Variation in Aggressiveness of<i>Xanthomonas campestris</i>pv.<i>citrumelo</i>Associated with Citrus Bacterial Spot in Florida Citrus Nurseries

Graham, J. H.; Gottwald, T. R.

doi:10.1094/phyto-80-190

Cited by 43 publications

(44 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Further research revealed that the CBS pathogen is variable but widely distributed in the state and does not have the same host range as the Asiatic strain (34). CBS bacteria are most aggressive on trifoliate orange hybrids, including Swingle citrumelo (36). Populations of CBS bacteria decreased or varied in leaves of grapefruit (92).…”

mentioning

confidence: 99%

“…citri, the X. axonopodis pv. citrumelo strains isolated from Florida nurseries were found to vary widely in aggressiveness from each other (36). Restriction fragment length polymorphism analysis by Hartung and Civerolo (45) showed that X. axonopodis pv.…”

mentioning

confidence: 99%

“…To address this question, comparative genomic study was conducted in this present research by completing the genome sequence of X. axonopodis pv. citrumelo strain F1 (36). In comparison with X. axonopodis pv.…”

mentioning

confidence: 99%

“…citri, X. axonopodis pv. citrumelo is a genetically, pathogenically, and serologically diverse pathogen (4,29,36,45). We decided to sequence X. axonopodis pv.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificit

et al. 2011

View full text Add to dashboard Cite

Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.Xanthomonas is an important genus of plant pathogenic bacteria (87). These Gram-negative rod-shaped pathogens belong to the class Gammaproteobacteria and can infect over 350 species of plants (12). Among the diseases on citrus, citrus bacterial canker (CBC) and citrus bacterial spot (CBS) are caused by distinct pathovars of Xanthomonas species. Citrus canker is caused by several pathogenic variants of X. axonopodis pv. citri (synonyms Xanthomonas citri, Xanthomonas campestris pv. citri, or Xanthomonas citri subsp. citri) (90, 109), whereas CBS is caused by X. axonopodis pv. citrumelo. X. axonopodis pv. citri strain 306 with a suspected origin in southeastern Asia causes Asiatic type A canker and is the most widespread and virulent form of CBC. It produces hyperplasic and hypertrophic (corky) lesions surrounded by oily or watersoaked margins and a yellow halo on leaves, stems, and fruits.In 1984, a disease similar to citrus canker was discovered in citrus nurseries in central Florida, leading to the destruction of millions of seedlings (98). This new form of citrus canker was described as the "E-strain" group, also known as nursery strain canker. Leaf spots of this strain are irregular to round, 3 to 5 mm in diameter, flat, water so...

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…citri, X. axonopodis pv. citrumelo is a genetically, pathogenically, and serologically diverse pathogen (4,29,36,45). We decided to sequence X. axonopodis pv.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificit

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Precise discrimination of pathovars and strains of Xanthomonas axonopodis that cause citrus bacterial canker has been particularly important for risk assessment in eradication programmes for this leaf-and fruit-spotting disease in Florida and elsewhere. Misidentification and unclear classification of xanthomonads have occurred in the past, resulting in unnecessary quarantine regulations and economic losses (Schoulties et al, 1987;Gabriel et al, 1989;Graham & Gottwald, 1990;Graham et al, 1992).Among DNA-based methods for bacterial characterization, DNA-DNA reassociation is considered to be a major determinant for definition of bacterial species; a hybridization value of 70 % or greater has been used to group related pathovars into species of Xanthomonas (Wayne et al, 1987;Vauterin et al, 1995;Louws et al, 1999). Nevertheless, several other criteria have also been applied for differentiation at the species, pathovar or strain levels ( Van den Mooter & Swings, 1990;Vauterin et al, 1991Vauterin et al, , 1995.…”

mentioning

confidence: 99%

The leucine-responsive regulatory protein (lrp) gene for characterization of the relationship among Xanthomonas species

