Fan S.,State Key Laboratory for Biology of Plant Diseases and Insect PestsInstitute of Plant Protection |
Tian F.,State Key Laboratory for Biology of Plant Diseases and Insect PestsInstitute of Plant Protection |
Li J.,State Key Laboratory for Biology of Plant Diseases and Insect PestsInstitute of Plant Protection |
Chen H.,State Key Laboratory for Biology of Plant Diseases and Insect PestsInstitute of Plant Protection |
And 3 more authors.
Molecular Plant Pathology | Year: 2016
The targeting of bacterial type III secretion systems (T3SSs), which are critical virulence factors in most Gram-negative pathogens, is regarded as an alternative strategy for the development of novel anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc) are two of the most important bacterial pathogens on rice, which cause leaf blight and leaf streak diseases, respectively. To identify potential anti-virulence drugs against these two pathogens, we screened a library of plant phenolic compounds and derivatives for their effects on the Xoo T3SS. Ten of 56 compounds significantly inhibited the promoter activity of a harpin gene, hpa1. These inhibitors were further tested for their impact on the hypersensitive response (HR) caused by Xoo on non-host tobacco plants. The results showed that pretreatment of Xoo with TS006 (o-coumaric acid, OCA), TS010, TS015 and TS018 resulted in significantly attenuated HR without affecting bacterial growth or survival. In addition, Cya translocation assays demonstrated that the translocation of two T3 effectors was suppressed by the four inhibitors. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that mRNA levels of representative genes in the hrp (hypersensitive response and pathogenicity) cluster, as well as the regulatory genes hrpG and hrpX, were reduced by treatment with the four inhibitors, suggesting that expression of the Xoo T3SS was suppressed. The expression of other virulence factors was not suppressed, which indicated possible T3SS-specific inhibition. Finally, we demonstrated that these inhibitors reduced the disease symptoms of Xoo and Xoc on the rice cultivar (Oryza sativa) IR24 to varying extents. © 2016 BSPP AND JOHN WILEY & SONS LTD.
Zhou J.-N.,Guangdong Province Key Laboratory of Microbial Signals and Disease Control |
Zhang H.-B.,Institute of Molecular and Cell Biology 61 Biopolis Drive 138673Singapore |
Lv M.-F.,Guangdong Province Key Laboratory of Microbial Signals and Disease Control |
Chen Y.-F.,Guangdong Province Key Laboratory of Microbial Signals and Disease Control |
And 9 more authors.
Molecular Plant Pathology | Year: 2016
Dickeya zeae is a causal agent of rice root rot disease. The pathogen is known to produce a range of virulence factors, including phytotoxic zeamines and extracellular enzymes, but the mechanisms of virulence regulation remain vague. In this study, we identified a SlyA/MarR family transcription factor SlyA in D. zeae strain EC1. Disruption of slyA significantly decreased zeamine production, enhanced swimming and swarming motility, reduced biofilm formation and significantly decreased pathogenicity on rice. Quantitative polymerase chain reaction (qPCR) analysis confirmed the role of SlyA in transcriptional modulation of a range of genes associated with bacterial virulence. In trans expression of slyA in expI mutants recovered the phenotypes of motility and biofilm formation, suggesting that SlyA is downstream of the acylhomoserine lactone-mediated quorum sensing pathway. Taken together, the findings from this study unveil a key transcriptional regulatory factor involved in the modulation of virulence factor production and overall pathogenicity of D. zeae EC1. © 2016 BSPP AND JOHN WILEY & SONS LTD.
Sun S.,South China Agricultural University |
Sun S.,Guangdong Province Key Laboratory of Microbial Signals and Disease Control |
Shu C.W.,South China Agricultural University |
Shu C.W.,Guangdong Province Key Laboratory of Microbial Signals and Disease Control |
And 5 more authors.
Forest Pathology | Year: 2014
Bacteria wilt (BW) of Casuarina equisetifolia L. Johnson, caused by Ralstonia solanacearum (E. F. Smith) Yabuuchi, is one of the most important diseases of C. equisetifolia L. Johnson, the main coastal protective forest tree in southeast China. The resistance of 33 C. equisetifolia L. Johnson clones to BW was determined by means of hydroponic and pot inoculation methods with the suspension of R solanacearum (E. F. Smith) Yabuuchi as inocula in the two-step procedure. The results showed that clones FJ11 and FJ13 were highly resistant to BW with the lowest disease incidences of 10.8 and 15.8%, respectively, whereas clones FJ9 and GD15 were the most susceptible ones with the highest disease incidences of 100.0%. The analysis of AFLP markers was performed on clones FJ11, FJ13, FJ9 and GD15, and the results indicated that three DNA fragments E-AAA/M-CCG, E-AAG/M-CGC and E-AGG/M-CAA were found to be linked to the BW resistance. BLAST searches revealed that the first two fragments (GenBank accession numbers: KC111411 and KC135871) had no identities to any sequences, and the third one showed a high similarity to some sequences which code for heat shock protein. Taken together, the two resistant clones screened in our research were undoubtedly the valuable resistant resources of C. equisetifolia L. Johnson, and the three AFLP markers could be used in marker-assisted selection of C. equisetifolia L. Johnson in the future. © 2014 Blackwell Verlag GmbH.