Dataset Information

Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis.

ABSTRACT: Response of bacterial pathogen to environmental bacteria and its host is critical for understanding of microbial adaption and pathogenesis. Here, we used RNA-Seq to comprehensively and quantitatively assess the transcriptional response of Acidovorax avenae subsp. avenae strain RS-1 cultivated in vitro, in vivo and in co-culture with rice rhizobacterium Burkholderia seminalis R456. Results revealed a slight response to other bacteria, but a strong response to host. In particular, a large number of virulence associated genes encoding Type I to VI secretion systems, 118 putative non-coding RNAs, and 7 genomic islands (GIs) were differentially expressed in vivo based on comparative genomic and transcriptomic analyses. Furthermore, the loss of virulence for knockout mutants of 11 differentially expressed T6SS genes emphasized the importance of these genes in bacterial pathogenicity. In addition, the reliability of expression data obtained by RNA-Seq was supported by quantitative real-time PCR of the 25 selected T6SS genes. Overall, this study highlighted the role of differentially expressed genes in elucidating bacterial pathogenesis based on combined analysis of RNA-Seq data and knockout of T6SS genes.

SUBMITTER: Li B

PROVIDER: S-EPMC4099980 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis.

Li Bin B Ibrahim Muhammad M Ge Mengyu M Cui Zhouqi Z Sun Guochang G Xu Fei F Kube Michael M

Scientific reports 20140716

Response of bacterial pathogen to environmental bacteria and its host is critical for understanding of microbial adaption and pathogenesis. Here, we used RNA-Seq to comprehensively and quantitatively assess the transcriptional response of Acidovorax avenae subsp. avenae strain RS-1 cultivated in vitro, in vivo and in co-culture with rice rhizobacterium Burkholderia seminalis R456. Results revealed a slight response to other bacteria, but a strong response to host. In particular, a large number o ...[more]

PMID: 25027476

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Project description:Determining how a bacterial pathogen responds to its host and other bacterial species by altering gene expression is key to understand its pathogenesis and environmental adaption. Here, we used RNA-Seq to comprehensively and quantitatively assess the transcriptional response of the rice bacterial pathogen Acidovorax avenae subsp. avenae strain RS-1 cultivated in vitro, in vivo and in co-culture with rice rhizobacterium Burkholderia seminalis R456. Results revealed a surprisingly large number of regulatory differences between these conditions indicating adaptation of A. avenae subsp. avenae to specific ecological conditions. In particular, a number of potential virulence factors such as type 3 secretion system proteins were specifically expressed under in vivo conditions, whereas genes whose protein products are involved in inter-bacterial interaction such as auxin efflux carrier, small mechanosensitive ion channel protein, and ureidoglycolate hydrolase were among those specifically up-regulated under co-culture conditions. In addition, global genomic analysis of strain RS-1 identified 406 putative non-coding (nc) RNA genes. Interestingly, 8 ncRNA genes that were uniquely expressed under in vivo may be linked to pathogenicity while 4 ncRNA genes that were uniquely expressed under coculture conditions may be involved in adaption to co-cultivation with B. seminalis. Expression data obtained by RNA-Seq were also confirmed for selected genes by quantitative real-time PCR and two-dimensional gel electrophoresis as well as knockout analysis. Aaa strain RS-1 and B. seminalis strain R456 was isolated from diseased rice plants (Li et al., 2011; Xie et al., 2011) and rice rhizosphere (Zhang et al., 2007; Li et al., 2011), respectively, in our previous studies, and were stored in 20-30% sterile glycerol at -80°C. The samples of Aaa strain RS-1 for in vitro and in vivo analysis were prepared as described before (Ibrahim et al., 2012). The co-culture analysis of Aaa strain RS-1 with B. seminalis strain R456 were conducted according to Ruiz et al. (2009) and Di Cagno et al. (2009). Briefly, Aaa strain RS-1 and B. seminalis strain R456 was inoculated and incubated in chambers of a double culture vessel apparatus separated by a 0.4-μm membrane filter (Millipore Isopore™). In order to avoid the possible contamination during in vivo and co-culture operation, all bacterial samples were further confirmed based on the sequence analysis of 16S-rRNA (Li et al., 2011). Then samples were processed for RNA harvesting, mRNA purification and cDNA synthesis.

Project description:Sugarcane (Saccharum spp.) is an important cash crop for production of sugar and bioethanol. Red stripe caused by Acidovorax avenae subsp. avenae (Aaa) is a disease that occurs in numerous sugarcane-growing regions worldwide. In this study, 17 strains of Aaa were isolated from 13 symptomatic leaf samples in China. Nine of these strains produced white-cream colonies on nutrient agar medium while the other eight produced yellow colonies. In pairwise sequence comparisons of the 16S-23S rRNA internally transcribed spacer (ITS), the 17 strains had 98.4-100% nucleotide identity among each other and 98.2-99.5% identity with the reference strain of Aaa (ATCC 19860). Three RFLP patterns based on this ITS sequence were also found among the strains of Aaa obtained in this study. Multilocus sequence typing (MLST) based on five housekeeping genes (ugpB, pilT, lepA, trpB, and gltA) revealed that the strains of Aaa from sugarcane in China and a strain of Aaa (30179) isolated from sorghum in Brazil formed a unique evolutionary subclade. Twenty-four additional strains of Aaa from sugarcane in Argentina and from other crops worldwide were distributed in two other and separate subclades, suggesting that strains of A. avenae from sugarcane are clonal populations with local specificities. Two strains of Aaa from China (CNGX08 forming white-cream colored colonies and CNGD05 forming yellow colonies) induced severe symptoms of red stripe in sugarcane varieties LC07-150 and ZZ8 but differed based on disease incidence in two separate inoculation experiments. Infected plants also exhibited increased salicylic acid (SA) content and transcript expression of gene PR-1, indicating that the SA-mediated signal pathway is involved in the response to infection by Aaa. Consequently, red stripe of sugarcane in China is caused by genetically different strains of Aaa and at least two morphological variants. The impact of these independent variations on epidemics of red stripe remains to be investigated.

Dataset Information

Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis.

Publications

Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis.

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