PthA4AT, a 7.5‐repeats transcription activator‐like (TAL) effector from Xanthomonas citri ssp. citri, triggers citrus canker resistance

Roeschlin, Roxana Andrea; Uviedo, Facundo; García, Lucila; Molina, María C. Ríos de; Favaro, María Alejandra; Chiesa, María Amalia; Tasselli, Sabrina Emilse; Franco-Zorrilla, José Manuel; Forment, Javier; Gadea, José; Maraño, María Rosa

doi:10.1111/mpp.12844

Cited by 15 publications

(16 citation statements)

References 75 publications

(107 reference statements)

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“…TALEs are pathogenicity determinants in numerous Xanthomonas species that activate host-specific susceptibility (S) genes to promote disease [7]. Conversely, TALEs induce immune responses leading to incompatible interactions [80][81][82][83]. TALE-mediated activation of immune responses in resistant plants can occur by direct induction of the executor resistance (R) gene [18] or by recognition of TALEs by NB-LRR-resistance proteins [15,16].…”

Section: Plos Pathogensmentioning

confidence: 99%

The immunity of Meiwa kumquat against Xanthomonas citri is associated with a known susceptibility gene induced by a transcription activator-like effector

Teper

et al. 2020

PLoS Pathog

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Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most devastating diseases in citrus. Meiwa kumquat (Fortunella crassifolia) has shown a durable resistance against Xcc. Here, we aimed to characterize the mechanisms responsible for such a durable resistance by characterizing the transcriptional and physiological responses of Meiwa kumquat to Xcc. Inoculation of Meiwa kumquat with Xcc promoted immune responses such as upregulation of PR genes, accumulation of salicylic acid, hypersensitive response (HR)-like cell death and early leaf abscission. Hypertrophy and hyperplasia symptoms, which are known to be caused by Xcc-induction of the canker susceptibility gene LOB1 through the transcription activator-like effector (TALE) PthA4, always appear prior to the development of cell death. Mutation of pthA4 in Xcc abolished the induction of LOB1, canker symptoms, cell death, and leaf abscission and reduced the expression of PR genes in inoculated kumquat leaves without reducing Xcc titers in planta. Transcriptome analysis demonstrated that PthA4 promotes plant biotic and abiotic stress responses and the biosynthesis of abscisic acid. Transcriptional induction of LOB1 homologs in Meiwa kumquat by Xcc pthA4 mutant strains carrying a repertoire of designer TALEs promoted the elicitation of HR-like phenotype and leaf abscission, suggesting that kumquat response to Xcc is associated with upregulation of LOB1. Our study suggests a novel mechanism of plant resistance to Xanthomonas via elicitation of immune responses by upregulation of a host susceptibility gene.

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Section: Plos Pathogensmentioning

confidence: 99%

The immunity of Meiwa kumquat against Xanthomonas citri is associated with a known susceptibility gene induced by a transcription activator-like effector

Teper

et al. 2020

PLoS Pathog

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“…This family of genes codes for proteins that trigger the activation of specific plant genes and aid plant infection. While one of these genes (pthA4) is recognized as the major pathogenicity determinant of Xcc pathotype A, Xcc genomes always contain several alternative TALE genes, some of which were found to modify its virulence (47,48). Until recently, TALE genes were thought to be only plasmid encoded in Xcc.…”

Section: Genetic Support Of Tale Genesmentioning

confidence: 99%

“…Indeed, some key phenotypes are encoded by plasmid genes: streptomycin resistance (26), copper resistance (24,27) and most importantly type III transcriptionactivator like effector (TALE) genes (28). Xcc TALEs include a large repertoire of related but highly variable genes, of which pthA4 is required for pathogenicity (29).…”

Section: Introductionmentioning

confidence: 99%

Time-calibrated genomic evolution of a monomorphic bacterium during its establishment as an endemic crop pathogen

