AFLP) marker linked to the resistance gene, bulked segregant analysis (BSA) was employed. Resistance and susceptible bulks were made by pooling equal amount of genomic DNAs from ten of each in the segregating population. A total of 192 primer combinations were used to identify specific bands to the resistance, selecting three putative AFLP markers. These AFLP markers produced the fragment present in SS2-2 and the resistant bulk, and not in Jangyeobkong and the susceptible bulk. Linkage analysis revealed that McctEact97 $(P=0.0004,\;R^2=14.67\%)$ was more significant than Satt372, previously reported as the most closely linked marker.

• Journal of Crop Science and Biotechnology
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• v.10 no.3
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• pp.147-158
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• 2007

Xanthomonas axonopodis pv. glycines(Xag) is a pathogen that causes bacterial leaf pustule(BLP) disease in soybeans grown in Korea and the southern United States. Typical and early symptoms of the disease are small, yellow to brown lesions with raised pustules that develop into large necrotic lesions leading to a substantial loss in yield due to premature defoliation. After Xag infects PI 96188, only pustules without chlorotic haloes were observed, indicating the different response to Xag. To identify differentially expressed genes prior to and 24 hr after Xag inoculation to PI 96188 and BLP-resistant SS2-2, an oligonucleotide macroarray was constructed with 100 genes related to disease resistance and metabolism from soybean and Arabidopsis. After cDNAs from each genotype were applied on the oligonucleotide macroarrays with three replicates and dye swapping, 36 and 81 genes were expressed as significantly different between 0 hr and 24 hr in PI 96188 and SS2-2, respectively. Six UniGenes, such as the leucine-rich repeat protein precursor or 14-3-3-like protein, were selected because they down-regulated in PI 96188 and up-regulated in SS2-2 after Xag infection, simultaneously. Using tubulin and cDNA of Jangyeobkong(BLP-susceptible) as controls, the oligonucleotide macroarray data concurred with quantitative real-time RT-PCR(QRT RT-PCR) results in most cases, supporting the accuracy of the oligonucleotide macroarray experiments. Also, QRT RT-PCR data suggested six candidate genes that might be involved in a necrotic response to Xag in PI 96188.

• Korean Journal of Breeding Science
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• v.43 no.4
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• pp.282-287
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• 2011

Bacterial pustule (BP) is a leaf disease of soybean that is most common in Korea. Inoculation of 8ra, pathogen strain, to resistant and susceptible cultivars for finding the BP resistance gene (rxp) was much tried but the sequence of the exact gene is not found. This research performed in order to confirm the rxp gene near molecular marker by using the resistant and susceptible cultivars. Soybean BP resistance gene which related to region of near molecular marker could select the resistant cultivar. For the near molecular marker of rxp, reference genomics data available at sequenced Phytozome was used for designing molecular markers. The rxp was mapped between Satt372 and Satt486 on chromosome 17. According to previous study, rxp released in find mapping 7.2 Mbp to 7.3 Mbp on chromosome 17. In this study, we developed 3 random markers near from 6.6 Mbp to 7.3 Mbp on chromosome 17 identified to increase the genetic resolution of the rxp gene region using resistant and susceptible cultivars. Particularly, Rxp17-700 marker was mostly coincided resistance and susceptible genotype to rxp. This result suggests that Rxp17-700 marker will be more tightly linked to rxp gene.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.115-120
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• 2002

Xanthomonas axonopodis pv. glycines, the causal agent of bacterial pustule of soybean, induces hypersensitive response (HR) in a non-host plant, hot pepper (Capsicum annuum). A wild-type strain (8ra) and its non-patho-genic mutant (8-13) of X. axonopodis pv. glycines were inoculated into the pepper leaf tissues and their subcellular responses to the bacterial infections were examined by electron microscopy. Intrastructural changes related to HR were found in the leaf tissues infected with 8ra from 8 h after inoculation, characterized by separation of plasmalemma from the cell wall, formation of small vacuoles and vesicles, formation of cell wall apposition, and cellular necrosis. No such responses were observed in the tissues infected with the mutant. In 8ra, the bacterial cells were attached to the cell walls, with the cell wall material dissolved into and appearing to encapsulate the bacterial cells. The bacterial cells later became entirely embedded in the cell wall material. On the other hand, in 8-13, the bacterial cells were usually not attached tightly to the plant cell wall, and no or poor encapsulation of the bacteria by the wall material occurred, although these were encircled by rather loose wall materials at the later stages.

• Korean journal of applied entomology
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• v.16 no.1 s.30
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• pp.47-53
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• 1977

Bacterial diseases of soybean has been recognized as a limiting factor of soybean production in Korea as it was estimated to cause around 10 percent of yield losses annually. The purpose of the study is to obtain information on the diseases through proving the kinds of pathogens and epidemiology, The wire brush method and multineedle appeared to be the best way of inoculation under all circumstances. Wire brush method, especially, was effective in shortening the incubation period and manifesting the lesion development by introducing more inoculum per unit of area. In case of spray inoculation it was necessary to apply a small amount(1 : 1,000) of wetting agent, twin-20, otherwise it was unabled to produce the diseases under field conditions. Two kinds of bacterial diseases caused by Pseudomonas glycinea and Xanthomonas phaseoli var. sljense were found from surveyed areas in Kore. Wild fire disease on soybean caused by Pseudomonas tabaci had not detectable during the experiment although there were several reports on the disease from other countries. when the pathogens were introduced into sterile soil, bacterial leaf blight pathogen could exsisted until 30 days while bacterial pustule pathogen survived only 4 days under the natural conditions of later June. Both bacteria, however, could produce the disease after more than 10 months period of storage in refrigerator when they were exsisted in infected plant tissues. In warehouse, non-temperature controlled, the bacteria lose their infectability within 6 months period from October to April even though they exsisted in infected tissues. Surface infested seeds with the pathogens could not produced the diseases on seedling stages of soybean plants when the seeds were planted in sterile soil after inoculation by dipping the seeds into bacterial suspensions, although germination was depressed by the pathogens when the seeds were planted on agar media.