This weeks Arabidopsis Research Roundup includes three studies that are led from Norwich Research Park and another from the University of Nottingham. In the latter case Rupert Fray leads an investigation into the scarcely researched process of N6-adenosine methylation of RNA. The next two papers involve members of the Sainsbury lab in Norwich and investigate either the RPS4-RRS1 or FERONIA-LLG1 defence signaling pathways. Finally is a study that originates from the John Innes Centre links the defence response with biotic predation and calcium signaling.
Růžička K,, Zhang M, Campilho A,, Bodi Z, Kashif M, Saleh M, Eeckhout D,, El-Showk S, Li H,, Zhong S,, Jaeger G,, Mongan NP, Hejátko J, Helariutta Y,, Fray RG (2017) Identification of factors required for m6 A mRNA methylation in Arabidopsis reveals a role for the conserved E3 ubiquitin ligase HAKAI. New Phytol. http://dx.doi.org/10.1111/nph.14586
Open Access
Rupert Fray (University of Nottingham) is the corresponding author on this global collaboration that investigates the poorly understood yet essential phenomenon of mRNA N6-adenosine methylation (m6A). They used a combination of experimental techniques to identify a range of proteins that are necessary for this process. These proteins include the E3 ubiquitin ligase HAKAI that, when its expression is reduced, causes a range of phenotypes, including aberrant root vascular formation. The targets of the HAKAI E3 ligase are still to be determined but the authors suspect that this type of interaction will have relevance across eukaryotic species.
Huh SU, Cevik V, Ding P, Duxbury Z, Ma Y, Tomlinson L, Sarris PF, Jones JDG (2017) Protein-protein interactions in the RPS4/RRS1 immune receptor complex. PLoS Pathog.
http://dx.doi.org/10.1371/journal.ppat.1006376 Open Access
Jonathan Jones (The Sainsbury Laboratory, Norwich) leads this UK-funded study that includes collaborators from Bath and Exeter and looks into the function of the RPS4-RRS1 immune signaling complex. During the course of the paper they define the sub-cellular binding relationships between plant proteins RPS4, RRS1, EDS1 along with the pathogen effector AvrRps4. Furthermore they show that these protein interactions differently interact with PAD4 or SAG101. The authors demonstrate that this immune complex is highly dynamic during effector recognition and that altered proportions of each member disrupts the defence response.
Shen Q, Bourdais G, Pan H, Robatzek S, Tang D (2017) Arabidopsis glycosylphosphatidylinositol-anchored protein LLG1 associates with and modulates FLS2 to regulate innate immunity. PNAS http://dx.doi.org/10.1073/pnas.1614468114 Open Access
Silke Robatzek (The Sainsbury Laboratory, Norwich) is a co-author on this Chinese-led study that investigates the role of the FERONIA signaling complex in the response to pathogen PAMPs. They show that LORELEI-LIKE GPI-ANCHORED PROTEIN 1 (LLG1) is a FERONIA co-receptor and that plants deficient in llg1 are more susceptible to various pathogens even though these plants do not show general growth defects. Overall the authors show that as a coreceptor of FERONIA, LLG1 plays a central role in many PAMP-dependent signaling pathways and is a candidate for future research in this area.
Vincent TR, Avramova M, Canham J, Higgins P, Bilkey N, Mugford ST, Pitino M, Toyota M, Gilroy S, Miller TJ, Hogenhout S, Sanders D (2017) Interplay of Plasma Membrane and Vacuolar Ion Channels, Together with BAK1, Elicits Rapid Cytosolic Calcium Elevations in Arabidopsis during Aphid Feeding. Plant Cell. http://dx.doi.org/10.1105/tpc.17.00136 Open Access
Dale Sanders and GARNet committee member Saskia Hogenhout are corresponding authors on this study that includes researchers from the JIC and the University of Wisconsin. This research focused on the role of calcium as a signal during the response to biotic stress. They combined a fluorescent calcium biosensor (GCaMP3) during aphid predation experiments. They detected elevated calcium levels that coincided with aphid probing of leaf epidermal and mesophyll cell layers. They used the power of Arabidopsis genetics to determine that a number of known signaling molecules were involved in this process, allowing them to link biotic predation, the defence response and cellular calcium movement within a single signaling network.