The genetic arms race between plant and Xanthomonas: lessons learned from TALE biology

Jiao, Xiaoguo; Lu, Zhanhua; Liu, Wei; Wang, Shiguang; Lu, Dongbai; Wang, Xiaofei; He, Xiuying

doi:10.1007/s11427-020-1699-4

Cited by 10 publications

(5 citation statements)

References 125 publications

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“…It is clear that additional efforts should be directed to the discovery of executor R genes in horticultural crops via TALE-based techniques. Over the past decade, several useful tools, such as TALE nuclease (TALEN) technology and the split-TALE (sTALE) system, have been established for genome editing, regulation of gene expression, and analysis of protein–protein interaction [ 149 – 151 ]. Development of these technologies will facilitate the improvement of broad-spectrum resistance to fungal pathogens in the breeding of horticultural crops.…”

Section: Novel Strategies To Activate Defense Responses In Horticultu...mentioning

confidence: 99%

Molecular mechanisms underlying multi-level defense responses of horticultural crops to fungal pathogens

Chen

et al. 2022

Horticulture Research

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The horticultural industry helps to enrich and improve the human diet while contributing to growth of the agricultural economy. However, fungal diseases of horticultural crops frequently occur during pre- and post-harvest periods, reducing yields and crop quality and causing huge economic losses and wasted food. Outcomes of fungal diseases depend on both horticultural plant defense responses and fungal pathogenicity. Plant defense responses are highly sophisticated and are generally divided into preformed and induced defense responses. Preformed defense responses include both physical barriers and phytochemicals, which are the first line of protection. Induced defense responses, which include innate immunity (pattern-triggered immunity and effector-triggered immunity), local defense responses, and systemic defense signaling, are triggered to counterstrike fungal pathogens. Therefore, to develop regulatory strategies for horticultural plant resistance, a comprehensive understanding of defense responses and their underlying mechanisms is critical. Recently, integrated multi-omics analyses, CRISPR-Cas9-based gene editing, high-throughput sequencing, and data mining have greatly contributed to identification and functional determination of novel phytochemicals, regulatory factors, and signaling molecules and their signaling pathways in plant resistance. In this review, research progress on defense responses of horticultural crops to fungal pathogens and novel regulatory strategies to regulate induction of plant resistance are summarized, and then, the problems, challenges, and future research directions are examined.

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Section: Novel Strategies To Activate Defense Responses In Horticultu...mentioning

confidence: 99%

Molecular mechanisms underlying multi-level defense responses of horticultural crops to fungal pathogens

Chen

et al. 2022

Horticulture Research

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“…The highly virulent citrus pathogen Xanthomonas axonopodis pv citri carries the pXAC64 plasmid, which is not found in the closely related and weakly virulent pathovar citrumelo . This plasmid carries the transcription activator‐like effector PthA4, which confers the ability to cause canker‐like symptoms on citrus (Boch & Bonas, 2010; Jalan et al ., 2011; Xue et al ., 2021).…”

Section: Discussionmentioning

confidence: 99%

Pseudomonas syringae coffee blight is associated with the horizontal transfer of plasmid‐encoded type III effectors

McTavish,

Almeida,

Tersigni

et al. 2023

New Phytologist

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Summary The emergence of new pathogens is an ongoing threat to human health and agriculture. While zoonotic spillovers received considerable attention, the emergence of crop diseases is less well studied. Here, we identify genomic factors associated with the emergence of Pseudomonas syringae bacterial blight of coffee. Fifty‐three P. syringae strains from diseased Brazilian coffee plants were sequenced. Comparative and evolutionary analyses were used to identify loci associated with coffee blight. Growth and symptomology assays were performed to validate the findings. Coffee isolates clustered in three lineages, including primary phylogroups PG3 and PG4, and secondary phylogroup PG11. Genome‐wide association study of the primary PG strains identified 37 loci, including five effectors, most of which were encoded on a plasmid unique to the PG3 and PG4 coffee strains. Evolutionary analyses support the emergence of coffee blight in PG4 when the coffee‐associated plasmid and associated effectors derived from a divergent plasmid carried by strains associated with other hosts. This plasmid was only recently transferred into PG3. Natural diversity and CRISPR‐Cas9 plasmid curing were used to show that strains with the coffee‐associated plasmid grow to higher densities and cause more severe disease symptoms in coffee. This work identifies possible evolutionary mechanisms underlying the emergence of a new lineage of coffee pathogens.

