Molecular and Evolutionary Analyses of <i>Pseudomonas syringae</i> pv. <i>tomato</i> Race 1

Kunkeaw, Suparat; Tan, Steven; Coaker, Gitta

doi:10.1094/mpmi-23-4-0415

Cited by 55 publications

(66 citation statements)

References 56 publications

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“…This method of crop protection has been actively used by geneticists, breeders, and farmers for over 100 y. However, whereas some R proteins have been effective in the field for decades, others were defeated in a single season (1,2). Our inability to a priori predict which R proteins will confer broad spectrum, durable resistance is a major limitation to crop improvement efforts and stems from an incomplete understanding of the genomic diversity present in a pathogen population.…”

Section: P-eif2αmentioning

confidence: 99%

High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance

Bart

Cohn

Kassen

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

138

130

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Cassava bacterial blight (CBB), incited by Xanthomonas axonopodis pv. manihotis ( Xam ), is the most important bacterial disease of cassava, a staple food source for millions of people in developing countries. Here we present a widely applicable strategy for elucidating the virulence components of a pathogen population. We report Illumina-based draft genomes for 65 Xam strains and deduce the phylogenetic relatedness of Xam across the areas where cassava is grown. Using an extensive database of effector proteins from animal and plant pathogens, we identify the effector repertoire for each sequenced strain and use a comparative sequence analysis to deduce the least polymorphic of the conserved effectors. These highly conserved effectors have been maintained over 11 countries, three continents, and 70 y of evolution and as such represent ideal targets for developing resistance strategies.

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Section: P-eif2αmentioning

confidence: 99%

High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance

Bart

Cohn

Kassen

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

138

130

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“…Thus, the selection pressure may have forced plants to evolve the Pto gene encoding a protein that is recalcitrant to the E3 ligase activity of AvrPtoB and capable of recognizing two different domains in the N terminus of AvrPtoB to activate ETI (Martin, 2012;Mathieu et al, 2014). However, a previous study of the avrPtoB gene from the Pst strain T1 ) and a more recent study of Pst race 1 strains collected from the fields of California indicated that Pst may have evolved a mechanism to reduce the accumulation of AvrPtoB to escape host detection by Pto while preserving a degree of their virulence activity (Kunkeaw et al, 2010), which continues the theme of an arms race in the coevolution of Pst and tomato.…”

Section: Discussionmentioning

confidence: 99%

A Subset of Ubiquitin-Conjugating Enzymes Is Essential for Plant Immunity

et al. 2016

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Of the three classes of enzymes involved in ubiquitination, ubiquitin-conjugating enzymes (E2) have been often incorrectly considered to play merely an auxiliary role in the process, and few E2 enzymes have been investigated in plants. To reveal the role of E2 in plant innate immunity, we identified and cloned 40 tomato genes encoding ubiquitin E2 proteins. Thioester assays indicated that the majority of the genes encode enzymatically active E2. Phylogenetic analysis classified the 40 tomato E2 enzymes into 13 groups, of which members of group III were found to interact and act specifically with AvrPtoB, a Pseudomonas syringae pv tomato effector that uses its ubiquitin ligase (E3) activity to suppress host immunity. Knocking down the expression of group III E2 genes in Nicotiana benthamiana diminished the AvrPtoB-promoted degradation of the Fen kinase and the AvrPtoB suppression of host immunity-associated programmed cell death. Importantly, silencing group III E2 genes also resulted in reduced pattern-triggered immunity (PTI). By contrast, programmed cell death induced by several effector-triggered immunity elicitors was not affected on group III-silenced plants. Functional characterization suggested redundancy among group III members for their role in the suppression of plant immunity by AvrPtoB and in PTI and identified UBIQUITIN-CONJUGATING11 (UBC11), UBC28, UBC29, UBC39, and UBC40 as playing a more significant role in PTI than other group III members. Our work builds a foundation for the further characterization of E2s in plant immunity and reveals that AvrPtoB has evolved a strategy for suppressing host immunity that is difficult for the plant to thwart.Ubiquitination as a major posttranslational modification of proteins in eukaryotes has emerged in recent years as an important regulatory mechanism underlying plant innate immunity Fu et al., 2012;Marino et al., 2012;Li et al., 2014). The ubiquitination process involves a consecutive, threestep enzymatic cascade that is catalyzed by three different classes of enzymes: ubiquitin-activating (E1), ubiquitin-conjugating (E2), and ubiquitin ligase (E3) enzymes. The first step of the process activates ubiquitin, a highly conserved 76-amino acid protein, in an ATP-dependent manner by attaching ubiquitin to an E1 enzyme. The activated ubiquitin is then transferred from the E1 to the Cys residue at the active site of an E2 conjugating enzyme. An E3 ligase then recruits the substrate protein to the E2 to transfer the ubiquitin molecule from E2 to the substrate. Through the action of E1, E2, and E3, ubiquitin is covalently attached usually to the Lys residue of a substrate through an isopeptide bond (Hershko and Ciechanover, 1998). Of the three enzymes involved in ubiquitination, E3 ubiquitin ligases have been the focus of many studies due to their key role in determining substrate specificity for the ubiquitination

