Yong-Qiang He
Guangxi University
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Featured researches published by Yong-Qiang He.
Proceedings of the National Academy of Sciences of the United States of America | 2003
John Maxwell Dow; Lisa Crossman; Kim Findlay; Yong-Qiang He; Jia-Xun Feng; Ji-Liang Tang
The rpf gene cluster of Xanthomonas campestris pathovar campestris (Xcc) is required for the pathogenesis of this bacterium to plants. Several rpf genes are involved in the coordinate positive regulation of the production of virulence factors mediated by the small diffusible molecule DSF (for diffusible signal factor). RpfF directs the synthesis of DSF, and a two-component sensory transduction system comprising RpfC and RpfG has been implicated in the perception of the DSF signal and signal transduction. In L medium, rpfF, rpfG, rpfC, and rpfGHC mutants grew as matrix-enclosed aggregates, whereas the wild type grew in a dispersed planktonic fashion. Synthesis of the extracellular polysaccharide xanthan was required for aggregate formation. Addition of DSF triggered dispersion of the aggregates formed by the rpfF strain, but not those of rpf strains defective in DSF signal transduction. An extracellular enzyme from Xcc whose synthesis was positively controlled by the DSF/rpf system could disperse the aggregates produced by all rpf strains. The enzyme was identified as the single endo-β-1,4-mannanase encoded by the Xcc genome. This enzyme had no detectable activity against soluble xanthan. The endo-β-1,4-mannanase was required for the full virulence of Xcc to plants. On the basis of this model system, we propose that one role of the β-mannanase during disease is to promote transitions from an aggregated or biofilm lifestyle to a planktonic lifestyle in response to the DSF signal.
Molecular Microbiology | 2007
Robert P. Ryan; Yvonne Fouhy; Jean F. Lucey; Bo-Le Jiang; Yong-Qiang He; Jia-Xun Feng; Ji-Liang Tang; J. Maxwell Dow
Cyclic di‐GMP is a second messenger with a role in regulation of a range of cellular functions in diverse bacteria including the virulence of pathogens. Cellular levels of cyclic di‐GMP are controlled through synthesis, catalysed by the GGDEF protein domain, and degradation by EAL or HD‐GYP domains. Here we report a comprehensive study of cyclic di‐GMP signalling in bacterial disease in which we examine the contribution of all proteins with GGDEF, EAL or HD‐GYP domains to virulence and virulence factor production in the phytopathogen Xanthomonas campestris pathovar campestris (Xcc). Genes with significant roles in virulence to plants included those encoding proteins whose probable function is in cyclic‐di‐GMP synthesis as well as others (including the HD‐GYP domain regulator RpfG) implicated in cyclic di‐GMP degradation. Furthermore, RpfG controlled expression of a subset of these genes. A partially overlapping set of elements controlled the production of virulence factors in vitro. Other GGDEF‐EAL domain proteins had no effect on virulence factor synthesis but did influence motility. These findings indicate the existence of a regulatory network that may allow Xcc to integrate information from diverse environmental inputs to modulate virulence factor synthesis as well as of cyclic di‐GMP signalling systems dedicated to other specific tasks.
Journal of Bacteriology | 2008
Rong-Qi Xu; Servane Blanvillain; Jia-Xun Feng; Bo-Le Jiang; Xianzhen Li; Hong-Yu Wei; Thomas Kroj; Emmanuelle Lauber; Dominique Roby; Baoshan Chen; Yong-Qiang He; Guang-Tao Lu; Dong-Jie Tang; J Vasse; Matthieu Arlat; Ji-Liang Tang
Xanthomonas campestris pathovar campestris causes black rot, a vascular disease on cruciferous plants, including Arabidopsis thaliana. The gene XC1553 from X. campestris pv. campestris strain 8004 encodes a protein containing leucine-rich repeats (LRRs) and appears to be restricted to strains of X. campestris pv. campestris. LRRs are found in a number of type III-secreted effectors in plant and animal pathogens. These prompted us to investigate the role of the XC1553 gene in the interaction between X. campestris pv. campestris and A. thaliana. Translocation assays using the hypersensitive-reaction-inducing domain of X. campestris pv. campestris AvrBs1 as a reporter revealed that XC1553 is a type III effector. Infiltration of Arabidopsis leaf mesophyll with bacterial suspensions showed no differences between the wild-type strain and an XC1553 gene mutant; both strains induced disease symptoms on Kashmir and Col-0 ecotypes. However, a clear difference was observed when bacteria were introduced into the vascular system by piercing the central vein of leaves. In this case, the wild-type strain 8004 caused disease on the Kashmir ecotype, but not on ecotype Col-0; the XC1553 gene mutant became virulent on the Col-0 ecotype and still induced disease on the Kashmir ecotype. Altogether, these data show that the XC1553 gene, which was renamed avrAC(Xcc8004), functions as an avirulence gene whose product seems to be recognized in vascular tissues.
