Evolution of Transcription Activator-Like Effectors in Xanthomonas oryzae

Erkes, Annett; Reschke, Maik; Boch, Jens; Grau, Jan

doi:10.1093/gbe/evx108

Cited by 50 publications

(51 citation statements)

References 39 publications

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“…S14A and B). This observation aligned with other reports which link the evolution of Xoo effector genes to active recombination events [68]. Probably the strong host selection imposed by Xa4 drove the expansion of PX-A1 in nature and the absence of other forces (e.g.…”

Section: Px-a1 Emerge Recently and Became Dominant In The Philippinessupporting

confidence: 91%

The Green Revolution shaped the population structure of the rice pathogen Xanthomonas oryzae pv. oryzae

et al. 2019

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The impact of modern agriculture on the evolutionary trajectory of plant pathogens is a central question for crop sustainability. The Green Revolution replaced traditional rice landraces with high-yielding varieties, creating a uniform selection pressure that allows measuring the effect of such intervention. In this study, we analyzed a unique historical pathogen record to assess the impact of a major resistance gene, Xa4, in the population structure of Xanthomonas oryzae pv. oryzae (Xoo) collected in the Philippines in a span of 40 years. After the deployment of Xa4 in the early 1960s, the emergence of virulent pathogen groups was associated with the increasing adoption of rice varieties carrying Xa4, which reached 80% of the total planted area. Whole genomes analysis of a representative sample suggested six major pathogen groups with distinctive signatures of selection in genes related to secretion system, cell-wall degradation, lipopolysaccharide production, and detoxification of host defense components. Association genetics also suggested that each population might evolve different mechanisms to adapt to Xa4. Interestingly, we found evidence of strong selective sweep affecting several populations in the mid-1980s, suggesting a major bottleneck that coincides with the peak of Xa4 deployment in the archipelago. Our study highlights how modern agricultural practices facilitate the adaptation of pathogens to overcome the effects of standard crop improvement efforts.

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Section: Px-a1 Emerge Recently and Became Dominant In The Philippinessupporting

confidence: 91%

The Green Revolution shaped the population structure of the rice pathogen Xanthomonas oryzae pv. oryzae

et al. 2019

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“…Distribution of TALEs varies in Xanthomonas species depending on host specificity and geographic origin [46]. X. oryzae pathogens typically harbor large TALE repertoires [47], followed by X. campestris [48]. Interestingly, among X. arboricola, only pathovar corylina presents a TALE homolog [49].…”

Section: Discussionmentioning

confidence: 99%

Genome-Wide Profiling and Phylogenetic Analysis of the SWEET Sugar Transporter Gene Family in Walnut and Their Lack of Responsiveness to Xanthomonas arboricola pv. juglandis Infection

Jiang

Balan

Assis

et al. 2020

IJMS

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Following photosynthesis, sucrose is translocated to sink organs, where it provides the primary source of carbon and energy to sustain plant growth and development. Sugar transporters from the SWEET (sugar will eventually be exported transporter) family are rate-limiting factors that mediate sucrose transport across concentration gradients, sustain yields, and participate in reproductive development, plant senescence, stress responses, as well as support plant-pathogen interaction, the focus of this study. We identified 25 SWEET genes in the walnut genome and distinguished each by its individual gene structure and pattern of expression in different walnut tissues. Their chromosomal locations, cis-acting motifs within their 5 regulatory elements, and phylogenetic relationship patterns provided the first comprehensive analysis of the SWEET gene family of sugar transporters in walnut. This family is divided into four clades, the analysis of which suggests duplication and expansion of the SWEET gene family in Juglans regia. In addition, tissue-specific gene expression signatures suggest diverse possible functions for JrSWEET genes. Although these are commonly used by pathogens to harness sugar products from their plant hosts, little was known about their role during Xanthomonas arboricola pv. juglandis (Xaj) infection. We monitored the expression profiles of the JrSWEET genes in different tissues of "Chandler" walnuts when challenged with pathogen Xaj417 and concluded that SWEET-mediated sugar translocation from the host is not a trigger for walnut blight disease development. This may be directly related to the absence of type III secretion system-dependent transcription activator-like effectors (TALEs) in Xaj417, which suggests different strategies are employed by this pathogen to promote susceptibility to this major aboveground disease of walnuts.

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“…For the TALE RVDs analysis, we used AnnoTALE version 1.4.1. The TALEs are grouped into classes based on the RVDs that shows possible functional and evolutionary relationship [50,85].…”

Section: Tales Phylogenetic Tree Construction and Rvds Comparisonmentioning

confidence: 99%

Identification of a virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2–18

et al. 2020

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Background: Bacterial blight of cotton (BBC), which is caused by the bacterium Xanthomonas citri pv. malvacearum (Xcm), is a destructive disease in cotton. Transcription activator-like effectors (TALEs), encoded by tal-genes, play critical roles in the pathogenesis of xanthomonads. Characterized strains of cotton pathogenic Xcm harbor 8-12 different tal genes and only one of them is functionally decoded. Further identification of novel tal genes in Xcm strains with virulence contributions are prerequisite to decipher the Xcm-cotton interactions. Results: In this study, we identified six tal genes in Xss-V 2 -18, a highly-virulent strain of Xcm from China, and assessed their role in BBC. RFLP-based Southern hybridization assays indicated that Xss-V 2 -18 harbors the six tal genes on a plasmid. The plasmid-encoded tal genes were isolated by cloning BamHI fragments and screening clones by colony hybridization. The tal genes were sequenced by inserting a Tn5 transposon in the DNA encoding the central repeat region (CRR) of each tal gene. Xcm TALome evolutionary relationship based on TALEs CRR revealed relatedness of Xss-V 2 -18 to MSCT1 and MS14003 from the United States. However, Tal2 of Xss-V 2 -18 differs at two repeat variable diresidues (RVDs) from Tal6 and Tal26 in MSCT1 and MS14003, respectively, inferred functional dissimilarity. The suicide vector pKMS1 was then used to construct tal deletion mutants in Xcm Xss-V 2 -18. The mutants were evaluated for pathogenicity in cotton based on symptomology and growth in planta. Four mutants showed attenuated virulence and all contained mutations in tal2. One tal2 mutant designated M2 was further investigated in complementation assays. When tal2 was introduced into Xcm M2 and expressed in trans, the mutant was complemented for both symptoms and growth in planta, thus indicating that tal2 functions as a virulence factor in Xcm Xss-V 2 -18. Conclusions:Overall, the results demonstrated that Tal2 is a major pathogenicity factor in Xcm strain Xss-V 2 -18 that contributes significantly in BBC. This study provides a foundation for future efforts aimed at identifying susceptibility genes in cotton that are targeted by Tal2.

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Evolution of Transcription Activator-Like Effectors in Xanthomonas oryzae

Cited by 50 publications

References 39 publications

The Green Revolution shaped the population structure of the rice pathogen Xanthomonas oryzae pv. oryzae

The Green Revolution shaped the population structure of the rice pathogen Xanthomonas oryzae pv. oryzae

Genome-Wide Profiling and Phylogenetic Analysis of the SWEET Sugar Transporter Gene Family in Walnut and Their Lack of Responsiveness to Xanthomonas arboricola pv. juglandis Infection

Identification of a virulence tal gene in the cotton pathogen, Xanthomonas citri pv. malvacearum strain Xss-V2–18

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