Cubero

Graham

2004

International Journal of Systematic and Evolutionary Microbiology

View full text Add to dashboard Cite

Characterization of strains of Xanthomonas axonopodis pv. citri by using DNA fingerprints that were generated from primers for enterobacterial repetitive intergenic consensus (ERIC) elements led to the discovery of differential sequences for a leucine-responsive regulatory protein (lrp) gene in two subgroups of strains with different host ranges on Citrus spp. DNA hybridization and PCR-based assays that used different sets of primers were designed to detect the core sequence, as well as to obtain the entire sequence of the lrp gene for several Xanthomonas species and pathovars. Higher variability was observed at the nucleotide level than at the amino acid level among the different species and pathovars, revealing selection pressure on the lrp gene, which is presumably due to an essential role of the gene in bacterial metabolism. Moderate variability in the 39 and 59 domains was used to study relationships among different species within the genus Xanthomonas. Species of this genus that were isolated from citrus, as well as other pathovars of X. axonopodis, showed highly similar lrp gene sequences, whereas other Xanthomonas species, especially Xanthomonas campestris, had sequences that were more dissimilar to that of X. axonopodis. Thus, the lrp gene sequence is useful to distinguish X. axonopodis pv. citri groups and promising for polyphasic taxonomic analysis of the genus Xanthomonas. Data from analysis of lrp gene sequences support the current concepts for classification of xanthomonads, which are based on other approaches. INTRODUCTIONXanthomonas spp. are ubiquitous bacterial pathogens that affect many economically important plant species (Leyns et al., 1984). Much revision of the classification of xanthomonads into several species and infraspecific pathovars has been proposed in recent years (Dye & Lelliott, 1974;Vauterin et al., 1995Vauterin et al., , 2000Schaad et al., 2000). Despite the broad host range of and the importance of the diseases caused by xanthomonads, taxonomy and classification of this bacterial group remain controversial Schaad et al., 2000;Vauterin et al., 2000;Young et al., 2001). Accurate classification of Xanthomonas species is not only important for basic knowledge of the phylogeny of this genus, but also has practical implications for global regulation of exotic diseases that are caused by these plant pathogens. Precise discrimination of pathovars and strains of Xanthomonas axonopodis that cause citrus bacterial canker has been particularly important for risk assessment in eradication programmes for this leaf-and fruit-spotting disease in Florida and elsewhere. Misidentification and unclear classification of xanthomonads have occurred in the past, resulting in unnecessary quarantine regulations and economic losses (Schoulties et al., 1987;Gabriel et al., 1989;Graham & Gottwald, 1990;Graham et al., 1992).Among DNA-based methods for bacterial characterization, DNA-DNA reassociation is considered to be a major determinant for definition of bacterial species; a hybridization value of 70 % ...

show abstract

Molecular Techniques for Detection of Microbial Pathogens

Narayanasamy

Molecular Biology in Plant Pathogenesis and Disease Management

View full text Add to dashboard Cite

Detection, identification and differentiation of microbial plant pathogens -oomycetes, fungi, bacteria, phytoplasmas, viruses and viroids -infecting various crops constitute the basic step for the development of effective crop disease management systems. The conventional cultural methods involving isolation and studying the morphological characteristics using microscope are labor intensive and cumbersome, yielding sometimes, inconclusive results. The molecular techniques, on the other hand, are able to provide precise, reliable and reproducible results rapidly, facilitating early disease management decisions. Biochemical, immunological and nucleic acid-based assays have been preferred, because of the distinct advantages over the conventional methods. The molecular techniques have been very useful in the identification of obligate pathogens causing diseases such as downy mildews, powdery mildews and rusts and also fungi that grow very slowly in the culture media, taking several weeks to produce spore forms that can be used for identification. The availability of antisera, primers and commercial kits has led to widespread application of the molecular techniques for on-site detection during field surveys for assessing the distribution of existing pathogens, occurrence of new/introduced pathogens or strains and for preventing introduction of new pathogens through seeds or planting materials. Furthermore, molecular techniques have been demonstrated to be useful in breeding programs to identify sources of resistance to disease(s). Several protocols for molecular techniques, useful for researchers and students are presented in the Appendix.

show abstract

Variation in Aggressiveness ofXanthomonas campestrispv.citrumeloAssociated with Citrus Bacterial Spot in Florida Citrus Nurseries

Cited by 43 publications

References 0 publications

Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificit

Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificit

The leucine-responsive regulatory protein (lrp) gene for characterization of the relationship among Xanthomonas species

Molecular Techniques for Detection of Microbial Pathogens

Contact Info

Product

Resources

About