Journal of Bacteriology | 2007
Ke Wei; Dong-Jie Tang; Yong-Qiang He; Jia-Xun Feng; Bo-Le Jiang; Guang-Tao Lu; Baoshan Chen; Ji-Liang Tang
The MarR family of transcriptional regulators of bacteria are involved in the regulation of many cellular processes, including pathogenesis. In this work, we have demonstrated genetically that hpaR (hpa, hrp associated), which encodes a putative MarR family regulator, is involved in the hypersensitive response (HR), pathogenicity, and extracellular protease production of the phytopathogenic bacterium Xanthomonas campestris pathovar campestris. A mutation in hpaR resulted in complete loss of virulence in the host plant cabbage, a delayed and weakened HR in the nonhost plant pepper ECW-10R, and an increase in extracellular protease production. Detection of the beta-glucuronidase activity of a plasmid-driven hpaR promoter-gusA reporter revealed that the expression of hpaR is positively controlled by HrpG and HrpX and is suppressed in rich medium while being strongly induced in minimal and hrp-inducing media and inside the host. These findings indicate that hpaR belongs to the hrpG and hrpX regulon and that HrpX regulates the extracellular protease production via hpaR in X. campestris pv. campestris.
Genome Biology | 2007
Yong-Qiang He; Liang Zhang; Bo-Le Jiang; Zheng-Chun Zhang; Rong-Qi Xu; Dong-Jie Tang; Jing Qin; Wei Jiang; Xia-Xia Zhang; Jie Liao; Jin-Ru Cao; Sui-Sheng Zhang; Mei-Liang Wei; Xiao-Xia Liang; Guang-Tao Lu; Jia-Xun Feng; Baoshan Chen; Jing Cheng; Ji-Liang Tang
BackgroundXanthomonas campestris pathovar campestris (Xcc) is the causal agent of black rot disease of crucifers worldwide. The molecular genetic diversity and host specificity of Xcc are poorly understood.ResultsWe constructed a microarray based on the complete genome sequence of Xcc strain 8004 and investigated the genetic diversity and host specificity of Xcc by array-based comparative genome hybridization analyses of 18 virulent strains. The results demonstrate that a genetic core comprising 3,405 of the 4,186 coding sequences (CDSs) spotted on the array are conserved and a flexible gene pool with 730 CDSs is absent/highly divergent (AHD). The results also revealed that 258 of the 304 proved/presumed pathogenicity genes are conserved and 46 are AHD. The conserved pathogenicity genes include mainly the genes involved in type I, II and III secretion systems, the quorum sensing system, extracellular enzymes and polysaccharide production, as well as many other proved pathogenicity genes, while the AHD CDSs contain the genes encoding type IV secretion system (T4SS) and type III-effectors. A Xcc T4SS-deletion mutant displayed the same virulence as wild type. Furthermore, three avirulence genes (avrXccC, avrXccE1 and avrBs1) were identified. avrXccC and avrXccE1 conferred avirulence on the hosts mustard cultivar Guangtou and Chinese cabbage cultivar Zhongbai-83, respectively, and avrBs1 conferred hypersensitive response on the nonhost pepper ECW10R.ConclusionAbout 80% of the Xcc CDSs, including 258 proved/presumed pathogenicity genes, is conserved in different strains. Xcc T4SS is not involved in pathogenicity. An efficient strategy to identify avr genes determining host specificity from the AHD genes was developed.
Molecular Plant-microbe Interactions | 2009
Wei Jiang; Bo-Le Jiang; Rong-Qi Xu; Jun-Ding Huang; Hong-Yu Wei; Guo-Feng Jiang; Wei-Jian Cen; Jiao Liu; Ying-Ying Ge; Guang-Hua Li; Li-Li Su; Xiao-Hong Hang; Dong-Jie Tang; Guang-Tao Lu; Jia-Xun Feng; Yong-Qiang He; Ji-Liang Tang
Xanthomonas campestris pv. campestris is the pathogen of black rot of cruciferous plants. The pathogenicity of the pathogen depends on the type III secretion system (T3SS) that translocates directly effector proteins into plant cells, where they play important roles in the molecular interaction between the pathogen and its hosts. The T3SS of Xanthomonas spp. is encoded by a cluster of hypersensitive response and pathogenicity (hrp) genes. It has been demonstrated that the expression of hrp genes and some type III secreted (T3S)-effector genes is coactivated by the key hrp regulatory protein HrpX. The regulation by HrpX can be mediated by the binding of HrpX protein to a cis-regulatory element named the plant-inducible promoter (PIP) box present in the promoter region of HrpX-regulated genes. A genome screen revealed that X. campestris pv. campestris 8004 possesses 56 predicted genes with the PIP box. Nine of these genes have been shown to encode T3S effectors, Hrp, and Hrp-associated proteins. In this study, we employed an established T3S effector translocation assay with the hypersensitive-reaction-inducing domain of X. campestris pv. campestris AvrBs1 as a reporter to characterize the remaining 47 genes with the PIP box and showed that 6 of them, designated as XopXccE1, XopXccP, XopXccQ, XopXccR1, XopXccLR, and AvrXccB, harbor a functional translocation signal in their N-terminal regions, indicating that they are T3S effectors of X. campestris pv. campestris. We provided evidence to demonstrate that all these effectors are expressed in an HrpX-dependent manner and their translocation into plant cells relies on the translocon protein HrpF and the chaperone HpaB. Mutational analyses demonstrated that all these effectors, except AvrXccB, are individually required for full virulence and growth of X. campestris pv. campestris in the host plant Chinese radish.
