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BMC Genomics. 2016 Mar 14;17:229. doi: 10.1186/s12864-016-2534-4.

A novel method of transcriptome interpretation reveals a quantitative suppressive effect on tomato immune signaling by two domains in a single pathogen effector protein.

Author information

1
Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853-1801, USA. jnw29@cornell.edu.
2
Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853-1801, USA.
3
Institute of Biotechnology, Cornell University, Ithaca, NY, 14853-1801, USA.
4
Boyce Thompson Institute for Plant Research, Ithaca, NY, 14853-1801, USA. gbm7@cornell.edu.
5
Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853-1801, USA. gbm7@cornell.edu.

Abstract

BACKGROUND:

Effector proteins are translocated into host cells by plant-pathogens to undermine pattern-triggered immunity (PTI), the plant response to microbe-associated molecular patterns that interferes with the infection process. Individual effectors are found in variable repertoires where some constituents target the same pathways. The effector protein AvrPto from Pseudomonas syringae has a core domain (CD) and C-terminal domain (CTD) that each promotes bacterial growth and virulence in tomato. The individual contributions of each domain and whether they act redundantly is unknown.

RESULTS:

We use RNA-Seq to elucidate the contribution of the CD and CTD to the suppression of PTI in tomato leaves 6 h after inoculation. Unexpectedly, each domain alters transcript levels of essentially the same genes but to a different degree. This difference, when quantified, reveals that although targeting the same host genes, the two domains act synergistically. AvrPto has a relatively greater effect on genes whose expression is suppressed during PTI, and the effect on these genes appears to be diminished by saturation.

CONCLUSIONS:

RNA-Seq profiles can be used to observe relative contributions of effector subdomains to PTI suppression. Our analysis shows the CD and CTD multiplicatively affect the same gene transcript levels with a greater relative impact on genes whose expression is suppressed during PTI. The higher degree of up-regulation versus down-regulation during PTI is plausibly an evolutionary adaptation against effectors that target immune signaling.

KEYWORDS:

Pattern-triggered immunity; Plant immunity; Pseudomonas syringae; RNA-Seq; Type III effectors

PMID:
26976140
PMCID:
PMC4790048
DOI:
10.1186/s12864-016-2534-4
[Indexed for MEDLINE]
Free PMC Article

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