Richard¹,

Pruvost²,

Balloux

et al. 2020

Preprint

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AbstractThe reconstruction of the evolutionary histories of pathogen populations in space and time has greatly improved our understanding of their epidemiology. However, analyses are usually restricted to the non-recombining genomic regions and, thus, fail to inform on the dynamics of the accessory genome. Yet, horizontal gene transfer is of striking importance to the evolution of bacteria as it can redistribute phenotypically important genes. For bacterial pathogens, those include resistance to antimicrobial compounds and virulence factors. Understanding the gene turnover in genomes at microevolutionary scales is key to apprehend the pace of this evolutionary process. Here we addressed this question for the epidemic lineage of a major bacterial plant pathogen, relying on a dense geographic sampling spanning 39 years of evolution. Gene turnover rate exceeded SNP mutation rates by three orders of magnitude. Accessory genes were preferentially plasmid-encoded, but we evidenced a highly plastic chromosomal region hosting ecologically important genes such as transcription activator-like effectors. We argue that turnover of accessory genes provides a potent evolutionary force in monomorphic bacteria, and exemplify this statement retracing the history of a mobile element conferring resistance to copper compounds widely used for the management of plant bacterial pathogens.

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“…This indicates that the absence of canker-like symptoms in lemon leaves infected by an A T strain is not solely an effect of the absence of a functional pthA4 gene. That was confirmed by the inability of A T strains to cause canker in lemon leaves even after the introduction of the pthA4 virulence gene (Roeschlin et al 2019).…”

Section: Type A-etrogmentioning

confidence: 81%

Diversity and copper resistance of Xanthomonas affecting citrus

Behlau

Gochez

Jones

2020

Trop. plant pathol.

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Since citrus canker was first described in the early 1900's, four major types and three species of pathogenic xanthomonads associated to citrus were identified based on the characteristic symptoms and host range. Type A, caused by X. citri subsp. citri, develops typical raised cankered lesions and is pathogenic on most commercial citrus species and cultivars. Types B and C are caused by X. citri pv. aurantifolii which elicits canker lesions. Besides the typical type A, the more aggressive and most widely spread type, other subtypes have been described, such as type A*, type A w , type A-Manatee, type A-Miami, type A-minus pthA, and type-A etrog. The type B strains are found only in Argentina and are more pathogenic on lemon and less aggressive on sweet orange, tangerines and grapefruit. The type C strains are found only in Brazil and are pathogenic only on Key lime. X. alfalfae subsp. citrumelonis, formerly known as type E, causes citrus bacterial spot and is more aggressive on trifoliate citrus and its hybrids. Lesions caused by citrus bacterial spot are flat or sunken and not raised. Several subtypes of X. citri subsp. citri have also been identified. Besides the differences in pathogenicity, xanthomonads may also vary in their sensitivity to copper. Copper resistance has been reported for strains of X. citri subsp. citri and X. alfalfae subsp. citrumelonis and is conferred by the gene clusters copLAB or copABCD. Resistance to copper has serious implications for the use of copper-based bactericides, which are the most important chemicals for the control of diseases caused by Xanthomonas on citrus. Keywords Citrus bacterial spot. Citrus canker. Xanthomonas alfalfae subsp. citrumelonis. X. citri pv. aurantifolii. X. citri subsp. citri. copABCD. copLAB

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PthA4^AT, a 7.5‐repeats transcription activator‐like (TAL) effector from Xanthomonas citri ssp. citri, triggers citrus canker resistance

Cited by 15 publications

References 75 publications

The immunity of Meiwa kumquat against Xanthomonas citri is associated with a known susceptibility gene induced by a transcription activator-like effector

The immunity of Meiwa kumquat against Xanthomonas citri is associated with a known susceptibility gene induced by a transcription activator-like effector

Time-calibrated genomic evolution of a monomorphic bacterium during its establishment as an endemic crop pathogen

Diversity and copper resistance of Xanthomonas affecting citrus

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