Oh, the places they'll go! A survey of phytopathogen effectors and their host targets

Abstract

SUMMARYPhytopathogens translocate effector proteins into plant cells where they sabotage the host cellular machinery to promote infection. An individual pathogen can translocate numerous distinct effectors during the infection process to target an array of host macromolecules (proteins, metabolites, DNA, etc.) and manipulate them using a variety of enzymatic activities. In this review, we have surveyed the literature for effector targets and curated them to convey the range of functions carried out by phytopathogenic proteins inside host cells. In particular, we have curated the locations of effector targets, as well as their biological and molecular functions and compared these properties across diverse phytopathogens. This analysis validates previous observations about effector functions (e.g. immunosuppression), and also highlights some interesting features regarding effector specificity as well as functional diversification of phytopathogen virulence strategies.

A host–pathogen interactome uncovers phytopathogenic strategies to manipulate plant ABA responses

“…It is interesting to note the limited overlap between the interactors HopF3 Pph6 and HopF2 Pto in ATIN, which may reflect significant host target diversification within this effector family. Furthermore, the targets of HopF2 Pto are unrelated to those previously identified for this family, further extending the promiscuity of this effector family (Hurley et al ., ; Khan et al ., ). This promiscuity may be required to contend with the evolved robustness of host signaling networks (Hillmer et al ., ).…”

“…RIN4, BAK1, FLS2, etc. ), unrelated to the interactors that we identified in ATIN, extending the promiscuity of the HopAB family and implicating direct modulation of hormone signaling as a target of this T3SE family beyond PTI/ETI (Khan et al ., ).…”

“…HopI and HopN) or mitochondria (HopG) all interacted with transcription factors in ATIN. Although some of these interactions may represent artefacts of the Y2H approach, many T3SEs have been documented to interact with proteins targeted to multiple compartments within the cell (Khan et al, 2018). This would suggest that effectors can moonlight in multiple locations beyond their prominent cellular address, potentially by piggybacking on host proteins, or via modifications/processing that influence their targeting sequences; an aspect of effector biology that remains to be thoroughly investigated.…”

Plant biotic interactions: from conflict to collaboration

“…Khan et al . () discuss how effectors can interfere with diverse immune mechanisms to promote pathogen fitness, and include an inventory of effector targets of different pathogens with an emphasis on bacterial pathogens, highlighting use of different immunosuppression strategies by different pathogens. Su et al .…”

“…Two articles in this special issue focus on plant effector targets, their locations, their biological and molecular functions, and the resulting complex interplay between plants and pathogens. Khan et al (2018) discuss how effectors can interfere with diverse immune mechanisms to promote pathogen fitness, and include an inventory of effector targets of different pathogens with an emphasis on bacterial pathogens, highlighting use of different immunosuppression strategies by different pathogens. Su et al (2018) describe how effectors interact with and manipulate diverse host targets and how these plant components are guarded by resistance (R) proteins.…”