This bumper GARNet Research Roundup begins with two sets of papers in related areas. First are three papers that investigate the biology of plasmodesmatata. These include work from the Faulkner lab at the JIC, the Band lab at Nottingham and a broad European collaboration that includes co-authors from Durham, Cambridge and St Andrews.
The second set of two papers features work on different species of Kalanchoë, which is a key model for the study of CAM. This research is from the Hartwell lab in Liverpool and the Borland lab in Newcastle.
The fifth paper is from RHUL and looks at the relationship between nucleus and chloroplast signaling. The sixth paper is from QMUL and introduces research suggesting that a rethink is needed in our understanding of the relationship between chloroplast movement and photoprotection.
The next paper is from the University of the West of England and looks at the effect of ionising radiation on multiple generation of Arabidopsis growth whilst the eighth paper investigates the relationship between starch degradation and stomatal movements in guard cells and includes co-authors from Essex and Glasgow.
The next two papers include research undertaken in Cambridge; firstly looking at the integration of signalling between karrikin and strigolactone signaling in rice and secondly identifying a novel mRNA thermoswitch that controls thermomorphogenesis.
The next paper is a pan-European project led from Nottingham that has characterised the role of the CEP5 peptide during regulation of osmostic stress, drought and auxin signaling.
The twelveth paper is from the University of Warwick and also looks at the auxin response, this time during senescence. The next paper as well includes co-authors from Warwick in a study that investigates the global regulatory role for the histone acetyltransferase GCN5.
The penultimate paper includes co-authors from Norwich Research Park looks at the evolution of immune NLR signaling between closely related species. The final paper includes Patrick Hussey from Durham as a co-author in a Spanish study that identifies an uncharacterized compartment of the plant vacuolar trafficking pathway.
Cheval C, Samwald S, Johnston MG, de Keijzer J, Breakspear A, Liu X, Bellandi A, Kadota Y, Zipfel C, Faulkner C (2020) Chitin perception in plasmodesmata characterizes submembrane immune-signaling specificity in plants. Proc Natl Acad Sci U S A. 2020 Apr 28;117(17):9621-9629. doi: 10.1073/pnas.1907799117 Open Access
Cecilia Cheval, Sebastian Samwald and Matthew Johnston are co-first authors on this work from the Faulkner lab at the John Innes Centre. They looked at a plasmodesmata-localised plasma membrane microdomain, which hosts specific receptors and responses. They showed that immune chitin signalling requires the plasmodesmal PM localised LYM2 and LYK4 proteins. Overall this demonstrates that distinct membrane domains can integrate common signals to produce a localized response.
Brault ML, Petit JD, Immel F, Nicolas WJ, Glavier M, Brocard L, Gaston A, Fouché M, Hawkins TJ, Crowet JM, Grison MS, Germain V, Rocher M, Kraner M, Alva V, Claverol S, Paterlini A, Helariutta Y, Deleu M, Lins L, Tilsner J, Bayer EM (2020) Multiple C2 domains and transmembrane region proteins (MCTPs) tether membranes at plasmodesmata. EMBO Rep. 2019 Aug;20(8):e47182. doi: 10.15252/embr.201847182 Open Access
Marie Brault works with Emmualle Bayer is first author on this French-led pan-European study that includes co-authors from Durham, Cambridge and St Andrews. They investigate the plasmodesmal plasma membrane and show that Multiple C2 domains and transmembrane region proteins (MCTP) are needed to tether ER-PM linkages at this location. They show Atmctp3/Atmctp4 loss of function double mutants have plant developmental defects demonstrating that MCTPs also play a significant role in cell-to-cell signalling.
Mellor NL, Voß U, Janes G, Bennett MJ, Wells DM, Band LR (2020) Auxin fluxes through plasmodesmata modify root-tip auxin distribution. Development. doi: 10.1242/dev.181669 Open Access
Nathan Mellor leads this research from the University of Nottingham that has developed a model to explain auxin movement around the Arabidopsis root tip. They propose that carrier mediated movement is not sufficient foir this and that there must be a symplastic route via plasmodesmata. This introduces plasmodesmata as playing a key role in hormone signaling.
GARNet committee member Yoselin Benitez-Alfonso discusses her labs work on plasmodesmata in the first #GARNetPresents webinar
Boxall SF, Kadu N, Dever LV, Kneřová J, Waller JL, Gould PJD, Hartwell J (2020) Kalanchoë PPC1 Is Essential for Crassulacean Acid Metabolism and the Regulation of Core Circadian Clock and Guard Cell Signaling Genes. Plant Cell. doi: 10.1105/tpc.19.00481
Susie Boxall leads this study from the Hartwell lab at the University of Liverpool in which they investigate the role of the phosphoenolpyruvate carboxylase gene in the CAM-plant Kalanchoë laxiflora. They use RNA interference to silence the PPC1 gene and show that these transgenic plants have defects in guard cell signaling and regulation of the circadian clock. These findings provide direct evidence that the regulatory patterns of key guard cell signaling genes are linked with the characteristic inverse pattern of stomatal opening and closing during CAM.
Abraham PE, Hurtado Castano N, Cowan-Turner D, Barnes J, Poudel S, Hettich R, Flütsch S, Santelia D, Borland AM (2020) Peeling back the layers of Crassulacean acid metabolism: functional differentiation between Kalanchoë fedtschenkoi epidermis and mesophyll proteomes. Plant J. doi: 10.1111/tpj.14757 Open Access
Paul Abraham is first author on this work from the Borland lab at the University of Newcastle. They are working with the CAM species Kalanchoë fedtschenkoi and here perform a large-scale proteomics analysis of the epidermis and mesophyll cell layers. This reveals that different proteins and biological processes are enriched in each layer, showing how plants adapt to hot and dry environments by modifying leaf physiology for improved plant sustainability.
