The Genus Xanthomonas

Starr, Mortimer P.

doi:10.1007/978-3-662-13187-9_62

Cited by 63 publications

(38 citation statements)

References 110 publications

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“…In this case, only one of a possible eight intermediates would have had these properties. Second, xanthomonadins are membrane bound (35); thus, one would not expect biosynthetic intermediates to be freely diffusible. Third, cross-feeding is usually observed due to overproduction (by a donor mutant strain) of a biosynthetic intermediate because of a mutation later in the pathway than the mutation of the recipient (pigB mutant) (18).…”

Section: Discussionmentioning

confidence: 99%

“…Many of the phytopathogenic xanthomonads are disseminated on seed (22), and at least some of these pathogens survive and multiply as epiphytes prior to plant infection (13,35). Two common traits of Xanthomonas spp.…”

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confidence: 99%

“…are the production of yellow pigments (xanthomonadins) and extracellular polysaccharide slime (EPS) (32). The xanthomonadins are yellow, membrane-bound, brominated aryl-polyene pigments unique to the genus Xanthomonas (35). Thus, these pigments are commonly used as chemotaxonomic (2,36) and diagnostic (32) markers.…”

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pigB determines a diffusible factor needed for extracellular polysaccharide slime and xanthomonadin production in Xanthomonas campestris pv. campestris

Poplawsky

Chun

1997

J Bacteriol

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Seven xanthomonadin transcriptional units (pigA through pigG) were identified by transposon saturation mutagenesis within an 18.6-kbp portion of the previously identified 25.4-kbp pig region from Xanthomonas campestris pv. campestris (strain B-24). Since marker exchange mutant strains with insertions in one 3.7-kbp portion of pig could not be obtained, mutations in this region may be lethal to the bacterium. Complementation analyses with different insertion mutations further defined and confirmed the seven transcriptional units. Insertional inactivation of one of the transcriptional units, pigB, resulted in greatly reduced levels of both xanthomonadins and extracellular polysaccharide slime, and a pigB-encoding plasmid restored both traits to these strains. pigB mutant strains could also be restored extracellularly by growth adjacent to strains with insertion mutations in any of the other six xanthomonadin transcriptional units, the parent strain (B-24), or strains of five different species of Xanthomonas. Strain B-24 produced a nontransforming diffusible factor (DF), which could be restored to pigB mutants by the pigB-encoding plasmid. Several lines of evidence indicate that DF is a novel bacterial pheromone, different from the known signal molecules of Vibrio, Agrobacterium, Erwinia, Pseudomonas, and Burkholderia spp.Members of the genus Xanthomonas are distributed worldwide and are the causal agents for disease for at least 124 monocot and 268 dicot plant hosts (20). Many of the phytopathogenic xanthomonads are disseminated on seed (22), and at least some of these pathogens survive and multiply as epiphytes prior to plant infection (13,35). Two common traits of Xanthomonas spp. are the production of yellow pigments (xanthomonadins) and extracellular polysaccharide slime (EPS) (32). The xanthomonadins are yellow, membrane-bound, brominated aryl-polyene pigments unique to the genus Xanthomonas (35). Thus, these pigments are commonly used as chemotaxonomic (2, 36) and diagnostic (32) markers. Although the biological role of xanthomonadins is not well understood, a correlation between these pigments and protection against photobiological damage has been observed (14). A correlation between EPS production and virulence has been widely reported for Xanthomonas campestris (7,9,33,38,39).In a previous study with X. campestris pv. campestris (causal agent of black rot of crucifers), six functional domains for xanthomonadin production were identified within a 25-kbp genomic clone (pIG102) (25). Sequences from this region (pig) restored pigment production to all 19 induced and naturally occurring xanthomonadin mutants tested (25). Clone pIG102 also conferred xanthomonadin production on a strain of Pseudomonas. Thus, it was concluded that at least some of these functional domains must be structural genes. The original purpose of this work was to perform a transcriptional analysis of pig by using transcriptional lacZ fusions created with the transposon Tn3HoHo1. In the course of this study, we made two unexpected observat...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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pigB determines a diffusible factor needed for extracellular polysaccharide slime and xanthomonadin production in Xanthomonas campestris pv. campestris

Poplawsky

Chun

1997

J Bacteriol

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“…Morphological and physiological uniformity within Xanthomonas has hampered the establishment of a stable taxonomy reflective both of the phenotypic diversity and of the evolutionary relationships within the genus (32,86). The current taxonomy, proposed by Vauterin et al (96) and later substantiated and refined by Rademaker et al (67), however, is robust.…”

