Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence
Most plant pathogens are specialists where only few plant species are susceptible, while all other plants are resistant. Unraveling the mechanisms behind this can thus provide valuable information for breeding or engineering crops with durable disease resistance. A group of Pseudomonas syringae stra...
Main Author: | |
---|---|
Other Authors: | |
Format: | Others |
Language: | en_US |
Published: |
Virginia Tech
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/10919/77293 http://scholar.lib.vt.edu/theses/available/etd-12202010-021153/ |
id |
ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-77293 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-VTETD-oai-vtechworks.lib.vt.edu-10919-772932020-09-29T05:38:48Z Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence Yan, Shuangchun Plant Pathology, Physiology, and Weed Science Vinatzer, Boris A. Setubal, João C. Jelesko, John G. Zhang, Liqing Tyler, Brett M. host-microbe interaction callose HopM1 microbial genomics population genetics molecular evolution Arabidopsis thaliana Pseudomonas syringae Most plant pathogens are specialists where only few plant species are susceptible, while all other plants are resistant. Unraveling the mechanisms behind this can thus provide valuable information for breeding or engineering crops with durable disease resistance. A group of Pseudomonas syringae strains with different host ranges while still closely related were thus chosen for comparative study. We confirmed their close phylogenetic relationship. We found evidence supporting that these strains recombined during evolution. The Arabidopsis thaliana and tomato pathogen P. syringae pv. tomato (Pto) DC3000 was found to be an atypical tomato strain, distinct from the typical Pto strains commonly isolated in the field that do not cause disease in A. thaliana, such as Pto T1. Comparing A. thaliana defense responses to DC3000 and T1, we found that T1 is eliciting stronger responses than DC3000. T1 is likely lacking Type III effector genes necessary to suppress plant defense. To test this, we sequenced the genomes of strains that cause and do not cause disease in A. thaliana. Comparative genomics revealed candidate effector genes responsible for this host range difference. Effector genes conserved in strains pathogenic in A. thaliana were expressed in T1 to test whether they would allow T1 to growth better in A. thaliana. Surprisingly, most of them reduced T1 growth. One of the effectors, HopM1, was of particular interest because it is disrupted in typical Pto strains. Although HopM1 has known virulence function in A. thaliana, HopM1 reduced T1 growth in both A. thaliana and tomato. HopM1 also increased the number of bacterial specks but reduced their average size in tomato. Our data suggest that HopM1 can trigger defenses in these plants. Additionally, transgenic detritivore Pseudomonas fluorescens that can secrete HopM1 shows dramatically increased growth in planta. The importance of genetic background of the pathogen for the functions of individual effectors is discussed. T1 cannot be manipulated to become an A. thaliana pathogen by deleting or adding individual genes. We now have a list of genes that can be studied in the future for the molecular basis of host range determination. Ph. D. 2017-04-06T15:44:34Z 2017-04-06T15:44:34Z 2010-12-06 2010-12-20 2016-10-18 2011-01-12 Dissertation Text etd-12202010-021153 http://hdl.handle.net/10919/77293 http://scholar.lib.vt.edu/theses/available/etd-12202010-021153/ en_US In Copyright http://rightsstatements.org/vocab/InC/1.0/ application/pdf application/pdf Virginia Tech |
collection |
NDLTD |
language |
en_US |
format |
Others
|
sources |
NDLTD |
topic |
host-microbe interaction callose HopM1 microbial genomics population genetics molecular evolution Arabidopsis thaliana Pseudomonas syringae |
spellingShingle |
host-microbe interaction callose HopM1 microbial genomics population genetics molecular evolution Arabidopsis thaliana Pseudomonas syringae Yan, Shuangchun Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
description |
Most plant pathogens are specialists where only few plant species are susceptible, while all other plants are resistant. Unraveling the mechanisms behind this can thus provide valuable information for breeding or engineering crops with durable disease resistance. A group of Pseudomonas syringae strains with different host ranges while still closely related were thus chosen for comparative study. We confirmed their close phylogenetic relationship. We found evidence supporting that these strains recombined during evolution. The Arabidopsis thaliana and tomato pathogen P. syringae pv. tomato (Pto) DC3000 was found to be an atypical tomato strain, distinct from the typical Pto strains commonly isolated in the field that do not cause disease in A. thaliana, such as Pto T1. Comparing A. thaliana defense responses to DC3000 and T1, we found that T1 is eliciting stronger responses than DC3000. T1 is likely lacking Type III effector genes necessary to suppress plant defense. To test this, we sequenced the genomes of strains that cause and do not cause disease in A. thaliana. Comparative genomics revealed candidate effector genes responsible for this host range difference. Effector genes conserved in strains pathogenic in A. thaliana were expressed in T1 to test whether they would allow T1 to growth better in A. thaliana. Surprisingly, most of them reduced T1 growth. One of the effectors, HopM1, was of particular interest because it is disrupted in typical Pto strains. Although HopM1 has known virulence function in A. thaliana, HopM1 reduced T1 growth in both A. thaliana and tomato. HopM1 also increased the number of bacterial specks but reduced their average size in tomato. Our data suggest that HopM1 can trigger defenses in these plants. Additionally, transgenic detritivore Pseudomonas fluorescens that can secrete HopM1 shows dramatically increased growth in planta. The importance of genetic background of the pathogen for the functions of individual effectors is discussed. T1 cannot be manipulated to become an A. thaliana pathogen by deleting or adding individual genes. We now have a list of genes that can be studied in the future for the molecular basis of host range determination. === Ph. D. |
author2 |
Plant Pathology, Physiology, and Weed Science |
author_facet |
Plant Pathology, Physiology, and Weed Science Yan, Shuangchun |
author |
Yan, Shuangchun |
author_sort |
Yan, Shuangchun |
title |
Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
title_short |
Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
title_full |
Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
title_fullStr |
Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
title_full_unstemmed |
Using the Bacterial Plant Pathogen Pseudomonas syringae pv. tomato as a Model to Study the Evolution and Mechanisms of Host Range and Virulence |
title_sort |
using the bacterial plant pathogen pseudomonas syringae pv. tomato as a model to study the evolution and mechanisms of host range and virulence |
publisher |
Virginia Tech |
publishDate |
2017 |
url |
http://hdl.handle.net/10919/77293 http://scholar.lib.vt.edu/theses/available/etd-12202010-021153/ |
work_keys_str_mv |
AT yanshuangchun usingthebacterialplantpathogenpseudomonassyringaepvtomatoasamodeltostudytheevolutionandmechanismsofhostrangeandvirulence |
_version_ |
1719344664260116480 |