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United States Department of Agriculture

Agricultural Research Service

Research Project: DOMESTIC, EXOTIC, AND EMERGING DISEASES OF CITRUS, VEGETABLES, AND ORNAMENTALS (DEED) Title: Citrus huanglongbing shapes the structure of bacterial community associated with citrus roots

Authors
item Trivedi, Pankaj -
item Duan, Ping
item Wang, Nian -

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 2010
Publication Date: June 1, 2010
Citation: Trivedi, P., Duan, Y., Wang, N. 2010. Citrus huanglongbing shapes the structure of bacterial community associated with citrus roots. Applied and Environmental Microbiology.

Technical Abstract: To examine the effect of pathogen on the diversity and structure of plant associated bacterial community, we carried out a molecular based analysis using citrus and huanglongbing as host-disease model. 16S rDNA clone library analysis of the citrus roots revealed shifts in the microbial diversity in response to pathogen infection. The clone library of the uninfected root samples have majority of phylotypes showing similarity to well known plant growth promoting bacteria including Caulobacter, Burkholderia, Lysobacter, Pantoea, Pseudomonas, Stenotrophomonas, Bacillus and Paenibacillus. Infection by the Ca. L. asiaticus re-structured the native microbial community associated with citrus roots and led to the extinction of majority of phylotypes while promoting the growth of bacteria such as Methylobacterium and Sphingobacterium. In pairwise comparisons, uninfected clone library contained significantly higher 16S rDNA gene diversity as reflected in the higher Chao 1 richness estimations (P= 0.01) of 237.13 and 42.14 for uninfected and infected clone library, respectively. Similarly, the Shannon index of the uninfected clone library (4.46) was significantly higher as compared to infected clone library (2.61). Principal Coordinates Analysis revealed a clear separation between the two set of libraries. Quantitative PCR analysis revealed that the bacterial community does not only change qualitatively but also quantitatively. The relative proportions of different groups of bacteria changed significantly after pathogen infection. These data implicate that infection of plants by pathogen has a profound effect on the structure and composition of the plant associated bacterial community.

Last Modified: 12/18/2014
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