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Two New Complete Genome Sequences Offer Insight into Host and Tissue Specificity of Plant Pathogenic Xanthomonas spp

et al. 2011

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Xanthomonas is a large genus of bacteria that collectively cause disease on more than 300 plant species. The broad host range of the genus contrasts with stringent host and tissue specificity for individual species and pathovars. Whole-genome sequences of Xanthomonas campestris pv. raphani strain 756C and X. oryzae pv. oryzicola strain BLS256, pathogens that infect the mesophyll tissue of the leading models for plant biology, Arabidopsis thaliana and rice, respectively, were determined and provided insight into the genetic determinants of host and tissue specificity. Comparisons were made with genomes of closely related strains that infect the vascular tissue of the same hosts and across a larger collection of complete Xanthomonas genomes. The results suggest a model in which complex sets of adaptations at the level of gene content account for host specificity and subtler adaptations at the level of amino acid or noncoding regulatory nucleotide sequence determine tissue specificity.The genus Xanthomonas is a member of the class Gammaproteobacteria and consists of 20 plant-associated species, many of which cause important diseases of crops and ornamentals. Individual species comprise multiple pathogenic variants (pathovars [pv.]). Collectively, members of the genus cause disease on at least 124 monocot species and 268 dicot species, including fruit and nut trees, solanaceous and brassicaceous plants, and cereals (32). They cause a variety of symptoms, including necrosis, cankers, spots, and blight, and they affect a variety of plant parts, including leaves, stems, and fruits (47). The broad host range of the genus contrasts strikingly with the * Corresponding author. Mailing address:

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“…Many of them can also survive and multiply on plant leaf surfaces as epiphytes without affecting the host (15,44). A characteristic feature of most xanthomonads is the production of yellow, membrane-bound (46), halogenated, aryl-polyene pigments (2, 3) called xanthomonadins, which serve as useful chemotaxonomic (45) and diagnostic markers (41).…”

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Genetic Locus Encoding Functions Involved in Biosynthesis and Outer Membrane Localization of Xanthomonadin in Xanthomonas oryzae pv. oryzae

et al. 2002

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Xanthomonadins are membrane-bound, brominated, aryl-polyene pigments specific to the genus Xanthomonas. We have characterized a genetic locus (pig) from Xanthomonas oryzae pv. oryzae which contains four open reading frames (ORFs) that are essential for xanthomonadin production. Three of these ORFs are homologous to acyl carrier proteins, dehydratases, and acyl transferases, suggesting a type II polyketide synthase pathway for xanthomonadin biosynthesis. The fourth ORF has no homologue in the database. For the first time, we report that a putative cytoplasmic membrane protein encoded in the pig locus is required for outer membrane localization of xanthomonadin in X. oryzae pv. oryzae. We also report the identification of a novel 145-bp palindromic Xanthomonas repetitive intergenic consensus element that is present in two places in the pig locus. We estimate that more than 100 copies of this element might be present in the genome of X. oryzae pv. oryzae and other xanthomonads.Members of the genus Xanthomonas cause diseases in a wide range of host plants (25). Many of them can also survive and multiply on plant leaf surfaces as epiphytes without affecting the host (15,44). A characteristic feature of most xanthomonads is the production of yellow, membrane-bound (46), halogenated, aryl-polyene pigments (2, 3) called xanthomonadins, which serve as useful chemotaxonomic (45) and diagnostic markers (41). Xanthomonadin is not essential for in planta growth of bacterial cells (13,35,48). However, it is being established progressively that xanthomonadin protects bacteria against photooxidative damage. Pigment-deficient mutants of Xanthomonas juglandis (20), Xanthomonas oryzae pv. oryzae (37), and Xanthomonas campestris pv. campestris (33) are more susceptible to photooxidative damage than are wild-type strains. In vitro, xanthomonadin protects membrane lipids in egg-phosphatidylcholine liposomes against peroxidation (37). A transposon-induced xanthomonadin-deficient mutant of X. campestris pv. campestris has been recently shown to be 1,000-fold reduced for epiphytic survival in conditions of high light intensity (33). These observations suggest that xanthomonadin might aid the survival of xanthomonads on plant leaf surfaces by providing protection against photooxidative damage. In spite of their apparent importance, very little is known about the biosynthesis and mechanism of action of xanthomonadins.An 18.6-kb genomic region from X. campestris pv. campestris that contains seven transcriptional units (pig genes) required for xanthomonadin production has been isolated (34, 35). One of the transcriptional units, pigB, is involved in biosynthesis of a diffusible factor that affects the production of xanthomonadin as well as extracellular polysaccharide (34). The unavailability of nucleotide sequences for these transcriptional units, however, limits further insight into the mechanism of xanthomonadin biosynthesis. X. oryzae pv. oryzae mutants that are defective in shikimate dehydrogenase activity have been shown to be deficie...

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The Genus Xanthomonas

Cited by 63 publications

References 110 publications

pigB determines a diffusible factor needed for extracellular polysaccharide slime and xanthomonadin production in Xanthomonas campestris pv. campestris

pigB determines a diffusible factor needed for extracellular polysaccharide slime and xanthomonadin production in Xanthomonas campestris pv. campestris

Two New Complete Genome Sequences Offer Insight into Host and Tissue Specificity of Plant Pathogenic Xanthomonas spp

Genetic Locus Encoding Functions Involved in Biosynthesis and Outer Membrane Localization of Xanthomonadin in Xanthomonas oryzae pv. oryzae

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