Identification of a virulence  tal  gene in the cotton pathogen,  Xanthomonas citri  pv.  malvacearum  strain Xss-V 2 –18

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Background

Bacterial blight of cotton (BBC), which is caused by the bacterium Xanthomonas citri pv. malvacearum ( Xcm), is a destructive disease in cotton. Transcription activator-like effectors (TALEs), encoded by tal-genes, play critical roles in the pathogenesis of xanthomonads. Characterized strains of cotton pathogenic Xcm harbor 8–12 different tal genes and only one of them is functionally decoded. Further identification of novel tal genes in Xcm strains with virulence contributions are prerequisite to decipher the Xcm-cotton interactions.

Results

In this study, we identified six tal genes in Xss-V ₂–18, a highly-virulent strain of Xcm from China, and assessed their role in BBC. RFLP-based Southern hybridization assays indicated that Xss-V ₂–18 harbors the six tal genes on a plasmid. The plasmid-encoded tal genes were isolated by cloning BamHI fragments and screening clones by colony hybridization. The tal genes were sequenced by inserting a Tn 5 transposon in the DNA encoding the central repeat region (CRR) of each tal gene. Xcm TALome evolutionary relationship based on TALEs CRR revealed relatedness of Xss-V ₂–18 to MSCT1 and MS14003 from the United States. However, Tal2 of Xss-V ₂–18 differs at two repeat variable diresidues (RVDs) from Tal6 and Tal26 in MSCT1 and MS14003, respectively, inferred functional dissimilarity. The suicide vector pKMS1 was then used to construct tal deletion mutants in Xcm Xss-V ₂–18. The mutants were evaluated for pathogenicity in cotton based on symptomology and growth in planta. Four mutants showed attenuated virulence and all contained mutations in tal2. One tal2 mutant designated M2 was further investigated in complementation assays. When tal2 was introduced into Xcm M2 and expressed in trans, the mutant was complemented for both symptoms and growth in planta, thus indicating that tal2 functions as a virulence factor in Xcm Xss-V ₂–18.

Conclusions

Overall, the results demonstrated that Tal2 is a major pathogenicity factor in Xcm strain Xss-V ₂–18 that contributes significantly in BBC. This study provides a foundation for future efforts aimed at identifying susceptibility genes in cotton that are targeted by Tal2.

Related collections

Most cited references 66

Record: found
Abstract: found
Article: not found

Xanthomonas AvrBs3 family-type III effectors: discovery and function.

Jens Boch, Ulla Bonas (2010)

Xanthomonads are bacterial plant pathogens that cause diseases on many plant species, including important crops. Key to pathogenicity of most Xanthomonas pathovars is a Hrp-type III secretion (T3S) system that translocates effector proteins into plant cells. Within the eukaryotic cell, the effectors are thought to perform a variety of tasks to support bacterial virulence, proliferation, and dissemination. We are only beginning to understand the host targets of different effectors. The largest effector family found in Xanthomonas spp. is the AvrBs3/PthA or TAL (transcription activator-like) family. TAL effectors act as transcriptional activators in the plant cell nucleus. Specificity of TAL effectors is determined by a novel modular DNA-binding domain. Here, we describe the discovery of TAL effectors and their structure, activity, and host targets.

0 comments Cited 307 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Structural basis for sequence-specific recognition of DNA by TAL effectors.

Dong Hong Deng, Chuangye Yan, Xiaojing Pan … (2012)

TAL (transcription activator-like) effectors, secreted by phytopathogenic bacteria, recognize host DNA sequences through a central domain of tandem repeats. Each repeat comprises 33 to 35 conserved amino acids and targets a specific base pair by using two hypervariable residues [known as repeat variable diresidues (RVDs)] at positions 12 and 13. Here, we report the crystal structures of an 11.5-repeat TAL effector in both DNA-free and DNA-bound states. Each TAL repeat comprises two helices connected by a short RVD-containing loop. The 11.5 repeats form a right-handed, superhelical structure that tracks along the sense strand of DNA duplex, with RVDs contacting the major groove. The 12th residue stabilizes the RVD loop, whereas the 13th residue makes a base-specific contact. Understanding DNA recognition by TAL effectors may facilitate rational design of DNA-binding proteins with biotechnological applications.

0 comments Cited 199 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Os8N3 is a host disease-susceptibility gene for bacterial blight of rice.

Bing Yang, Akiko Sugio, Frank F. White (2006)

Many bacterial diseases of plants depend on the interaction of type III effector genes of the pathogen and disease-susceptibility genes of the host. The host susceptibility genes are largely unknown. Here, we show that expression of the rice gene Os8N3, a member of the MtN3 gene family from plants and animals, is elevated upon infection by Xanthomonas oryzae pv. oryzae strain PXO99(A) and depends on the type III effector gene pthXo1. Os8N3 resides near xa13, and PXO99(A) failed to induce Os8N3 in rice lines with xa13. Silencing of Os8N3 by inhibitory RNA produced plants that were resistant to infection by strain PXO99(A) yet remained susceptible to other strains of the pathogen. The effector gene avrXa7 from strain PXO86 enabled PXO99(A) compatibility on either xa13- or Os8N3-silenced plants. The findings indicate that Os8N3 is a host susceptibility gene for bacterial blight targeted by the type III effector PthXo1. The results support the hypothesis that X. oryzae pv. oryzae commandeers the regulation of otherwise developmentally regulated host genes to induce a state of disease susceptibility. Furthermore, the results support a model in which the pathogen induces disease susceptibility in a gene-for-gene manner.

0 comments Cited 176 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Contributors

Gongyou Chen: gyouchen@sjtu.edu.cn

Journal

Journal ID (nlm-ta): BMC Microbiol

Journal ID (iso-abbrev): BMC Microbiol

Title: BMC Microbiology

Publisher: BioMed Central (London )

ISSN (Electronic): 1471-2180

Publication date (Electronic): 15 April 2020

Publication date PMC-release: 15 April 2020

Publication date Collection: 2020

Volume: 20

Electronic Location Identifier: 91

Affiliations

[1 ]School of Agriculture and Biology, Shanghai Jiao Tong University/Key Laboratory of Urban Agriculture by the Ministry of Agriculture, Shanghai, 200240 China

[2 ]GRID grid.16821.3c, ISNI 0000 0004 0368 8293, State Key laboratory of Microbial Metabolism, School of life Science and Biotechnology, , Shanghai Jiao Tong University, ; Shanghai, 200240 China

Article

Publisher ID: 1783

DOI: 10.1186/s12866-020-01783-x

PMC ID: 7160923

PubMed ID: 32293266

SO-VID: e9c437cc-27d5-4c2c-b842-29c7c6279561

License:

Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

History

Date received : 24 December 2019

Date accepted : 5 April 2020

Funding

Funded by: FundRef http://dx.doi.org/10.13039/501100001809, National Natural Science Foundation of China;

Award ID: 31830072, 31230059

Award Recipient : Gongyou Chen

Custom metadata

ScienceOpen disciplines: Microbiology & Virology

Keywords: bacterial blight of cotton,xanthomonas citri pv. malvacearum,transcription-activator-like effector,virulence

Data availability:

ScienceOpen disciplines: Microbiology & Virology

Keywords: bacterial blight of cotton, xanthomonas citri pv. malvacearum, transcription-activator-like effector, virulence