Comparative Genomics Analyses of Citrus-Associated Bacteria

Abstract

Xylella fastidiosa 9a5c (XF-9a5c) and Xanthomonas axonopodis pv. citri (XAC) are bacteria that infect citrus plants. Sequencing of the genomes of these strains is complete and comparative analyses are now under way with the genomes of other bacteria of the same genera. In this review, we present an overview of this comparative genomic work. We also present a detailed genomic comparison between XF-9a5a and XAC. Based on this analysis, genes and operons were identified that might be relevant for adaptation to citrus. XAC has two copies of a type II secretion system, a large number of cell wall-degrading enzymes and sugar transporters, a complete energy metabolism, a whole set of avirulence genes associated with a type III secretion system, and a complete flagellar and chemotatic system. By contrast, XF-9a5c possesses more genes involved with type IV pili biosynthesis than does XAC, contains genes encoding for production of colicins, and has 4 copies of Type I restriction/modification system while XAC has only one.

Genomic Insights into Xylella fastidiosa Interactions with Plant and Insect Hosts

“…A notable difference between Xanthomonas and Xylella genomes is size; X. fastidiosa shares * 74 % of its genome with Xanthomonas strains (Moreira et al 2004), but X. fastidiosa genomes range from 2.5 to 2.7 megabase pairs (Mb), the smallest Xanthomonas genome (X. albilineans) consists of 3.7 Mb and other genomes range from 4.5 to 5.5 Mb. Unlike X. fastidiosa, Xanthomonas ssp.…”

Different Profiles of the Negatively Stained Citrus Canker Bacterium Xanthomonas citri pv. citri Depending on Culture Media and Heavy Metal Stains

“…citri) is a pathogen of the Asiatic type of citrus canker (Schaad et al, 2005). As a gram negative bacterium, the pathogen has flagella and type IV fimbriae (Moreira et al, 2004). Fimbriae of plant pathogenic bacteria are involved in various functions: biofilm formation on the host surface, attachment to stomata and hydathodes, and twitching motility (Van Doorn et al, 2001).…”

Virulence strategies of phytopathogenic bacteria and their role in plant disease pathogenesis

“…This translocation system is considered as one of the simplest secretion pathway (Desvaux, 2004;Tseng et al, 2009). The T5SS translocation system is dedicated to transfer a single specific polypeptide known as the passenger domain in two step process (Moreira et al, 2004). The first step is mediated by a sec translocator across the inner membrane.…”

“…In Gram-negative bacteria, the virulence factors associated with T5SS passenger are numerous including biofilm formation, adhesins, toxins, enzymes production and cytotoxic activity (Leo at al., 2012;JacobDubuisson, 2013). Among the plant pathogenic Gramnegative bacteria that involve the T5SS secretion system as pathogenicity determinant include Xylella factidiosa, the causative agent of Pierce's disease (Igo et al, 2007), the Xanthomonads (Van Sluys et al, 2002;Moreira et al, 2004) and E. chrysanthemi (Tseng et al, 2009). …”