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Draft:A Genetic Study on the Virulence Mechanism of Burkholderia glumae (2013)

A Genetic Study on the Virulence Mechanism of Burkholderia glumae and Rice Resistance to Bacterial Panicle Blight and Sheath Blight is a doctoral dissertation by Hari Sharan Karki, submitted to the Graduate School of Louisiana State University in 2013. The dissertation examines the virulence mechanisms of Burkholderia glumae, a pathogen that causes bacterial panicle blight in rice, and the development of resistance in rice plants against this disease and sheath blight.[1]

Background

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Burkholderia glumae is a bacterial pathogen responsible for bacterial panicle blight, which affects rice crops by causing grain rotting and seedling blight. The pathogen thrives in specific environmental conditions and is a seed-borne threat in rice-growing regions. Karki's dissertation investigates the molecular and genetic mechanisms that contribute to the virulence of this pathogen and explores strategies for breeding rice cultivars that exhibit resistance to bacterial panicle blight and sheath blight.[1]

Objectives

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The primary objectives of the study include:

  • Investigating the genetic factors that contribute to Burkholderia glumae's virulence.
  • Exploring the relationship between pigment production and virulence in the bacterium.
  • Examining the role of two-component regulatory systems (TCRS) in regulating virulence factors.
  • Identifying rice lines with resistance to bacterial panicle blight and sheath blight, through genetic breeding techniques.[1]

Methodology

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The research used mutagenesis and genetic manipulation techniques to study B. glumae. Transposon mutagenesis using mini-Tn5gus was employed to create mutant strains of B. glumae with altered pigment production. Pigmentation was used as an indicator of virulence, and several genes responsible for virulence, including those in the shikimate pathway, were identified.[1]

The study also focused on the PidS/PidR two-component regulatory system (TCRS), which controls several virulence-related phenotypes, such as toxoflavin production, a phytotoxin involved in B. glumae pathogenicity.[1]

To assess rice resistance, the study conducted breeding experiments that involved crossing different rice varieties, such as Bengal and LM-1, to develop new lines with enhanced resistance to bacterial panicle blight and sheath blight.[1]

Major findings

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  1. Pigment Production and Virulence: The study identified a link between pigment production and virulence in B. glumae. Mutations in genes such as aroA and aroB in the shikimate pathway resulted in a loss of pigmentation and a decrease in virulence.[1]
  2. PidS/PidR Two-Component Regulatory System: The research discovered the PidS/PidR two-component regulatory system, which regulates the production of toxoflavin and other virulence factors. Mutants deficient in PidS/PidR showed a reduction in toxoflavin production and exhibited less virulence in both rice and onion bulb assays.[1]
  3. Rice Resistance: The study led to the development of rice lines with enhanced resistance to bacterial panicle blight and sheath blight. LB-33, a recombinant inbred line derived from Bengal and LM-1, demonstrated resistance to these diseases and exhibited favorable agronomic traits such as increased yield.[1][2]

Applications

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The findings from this study are relevant to agricultural practices, particularly in rice-growing regions where bacterial panicle blight and sheath blight are prevalent. By identifying key genes associated with virulence and developing resistant rice lines, the research provides potential avenues for reducing crop losses caused by these diseases.

Impact and citations in other research

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The dissertation has been cited in various studies focused on plant pathology, bacterial virulence, and crop resistance. Research on Burkholderia glumae has continued to build on the genetic and molecular insights provided in this dissertation, particularly in the study of regulatory systems and pathogen-host interactions.[3][4][5]

References

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  1. ^ a b c d e f g h i Karki, Hari (2013-01-01). "A Genetic Study on the Virulence Mechanism of Burkholderia glumae and, Rice Resistance to Bacterial Panicle Blight and Sheath Blight". LSU Doctoral Dissertations. doi:10.31390/gradschool_dissertations.3491.
  2. ^ Chen, Ruoxi; Barphagha, Inderjit K.; Karki, Hari S.; Ham, Jong Hyun (2012-12-20). "Dissection of Quorum-Sensing Genes in Burkholderia glumae Reveals Non-Canonical Regulation and the New Regulatory Gene tofM for Toxoflavin Production". PLOS ONE. 7 (12): e52150. Bibcode:2012PLoSO...752150C. doi:10.1371/journal.pone.0052150. ISSN 1932-6203. PMC 3527420. PMID 23284909.
  3. ^ Shrestha, Bishnu K.; Karki, Hari Sharan; Groth, Donald E.; Jungkhun, Nootjarin; Ham, Jong Hyun (2016-01-14). "Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice". PLOS ONE. 11 (1): e0146764. Bibcode:2016PLoSO..1146764S. doi:10.1371/journal.pone.0146764. ISSN 1932-6203. PMC 4713167. PMID 26765124.
  4. ^ Wang, Sai; Nie, Wenhan; Yiming, Ayizekeranmu; Wang, Peihong; Wu, Yan; Huang, Jin; Ahmad, Iftikhar; Chen, Gongyou; Guo, Longbiao; Zhu, Bo (November 2022). "Next Generation Sequencing and Comparative Genomic Analysis Reveal Extreme Plasticity of Two Burkholderia glumae Strains HN1 and HN2". Pathogens. 11 (11): 1265. doi:10.3390/pathogens11111265. ISSN 2076-0817. PMC 9698995. PMID 36365016.
  5. ^ "LSU Scholarly Repository | Louisiana State University Research". repository.lsu.edu. Retrieved 2024-09-13.
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