The latest GARNet Research Roundup includes two papers led by Cyril Zipfel from The Sainsbury lab, Norwich (who has since moved his lab to the University of Zurich). The first paper demonstrates the potential for cross-species strategies for developing disease resistance whilst the second is a phosphoproteomic dissection of the BAK1 immune co-receptor. Third is work from the lab of Liam Dolan (University of Oxford) that has discovered a novel type of regulation for RSL Class I bHLH transcription factors in Marchantia. Finally is research from Paul Dupree’s lab in Cambridge that investigates the structure of galactoglucomannan polysaccharides in the Arabidopsis cell wall.
Pfeilmeier S, George J, Morel A, Roy S, Smoker M, Stransfeld L, Downie JA, Peeters N, Malone JG, Zipfel C (2018) Expression of the Arabidopsis thaliana immune receptor EFR in Medicago truncatula reduces infection by a root pathogenic bacterium, but not nitrogen-fixing rhizobial symbiosis. Plant Biotechnol J. doi: 10.1111/pbi.12999
Open Access
Sebastian Pfeilmeier and Jeoffrey George lead this work from the labs of Jacob Malone and Cyril Zipfel at the John Innes Centre and the Sainsbury lab, Norwich. In this study they have expressed the Arabidopsis PRR ELONGATION FACTOR-THERMO UNSTABLE RECEPTOR (EFR) immune reception in Medicago truncatula. They show that these transgenic plants remain able to form root nodules with the bacterial symbiont Sinorhizobium meliloti. However they are resistant to the bacterial pathogen Ralstonia solanacearum. This study shows the potential of cross-species approaches to develop broad-spectrum pathogen resistance. It will be interesting to learn more about future developments in this area.
Perraki A, DeFalco TA, Derbyshire P, Avila J, Séré D, Sklenar J, Qi X, Stransfeld L, Schwessinger B, Kadota Y, Macho AP, Jiang S, Couto D, Torii KU, Menke FLH, Zipfel C (2018) Phosphocode-dependent functional dichotomy of a common co-receptor in plant signalling. Nature doi: 10.1038/s41586-018-0471-x
This second study from the lab of Cyril Zipfel is led by Artemis Perraki and includes wide range of collaborators from across the globe. They have used phosphoproteomics and targeted mutagenesis to perform a detailed characterisation of the immune co-receptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1). This protein interacts with many leucine-rich repeat receptor kinases (LRR-RKs) yet they find that specific phosphosites discriminate between subsets of BAK1 functions that are linked to hormone or immune signaling. This study reveals new complexity in the regulation of this multi-facted protein and has broad importance regarding our understanding of how the phosphocode allows separation of the different signaling outputs.
Honkanen S, Thamm A, Arteaga-Vazquez MA, Dolan L (2018) Negative regulation of conserved RSL class I bHLH transcription factors evolved independently among land plants. Elife. doi: 10.7554/eLife.38529
Open Access
This study looks at the role of RSL class I basic helix-loop-helix transcription factors in the control of development in the lower plant Marchantia polymorpha. This work is led by Suvi Honkanen from Liam Dolan’s lab at the University of Oxford. In Arabidopsis RSL genes are negatively regulated by the GLABRA transcription factor yet in this study the authors identify a novel microRNA-based regulatory mechanism. Although RSL1 class I genes are evolutionarily conserved across land plants the miRNA regulatory module is only present in Marchantia, demonstrating that conserved genes can have divergent modes of regulation to control lineage-specific developmental requirements
Yu L, Lyczakowski JJ, Pereira CS, Kotake T, Yu X, Li A, Mogelsvang S, Skaf MS, Dupree P (2018) The patterned structure of galactoglucomannan suggests it may bind to cellulose in seed mucilage. Plant Physiol. doi: 10.1104/pp.18.00709
Open Access
This work is led by Li Yu from the lab of Paul Dupree at the University of Cambridge. They have investigated the detailed structure of mannose-based (mannan) polysaccharides within the Arabidopsis cell wall. These have previously been shown to be important in maintaining seed mucilage architecture, which has a glucose-mannose (glucomannan) backbone. The authors assess the contribution of the Cellulose Synthase-Like A2 (CSLA2) and Mannan α-Galactosyl Transferase 1 (MAGT1) enzymes in the construction and decoration of a galactoglucomannan backbone and provide data for molecular stimulations to predict as to how these might interact with cellulose microfibrils.
