• The Plant Pathology Journal
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• v.38 no.5
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• pp.490-502
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• 2022

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) disease in rice (Oryza sativa L.) and it is among the most destructive pathogen responsible for severe yield losses. Potential bacterial biocontrol agents (BCAs) with plant growth promotion (PGP) abilities can be applied to better manage the BLB disease and increase crop yield, compared to current conventional practices. Thus, this study aimed to isolate, screen, and identify potential BCAs with PGP abilities. Isolation of the BCAs was performed from internal plant tissues and rhizosphere soil of healthy and Xoo-infected rice. A total of 18 bacterial strains were successfully screened for in vitro antagonistic ability against Xoo, siderophore production and PGP potentials. Among the bacterial strains, 3 endophytes, Bacillus sp. strain USML8, Bacillus sp. strain USML9, and Bacillus sp. strain USMR1 which were isolated from diseased plants harbored the BCA traits and significantly reduced leaf blight severity of rice. Simultaneously, the endophytic BCAs also possessed plant growth promoting traits and were able to enhance rice growth. Application of the selected endophytes (BCAs-PGP) at the early growth stage of rice exhibited potential in suppressing BLB disease and promoting rice growth.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.503-506
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• 2011

In order to analyze the resistant gene to Xanthomonas oryzae pv. oryzae in Korean native rices. Six Korean native rice varieties were crossed with IR-BB 101 contains Xa1 resistant gene and inoculated Japanese isolates IA(T7174). Cheonggunbyeo has Xa1 resistant gene only, and Yukseongjaerae, Agukdo, Heukpi and Icheon7ilchal have Xa1 and another one dominant gene. Ginggaragshare has Xa1 and another two dominant genes and two of those genes concerned complementary interaction against Japanese isolates IA(T7174).

• Biodesign
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• v.7 no.2
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• pp.35-37
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• 2019

Xanthomonas oryzae pv. oryzae (Xoo) is a plant pathogen, which causes a bacterial blight of rice. The bacterial blight is one of the most devastating diseases of rice in most of the rice growing countries and there is no effective pesticide against bacterial blight. The β-ketoacyl-acyl carrier protein synthase III (FabH) plays a key role in fatty acid synthesis (FAS) and is a promising drug target for the development of antibacterial agents. Xoo0878 gene, a fabH gene, from Xoo was cloned and its gene product Xoo0878 was expressed, purified and crystallized. Xoo0878 crystal diffracted to 2.1Å resolution and belonged to the triclinic space group P1, with unit-cell parameters a = 57.3Å, b = 64.7Å, c = 104.2Å and α = 81.6°, β = 84.7°, γ = 74.4°. There are four monomers in the asymmetric unit, with a corresponding crystal volume per protein weight of 2.65 ų Da^-1 and a solvent content of 53.6%. Xoo0878 structure will be useful to develop new antibacterial agents against Xoo.

• The Plant Pathology Journal
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• v.24 no.2
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• pp.143-151
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• 2008

To define the functions of the rpf genes in Xanthomonas oryzae pv. oryzae (Xoo), which regulates pathogenicity factors in Xanthomonas campestris pv. campestris (Xcc), marker-exchange mutants of each rpf gene were generated. When the mutants were inoculated on a susceptible cultivar, the lesion lengths caused by the rpfB, rpfC, rpfF, and rpfG mutants were significantly smaller than those caused by the wild type, whereas those caused by the rpfA, rpfD, and rpfI mutants were not. Several virulence determinants, including extracellular polysaccharide (EPS) production, xylanase production, and motility, were significantly decreased in the four mutants. However, the cellulase activity in the mutants was unchanged. Complementation of the rpfB and rpfC mutations restored the virulence and the expression of the virulence determinants. Expression analysis of 14 virulence genes revealed that the expression of genes related to EPS production (gumG and gumM), LPS (xanA, xanB, wxoD, and wxoC), phytase (phyA), xylanase (xynB), lipase (lipA), and motility (pitA) were reduced significantly in the mutants rpfB, rpfC, rpfF, and rpfG. In contrast, the expression of genes related to cellulase (eglxob, clsA), cellobiosidase (cbsA), and iron metabolism (fur) was unchanged. The results of this study clearly show that rpfB, rpfC, rpfF, and rpfG are important for the virulence of Xoo KACC10859, and that virulence genes are regulated differently by the Rpfs.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.177-183
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• 2013

