Genome Sequence Resource for Strains of <i>Pseudomonas syringae</i> Phylogroup 2b and <i>P. viridiflava</i> Phylogroup 7a Causing Bacterial Stem Blight of Alfalfa

Lipps, Savana M.; Samac, Deborah A.; Ishii, Satoshi

doi:10.1094/phyto-12-21-0511-a

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…In the past, PG7 was known under the name of P. viridiflava (Bartoli et al, 2014; Parkinson et al, 2011), a phytopathogen with pectolytic activity and described to cause disease on a wide-range of crops (Conn, 1993; González et al, 2003; Goumans and Chatzaki, 1998; Morris, 1992). Re-classification of P. viridiflava demonstrated that this phytopathogen is defined by two P. syringae PGs (7 and 8), PG7 clade a being the most abundant in both agricultural and non-agricultural habitats (Lipps et al, 2022; Lipps and Samac, 2022). Several herbaceous plants, including A. thaliana , have been described as natural hosts of PG7.…”

Section: Resultsmentioning

confidence: 99%

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

Bartoli

Rigal

Mayjonade

et al. 2022

Preprint

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Phytopathogens are a continuous threat for global food production and security. Emergence or re-emergence of plant pathogens is highly dependent on the environmental conditions affecting pathogen spread and survival. Under climate change, a geographic expansion of pathogen distribution poleward has been observed, potentially resulting in disease outbreaks on crops and wild plants. Therefore, estimating the adaptive potential of plants to novel epidemics and describing its underlying genetic architecture, is a primary need to propose agricultural management strategies reducing pathogen outbreaks, as well as to breed novel plant cultivars adapted to pathogens that might spread in novel habitats as a consequence of climate change. To address this challenge, we inoculated Pseudomonas syringae strains isolated from Arabidopsis thaliana populations located in south-west of France on the highly genetically polymorphic TOU-A A. thaliana population located east-central France. While no adaptive potential was identified in response to most P. syringae strains, the TOU-A population displays a variable disease response to the P. syringae strain JACO-CL belonging to the phylogroup 7 (PG7). This strain carried a reduced T3SS characteristic of the PG7 as well as flexible genomic traits and potential novel effectors. GWA mapping on 192 TOU-A accessions inoculated with JACO-CL revealed a polygenic architecture. The main QTL region encompasses two R genes and the AT5G18310 gene encoding for ubiquitin hydrolase, a target of the AvrRpt2 P. syringae effector. Altogether, our results pave the way for a better understanding of the genetic and molecular basis of the adaptive potential in an ecologically relevant A. thaliana - P. syringae pathosystem.

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Section: Resultsmentioning

confidence: 99%

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

Bartoli

Rigal

Mayjonade

et al. 2022

Preprint

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“…Interestingly, the isolates of P. syringae pv. syringae causing BSB in alfalfa have genes to produce coronatine (COR), which is unusual in this pathovar [ 53 ]. Thus, the sensitivity of tolerant alfalfa plants to COR and other phytotoxins produced by P. syringae pv.…”

Section: Discussionmentioning

confidence: 99%

“…syringae causing BSB is common in the central and western United States (Oregon, California, Colorado, Utah, Wyoming, Ohio, and Minnesota), and it has also been isolated in Australia, Europe, and western Iran [ 4 , 5 ]. The factors underlying the re-emergence of BSB are unknown; however, genetic analysis of the pathogens revealed that both bacteria are diverse and widespread, making a recent introduction of a more virulent pathogen unlikely [ 6 ]. The disease cycle is initiated when the surfaces of alfalfa plants become colonized by bacteria present in rain or from infected plant material [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Genetic Mapping of Tolerance to Bacterial Stem Blight Caused by Pseudomonas syringae pv. syringae in Alfalfa (Medicago sativa L.)

Moya,

Medina,

Herrera

et al. 2023

Plants

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The bacterial stem blight of alfalfa (Medicago sativa L.), first reported in the United States in 1904, has emerged recently as a serious disease problem in the western states. The causal agent, Pseudomonas syringae pv. syringae, promotes frost damage and disease that can reduce first harvest yields by 50%. Resistant cultivars and an understanding of host-pathogen interactions are lacking in this pathosystem. With the goal of identifying DNA markers associated with disease resistance, we developed biparental F1 mapping populations using plants from the cultivar ZG9830. Leaflets of plants in the mapping populations were inoculated with a bacterial suspension using a needleless syringe and scored for disease symptoms. Bacterial populations were measured by culture plating and using a quantitative PCR assay. Surprisingly, leaflets with few to no symptoms had bacterial loads similar to leaflets with severe disease symptoms, indicating that plants without symptoms were tolerant to the bacterium. Genotyping-by-sequencing identified 11 significant SNP markers associated with the tolerance phenotype. This is the first study to identify DNA markers associated with tolerance to P. syringae. These results provide insight into host responses and provide markers that can be used in alfalfa breeding programs to develop improved cultivars to manage the bacterial stem blight of alfalfa.

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Diversity of Strains in the Pseudomonas syringae Complex Causing Bacterial Stem Blight of Alfalfa (Medicago sativa) in the United States

Lipps,

Castell-Miller,

Morris

et al. 2024

Phytopathology®

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Alfalfa growers in the Intermountain West of the United States have recently seen an increased incidence in bacterial stem blight (BSB), which can result in significant herbage yield losses from the first harvest. BSB has been attributed to Pseudomonas syringae pv. syringae and P. viridiflava; however, little is known about the genetic diversity and pathogenicity of these bacteria or their interaction with alfalfa plants. Here, we present a comprehensive phylogenetic and phenotypic analysis of P. syringae and P. viridiflava strains causing BSB on alfalfa. A multi-locus sequence analysis found that they grouped exclusively with P. syringae PG2b and P. viridiflava PG7a. Alfalfa symptoms caused by both bacterial groups were indistinguishable, although there was a large range in mean disease scores for individual strains. Overall, PG2b strains incited significantly greater disease scores than those caused by PG7a strains. Inoculated plants showed browning in the xylem and collapse of epidermal and pith parenchyma cells. Inoculation with a mixture of PG2b and PG7a strains did not result in synergistic activity. The populations of PG2b and PG7a strains were genetically diverse within their clades and did not group by location or haplotype. The PG2b strains had genes for production of the phytotoxin coronatine, which is unusual in PG2b strains. The results indicate that both pathogens are well established on alfalfa across a wide geographic range and that a recent introduction or evolution of more aggressive strains as the basis for emergence of the disease is unlikely.

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Genome Sequence Resource for Strains of Pseudomonas syringae Phylogroup 2b and P. viridiflava Phylogroup 7a Causing Bacterial Stem Blight of Alfalfa

Cited by 3 publications

References 7 publications

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

Unraveling the genetic architecture of the adaptive potential of Arabidopsis thaliana to face the bacterial pathogen Pseudomonas syringae in the context of global change

Genetic Mapping of Tolerance to Bacterial Stem Blight Caused by Pseudomonas syringae pv. syringae in Alfalfa (Medicago sativa L.)

Diversity of Strains in the Pseudomonas syringae Complex Causing Bacterial Stem Blight of Alfalfa (Medicago sativa) in the United States

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