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“…Samples for quantitative PCR were collected 6 h post inoculation. To analyze effector expression from Pto DC3000, bacteria were grown overnight in hrp-inducing minimal medium, and proteins were harvested as described previously (Kunkeaw et al, 2010).…”

Section: Bacterial Inoculations and Growth Curve Analysesmentioning

confidence: 99%

The Pseudomonas syringae Effector HopQ1 Promotes Bacterial Virulence and Interacts with Tomato 14-3-3 Proteins in a Phosphorylation-Dependent Manner

Yadeta

Elmore

et al. 2013

Plant Physiology

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A key virulence strategy of bacterial pathogens is the delivery of multiple pathogen effector proteins into host cells during infection. The Hrp outer protein Q (HopQ1) effector from Pseudomonas syringae pv tomato (Pto) strain DC3000 is conserved across multiple bacterial plant pathogens. Here, we investigated the virulence function and host targets of HopQ1 in tomato (Solanum lycopersicum). Transgenic tomato lines expressing dexamethasone-inducible HopQ1 exhibited enhanced disease susceptibility to virulent Pto DC3000, the Pto ƊhrcC mutant, and decreased expression of a pathogen-associated molecular pattern-triggered marker gene after bacterial inoculation. HopQ1-interacting proteins were coimmunoprecipitated and identified by mass spectrometry. HopQ1 can associate with multiple tomato 14-3-3 proteins, including TFT1 and TFT5. HopQ1 is phosphorylated in tomato, and four phosphorylated peptides were identified by mass spectrometry. HopQ1 possesses a conserved mode I 14-3-3 binding motif whose serine-51 residue is phosphorylated in tomato and regulates its association with TFT1 and TFT5. Confocal microscopy and fractionation reveal that HopQ1 exhibits nucleocytoplasmic localization, while HopQ1 dephosphorylation mimics exhibit more pronounced nuclear localization. HopQ1 delivered from Pto DC3000 was found to promote bacterial virulence in the tomato genotype Rio Grande 76R. However, the HopQ1(S51A) mutant delivered from Pto DC3000 was unable to promote pathogen virulence. Taken together, our data demonstrate that HopQ1 enhances bacterial virulence and associates with tomato 14-3-3 proteins in a phosphorylation-dependent manner that influences HopQ1’s subcellular localization and virulence-promoting activities in planta.

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Molecular and Evolutionary Analyses of Pseudomonas syringae pv. tomato Race 1

Cited by 55 publications

References 56 publications

High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance

High-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance

A Subset of Ubiquitin-Conjugating Enzymes Is Essential for Plant Immunity

The Pseudomonas syringae Effector HopQ1 Promotes Bacterial Virulence and Interacts with Tomato 14-3-3 Proteins in a Phosphorylation-Dependent Manner

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