Comparative and functional genomic analyses of the pathogenicity of phytopathogenXanthomonas campestrispv.campestris

Abstract

Xanthomonas campestris pathovar campestris (Xcc) is the causative agent of crucifer black rot disease, which causes severe losses in agricultural yield world-wide. This bacterium is a model organism for studying plant-bacteria interactions. We sequenced the complete genome of Xcc 8004 (5,148,708 bp), which is highly conserved relative to that of Xcc ATCC 33913. Comparative genomics analysis indicated that, in addition to a significant genomic-scale rearrangement cross the replication axis between two IS1478 elements, loss and acquisition of blocks of genes, rather than point mutations, constitute the main genetic variation between the two Xcc strains. Screening of a high-density transposon insertional mutant library (16,512 clones) of Xcc 8004 against a host plant (Brassica oleraceae) identified 75 nonredundant, single-copy insertions in protein-coding sequences (CDSs) and intergenic regions. In addition to known virulence factors, full virulence was found to require several additional metabolic pathways and regulatory systems, such as fatty acid degradation, type IV secretion system, cell signaling, and amino acids and nucleotide metabolism. Among the identified pathogenicity-related genes, three of unknown function were found in Xcc 8004-specific chromosomal segments, revealing a direct correlation between genomic dynamics and Xcc virulence. The present combination of comparative and functional genomic analyses provides valuable information about the genetic basis of Xcc pathogenicity, which may offer novel insight toward the development of efficient methods for prevention of this important plant disease.

The periplasmic binding protein NrtT affects xantham gum production and pathogenesis in Xanthomonas citri

“…6E). Since xantham gum production is directly related to the ability of the bacterium to infect, colonize and form biofilm 37, 38, we analyzed the production of biofilm by Xac::nrtT in comparison with X. citri after growth of the cells in polypropylene plates and adhesion in sweet orange leaves ( C. sinensis ). The results showed a reduction of 24% in the values of absorbance indicating the nrtT deletion also affected biofilm formation (Fig.…”

Glyceraldehyde-3-phosphate dehydrogenase of Xanthomonas campestris pv. campestris is required for extracellular polysaccharide production and full virulence

“…YP_242066.1) was assigned as a GAPDH (Qian et al, 2005), which displays 73 and 82 % identity and similarity, respectively, to the GAPDH encoded by the gapA gene of E. coli (NCBI Protein accession no. P0A9B2) (data not shown).…”

“…The ED pathway is implicated in the synthesis of xanthan gum (Hsu & Lo, 2003). Recently, we have determined the whole-genome sequence of Xcc strain 8004 (Qian et al, 2005). The genome data show that strain 8004 possesses genes encoding all of the enzymes involved in the glycolysis, ED, pentose phosphate and gluconeogenesis pathways (Qian et al, 2005).…”

“…Recently, we have determined the whole-genome sequence of Xcc strain 8004 (Qian et al, 2005). The genome data show that strain 8004 possesses genes encoding all of the enzymes involved in the glycolysis, ED, pentose phosphate and gluconeogenesis pathways (Qian et al, 2005). Interestingly, the genome contains only one predicted open reading frame (ORF) encoding a protein homologous to GAPDHs.…”

Regulation of the Type II Secretion Structural Gene xpsE in Xanthomonas campestris Pathovar campestris by the Global Transcription Regulator Clp

“…A mutant XC472 was identified for reduced virulence on cabbage with a Tn5 transposon insertion at the coding sequence of the clp gene [20]. Reverse transcription (RT)-PCR analysis using RNA isolated from XC472 and primers specific to the xpsE coding sequence indicated that transcription of the xpsE gene in the clp mutant was reduced significantly (data not shown).…”