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Genome sequencing reveals a new lineage associated with lablab bean and genetic exchange between Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans.

Aritua V, Harrison J, Sapp M, Buruchara R, Smith J, Studholme DJ - Front Microbiol (2015)

Bottom Line: This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread.The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines.Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.

View Article: PubMed Central - PubMed

Affiliation: International Center for Tropical Agriculture Kampala, Uganda.

ABSTRACT
Common bacterial blight is a devastating seed-borne disease of common beans that also occurs on other legume species including lablab and Lima beans. We sequenced and analyzed the genomes of 26 strains of Xanthomonas axonopodis pv. phaseoli and X. fuscans subsp. fuscans, the causative agents of this disease, collected over four decades and six continents. This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread. The bacterial strain from Lima bean fell within the previously described Genetic Lineage 1, along with the pathovar type strain (NCPPB 3035). The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines. Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.

No MeSH data available.


Related in: MedlinePlus

Disruption of the hmgA gene in GL fuscans. The cartoon illustrates a sequence polymorphism in the hmgA gene whereby all of the sequenced GL fuscans strains (including previously sequenced 4834-R and CFBP4884) have a single-nucleotide deletion that results in a frame-shift and premature stop codon. All of the Xap GL 1 and lablab-associated strains encode a full-length protein product.
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Figure 10: Disruption of the hmgA gene in GL fuscans. The cartoon illustrates a sequence polymorphism in the hmgA gene whereby all of the sequenced GL fuscans strains (including previously sequenced 4834-R and CFBP4884) have a single-nucleotide deletion that results in a frame-shift and premature stop codon. All of the Xap GL 1 and lablab-associated strains encode a full-length protein product.

Mentions: Some bacterial strains from CBB infections produce a brown pigment when grown in tyrosine-containing medium and are therefore described as “fuscous.” The pigment is not believed to be directly associated with virulence (Gilbertson et al., 1991; Fourie, 2002) but fuscous strains tend to be very virulent on bean (Birch et al., 1997; Toth et al., 1998). The brown color arises from oxidized homogentisic acid (2,5 dihydroxyphenyl acetic acid), an intermediate in the tyrosine catabolic pathway that gets secreted and oxidized in these fuscous strains (Goodwin and Sopher, 1994). Genome sequencing of the fuscous strain Xff 4834-R revealed a single-nucleotide deletion in hmgA, the gene encoding homogentisate oxygenase (Darrasse et al., 2013b). This enzyme catalyzes a step in the tyrosine degradation pathway that converts tyrosine to fumarate and hence its inactivation likely disrupts tyrosine degradation leading to accumulation of homogentisate and its subsequent oxidation to form the brown pigment. Consistent with this hypothesis, we found that the single-nucleotide deletion was present in all of the sequenced strains belonging to GL fuscans resulting in a predicted protein product that is truncated, while the hmgA gene was intact in all of the Xap GL1 and lablab-associated Xap genomes (see Figure 10).


Genome sequencing reveals a new lineage associated with lablab bean and genetic exchange between Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans.

Aritua V, Harrison J, Sapp M, Buruchara R, Smith J, Studholme DJ - Front Microbiol (2015)

Disruption of the hmgA gene in GL fuscans. The cartoon illustrates a sequence polymorphism in the hmgA gene whereby all of the sequenced GL fuscans strains (including previously sequenced 4834-R and CFBP4884) have a single-nucleotide deletion that results in a frame-shift and premature stop codon. All of the Xap GL 1 and lablab-associated strains encode a full-length protein product.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595841&req=5

Figure 10: Disruption of the hmgA gene in GL fuscans. The cartoon illustrates a sequence polymorphism in the hmgA gene whereby all of the sequenced GL fuscans strains (including previously sequenced 4834-R and CFBP4884) have a single-nucleotide deletion that results in a frame-shift and premature stop codon. All of the Xap GL 1 and lablab-associated strains encode a full-length protein product.
Mentions: Some bacterial strains from CBB infections produce a brown pigment when grown in tyrosine-containing medium and are therefore described as “fuscous.” The pigment is not believed to be directly associated with virulence (Gilbertson et al., 1991; Fourie, 2002) but fuscous strains tend to be very virulent on bean (Birch et al., 1997; Toth et al., 1998). The brown color arises from oxidized homogentisic acid (2,5 dihydroxyphenyl acetic acid), an intermediate in the tyrosine catabolic pathway that gets secreted and oxidized in these fuscous strains (Goodwin and Sopher, 1994). Genome sequencing of the fuscous strain Xff 4834-R revealed a single-nucleotide deletion in hmgA, the gene encoding homogentisate oxygenase (Darrasse et al., 2013b). This enzyme catalyzes a step in the tyrosine degradation pathway that converts tyrosine to fumarate and hence its inactivation likely disrupts tyrosine degradation leading to accumulation of homogentisate and its subsequent oxidation to form the brown pigment. Consistent with this hypothesis, we found that the single-nucleotide deletion was present in all of the sequenced strains belonging to GL fuscans resulting in a predicted protein product that is truncated, while the hmgA gene was intact in all of the Xap GL1 and lablab-associated Xap genomes (see Figure 10).

Bottom Line: This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread.The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines.Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.

View Article: PubMed Central - PubMed

Affiliation: International Center for Tropical Agriculture Kampala, Uganda.

ABSTRACT
Common bacterial blight is a devastating seed-borne disease of common beans that also occurs on other legume species including lablab and Lima beans. We sequenced and analyzed the genomes of 26 strains of Xanthomonas axonopodis pv. phaseoli and X. fuscans subsp. fuscans, the causative agents of this disease, collected over four decades and six continents. This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread. The bacterial strain from Lima bean fell within the previously described Genetic Lineage 1, along with the pathovar type strain (NCPPB 3035). The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines. Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.

No MeSH data available.


Related in: MedlinePlus