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“…R genes for race-specific resistance to Xanthomonas TALEs have been cloned from rice ( Xa10 , Xa23 , Xa27 , and Xa7 ) and solanaceous plants ( Bs3 and Bs4C-R ) ( Xue et al., 2020 ; Chen et al., 2021 ; Luo et al., 2021 ). These R genes are not homologous to classical NLR genes and are subdivided into two groups ( Zhang et al., 2015 ).…”

Section: Discussionmentioning

confidence: 99%

“…As a countermeasure, plants have evolved resistance ( R ) genes that “trap” TALEs and confer immunity. Some R genes, including Xa10 , Xa23 , Xa27 , and Xa7 in rice and Bs3 and Bs4C-R in solanaceous plants, trap TALEs and exhibit TALE-dependent transcription to promote an HR ( Bogdanove et al., 2010 ; Xue et al., 2020 ; Chen et al., 2021 ; Luo et al., 2021 ). The resistance spectra of R genes are diverse and depend on the cognate or “trapped” TALEs in the Xanthomonas population.…”

Section: Introductionmentioning

confidence: 99%

A Xanthomonas transcription activator-like effector is trapped in nonhost plants for immunity

Haq

et al. 2022

Plant Communications

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Xanthomonas oryzae pv. oryzae ( Xoo ), the causal agent of bacterial leaf blight in rice, delivers transcription activator-like effector (TALE) proteins into host cells to activate susceptibility or resistance ( R ) genes that promote disease or immunity, respectively. Nonhost plants serve as potential reservoirs of R genes; consequently, nonhost R genes may trap TALEs to trigger an immune response. In this study, we screened 17 Xoo TALEs for their ability to induce a hypersensitive response (HR) in the nonhost plant Nicotiana benthamiana ( Nb ); only AvrXa10 elicited an HR when transiently expressed in Nb . The HR generated by AvrXa10 required both the central repeat region and the activation domain, suggesting a specific interaction between AvrXa10 and a potential R -like gene in nonhost plants. Evans blue staining and ion leakage measurements confirmed that the AvrXa10-triggered HR was a form of cell death, and the transient expression of AvrXa10 in Nb induced immune responses. Genes targeted by AvrXa10 in the Nb genome were identified by transcriptome profiling and prediction of effector binding sites. Using several approaches ( in vivo reporter assays, electrophoretic mobility-shift assays, targeted designer TALEs, and on-spot gene silencing), we confirmed that AvrXa10 targets NbZnFP1 , a C2H2-type zinc finger protein that resides in the nucleus. Functional analysis indicated that overexpression of NbZnFP1 and its rice orthologs triggered cell death in rice protoplasts. An NbZnFP1 ortholog was also identified in tomato and was specifically activated by AvrXa10. These results demonstrate that NbZnFP1 is a nonhost R gene that traps AvrXa10 to promote plant immunity in Nb .

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The genetic arms race between plant and Xanthomonas: lessons learned from TALE biology

Cited by 10 publications

References 125 publications

Molecular mechanisms underlying multi-level defense responses of horticultural crops to fungal pathogens

Molecular mechanisms underlying multi-level defense responses of horticultural crops to fungal pathogens

Pseudomonas syringae coffee blight is associated with the horizontal transfer of plasmid‐encoded type III effectors

A Xanthomonas transcription activator-like effector is trapped in nonhost plants for immunity

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