Journal of Bacteriology | 2005
Dong-Jie Tang; Yong-Qiang He; Jia-Xun Feng; Bao-Ren He; Bo-Le Jiang; Guang-Tao Lu; Baoshan Chen; Ji-Liang Tang
Disruption of ppsA, a key gene in gluconeogenesis, of Xanthomonas campestris pv. campestris resulted in the failure of the pathogen to grow in medium with pyruvate or C4-dicarboxylates as the sole carbon source and a significant reduction in virulence, indicating that X. campestris pv. campestris possesses only the malic enzyme-PpsA route in gluconeogenesis, which is required for virulence.
Molecular Plant-microbe Interactions | 2005
Dong-Jie Tang; Xiang-Jiang Li; Yong-Qiang He; Jia-Xun Feng; Baoshan Chen; Ji-Liang Tang
Zur is a regulator of the high-affinity zinc uptake system in many bacteria. In Xanthomonas campestris pv. campestris 8004, a putative protein encoded by the open reading frame designated as XC1430 shows 42% amino acid similarity with the Zur of Escherichia coli. An XC1430-disrupted mutant 1430nk was constructed by homologous suicide plasmid integration. 1430nk failed to grow in rich medium supplemented with Zn2+ at a concentration of 400 microM and in nonrich medium supplemented with Zn2+ at a concentration of 110 microM, whereas the wild-type strain grew well in the same conditions. In rich medium with 400 microM Zn2+, 1430nk accumulated significantly more Zn2+ than the wild-type strain. 1430nk showed a reduction in virulence on the host plant Chinese radish (Raphanus sativus L. var. radiculus Pers.) and produced less extracellular polysaccharide (EPS) than did the wild-type strain in the absence of added zinc. These results revealed that XC1430 is a functional member of the Zur regulator family that controls zinc homeostasis, EPS production, and virulence in X. campestris pv. campestris.
Molecular Plant-microbe Interactions | 2009
Dong-Liang Huang; Dong-Jie Tang; Qing Liao; Xiao-Qian Li; Yong-Qiang He; Jia-Xun Feng; Bo-Le Jiang; Guang-Tao Lu; Ji-Liang Tang
In bacteria, Zur is a key regulator for zinc homeostasis. Our previous work has shown that, in the phytopathogen Xanthomonas campestris pv. campestris, in addition to regulating zinc homeostasis, Zur is essential for full virulence. Here, we demonstrate that the X. campestris pv. campestris Zur is involved in hypersensitive response (HR) and positively regulates the transcription of hrpA to hrpF operons and hrpX but not hrpG. Constitutively expressing hrpX but not hrpG in the zur mutant could bypass the requirement of Zur for the expression of hrpA to hrpF operons and the induction of wild-type HR, indicating that Zur controls the expression of hrp cluster via hrpX. Promoter-gusA reporter and semiquantitative reverse-transcription polymerase chain reaction analyses revealed that HrpG controls the expression of hrpX and HrpX regulates the expression of all the six hrp operons (hrpA to hrpF) in X. campestris pv. campestris.
Molecular Plant-microbe Interactions | 2008
Nai-Xia Chao; Ke Wei; Qi Chen; Qing-Lin Meng; Dong-Jie Tang; Yong-Qiang He; Guang-Tao Lu; Bo-Le Jiang; Xiao-Xia Liang; Jia-Xun Feng; Baoshan Chen; Ji-Liang Tang
RsmA is an RNA-binding protein functioning as a global post-transcriptional regulator of various cellular processes in bacteria and has been demonstrated to be an important virulence regulator in many animal bacterial pathogens. However, its function in other phytopathogenic bacteria is unclear, except for the Erwinia carotovora RsmA, which acts as a negative virulence regulator. In this work, we investigated the function of the rsmA-like gene, named rsmA(Xcc), of the phytopathogen Xanthomonas campestris pv. campestris. Deletion of rsmA(Xcc) resulted in complete loss of virulence on the host plant Chinese radish, hypersensitive response on the nonhost plant pepper ECW-10R, and motility on the surface of an agar plate. The rsmA(Xcc) mutant displayed a significant reduction in the production of extracellular amylase, endoglucanase, and polysaccharide, but a significant increase in intracellular glycogen accumulation and an enhanced bacterial aggregation and cell adhesion. Microarray hybridization and semiquantitative reverse-transcription polymerase chain reaction analysis showed that deletion of rsmA(Xcc) led to significantly reduced expression of genes encoding the type III secretion system (T3SS), T3SS-effectors, and the bacterial aggregate dispersing enzyme endo-beta-1,4-mannanase. These results suggest that rsmA(Xcc) is involved in the control of various cellular processes, including pathogenesis of X. campestris pv. campestris.