Bacterial blight, an important and potentially destructive bacterial disease in rice caused by Xanthomonas oryzae pv. oryzae (Xoo), has recently developed resistance to the available antibiotics. In this study, mass spectrometry (MS)-based metabolite profiling and multivariate analysis were employed to investigate the correlation between timedependent metabolite changes and antimicrobial activities against Xoo over the course of Phomopsis longicolla S1B4 fermentation. Metabolites were clearly differentiated based on fermentation time into phase 1 (days 4-8) and phase 2 (days 10-20) in the principal component analysis (PCA) plot. The multivariate statistical analysis showed that the metabolites contributing significantly for phases 1 and 2 were deacetylphomoxanthone B, monodeacetylphomoxanthone B, fusaristatin A, and dicerandrols A, B, and C as identified by liquid chromatography-mass spectrometry (LC-MS), and dimethylglycine, isobutyric acid, pyruvic acid, ribofuranose, galactofuranose, fructose, arabinose, hexitol, myristic acid, and propylstearic acid were identified by gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling. The most significantly different secondary metabolites, especially deacetylphomoxanthone B, monodeacetylphomoxanthone B, and dicerandrol A, B and C, were positively correlated with antibacterial activity against Xoo during fermentation.

• Korean journal of applied entomology
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• v.23 no.1 s.58
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• pp.1-6
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• 1984

This study was conducted to investigate the incidence of bacterial leaf blight (BLB) in Milyang 30 which was previously considered to be resistant to Xanthomonas campestris pv. oryzae Seeds of Milyang 30 were collected from Suweon, Milyang and Haenam. When rice plants from different source were inoculated at the maximum tillering stage and flag leaf stage, reactions of Milyang 30 were consistant. The susceptibility of Milyang 30 was found to be due to infection with tome isolates in the pathotype II of X. campestris pv. oryzae.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1147-1150
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• 2011

Xanthomonas oryzae causes rice bacterial blight, which has been reported as one of the most destructive diseases of rice. Metabolites were identified through cheonggukjang, a traditional Korean fermented soybean product fermented by the Bacillus spp., to control the bacteria. HPLC, MS, and UPLC-Q-TOF-MS analyses were performed to identify metabolites responsible for antimicrobial activity. In this analysis, the m/z values of 253.0498, 283.0600, 269.0455, 992.6287, and 1,006.6436 were identified as daidzein, glycitein, genistein, surfactin B, and surfactin A, respectively. The levels of surfactin B and surfactin A were found to be high at 24 h (4.35 ${\mu}g$/ml) and 36 h (3.43 ${\mu}g$/ml) of fermentation, respectively.

• Proceedings of the Korean Society of Life Science Conference
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• 2002.03a
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• pp.90-90
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• 2002

• Research in Plant Disease
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• v.26 no.4
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• pp.195-201
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• 2020

Rice bacterial leaf blight (BLB) by Xanthomonas oryzae pv. oryzae (Xoo) is considered to be one of the major rice diseases steadily occurring around the rice-producing countries. In this study, we developed a recombinase polymerase amplification (RPA) assay for the rapid, convenient and specific diagnosis of Xoo by targeting Xoo-specific transposase A gene. As the target gene can be amplified in 10 min without DNA extraction process and special equipment for temperature control, RPA for BLB can be useful and practical component for on-site diagnosis.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.73-76
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• 1979

Two different isolates of Xanthomonas oryzae, KB 7785 of pathotype I and JN 7721 of pathotype III, that had been the most virulent isolates in the previous inoculation test, were reisolated from cultivar 'Milyang 23' and serially transferred to 10 times. They were inoculated to the 3 cultivars; 'Milyang 23' in Kinmaze group, 'Yushin' in Kogyoku group and 'Tongil' in Rantai-emas group cultivars. It was observed that the virulence of the isolate JN 7721 was more attenuated by the serial transfer on the Wakimoto's agar than the isolate KB 7785. The attenuation of virulence of the isolate JN 7721 was more significant at the cultivar 'Milyang23' than at the other cultivars. This suggests that the host-pathogen interactions and differences of the pathogenicity-maintenance ability among the pathogenic strains may be involved.