Loudya N, Okunola T, He J, Jarvis P, López-Juez E (2020) Retrograde signalling in a virescent mutant triggers an anterograde delay of chloroplast biogenesis that requires GUN1 and is essential for survival Philos Trans R Soc Lond B Biol Sci. 2020;375(1801):20190400. doi:10.1098/rstb.2019.0400 Open Access
Naresh Loudya from Royal Hollaway University of London is first author on this work that investigates the relationship between nucleus and chloroplast gene expression in the control of chloroplast biogenesis. They analyse the cue8 mutant that shows differential changes in the activity of plastid-encoded and nucleus-encoded polymerases.
Naresh discussed this paper on the GARNet Community podcast.
Wilson S, Ruban AV (2020) Rethinking the influence of chloroplast movements on non-photochemical quenching and photoprotection. Plant Physiol. 2020 May 13. pii: pp.00549.2020. doi: 10.1104/pp.20.00549 Open Access
Sam Wilson is first author on this work from the Ruban lab at the Queen Mary University of London. In this study they have assessed the relationship between blue light induced chloroplast relocation and high-light tolerance. Their data argues against the existence of a chloroplast movement-dependent component of the non-photochemical quenching (NPQ) respose. Therefore the authors suggest that thinking on the influence of chloroplast movements on photoprotection should be reevaluated.
Caplin NM, Halliday A, Willey NJ (2020) Developmental, Morphological and Physiological Traits in Plants Exposed for Five Generations to Chronic Low-Level Ionising Radiation. Front Plant Sci. doi: 10.3389/fpls.2020.00389 Open Access
Nicol Caplin is first author on this research from the University of the West of England that looked at the effects of ionising radiation (IR) on seven generations of Arabidopsis growth. They found that although chronic exposure to IR caused some individual trait changes, these are not carried across generations at the population level but still call for more research in this area to be sure of the current regulations provided by the International Commission for Radiological Protection (ICRP).
Flütsch S, Wang Y, Takemiya A, Vialet-Chabrand SR, Klejchova M, Nigro A, Hills A, Lawson T, Blatt MR, Santelia D (2020) Guard Cell Starch Degradation Yields Glucose for Rapid Stomatal Opening in Arabidopsis. Plant Cell. doi: 10.1105/tpc.18.00802
This Swiss-led study has Sabrina Flütsch as first author and co-authors from Essex and Glasgow. They looked at the integration of starch degradation in guard cells with the kinetics of stomatal reopening. The timing of rapid stomatal unopening was unchanged in starch degrading mutants but there were alterations in slower responses, most likely due to alterations in the composition of guard cell starch metabolites.
Choi J, Lee T, Cho J, Servante EK, Pucker B, Summers W, Bowden S, Rahimi M, An K, An G, Bouwmeester HJ, Wallington EJ, Oldroyd G, Paszkowski U (2020) The negative regulator SMAX1 controls mycorrhizal symbiosis and strigolactone biosynthesis in rice. Nat Commun. doi: 10.1038/s41467-020-16021-1 Open Access
This research is led from the Paszkowski lab at the University of Cambridge by Jeongmin Choi. They have found that the rice ortholog of Arabidopsis Suppressor of MAX2-1 plays a novel role to link the pre-symbiotic perception of arbuscular mycorrhizal fungi with karrikin and strigolactone signaling. This response functions through a modification of the D14L signalling pathway.
Chung BYW, Balcerowicz M, Di Antonio M, Jaeger KE, Geng F, Franaszek K, Marriott P, Brierley I, Firth AE, Wigge PA (2020) An RNA thermoswitch regulates daytime growth in Arabidopsis. Nat Plants. doi: 10.1038/s41477-020-0633-3
This Wigge lab-led collaboration includes Betty Chung as first author and investigate the role of the PIF7 messenger RNA as a thermoswitch that activates the thermomorphogenesis pathway. This is controlled by the formation of an RNA hairpin within the mRNA and they show that this mechanism is conserved so controls translation of other mRNAs, enabling the plant to respond and adapt rapidly to high temperatures.
Smith S, Zhu S, Joos L, Roberts I, Nikonorova N, Vu LD, Stes E, Cho H, Larrieu A, Xuan W, Goodall B, van de Cotte B, Waite JM, Rigal A, R Harborough SR, Persiau G, Vanneste S, Kirschner GK, Vandermarliere E, Martens L, Stahl Y, Audenaert D, Friml J, Felix G, Simon R, Bennett M, Bishopp A, De Jaeger G, Ljung K, Kepinski S, Robert S, Nemhauser J, Hwang I, Gevaert K, Beeckman T, De Smet I (2020) The CEP5 peptide promotes abiotic stress tolerance, as revealed by quantitative proteomics, and attenuates the AUX/IAA equilibrium in Arabidopsis. Mol Cell Proteomics. 2020 May 13. pii: mcp.RA119.001826. doi: 10.1074/mcp.RA119.001826 Open Access
Stephanie Smith at the University of Nottingham is first author on this collaboration between researchers in 8 different countries. They use quantitative proteomics to assess the role of the CEP8 peptide in the response to osmotic and drought stress and in the control of auxin signaling.
Gören-Sağlam N, Harrison E, Breeze E, Öz G, Buchanan-Wollaston V (2020) Analysis of the impact of indole-3-acetic acid (IAA) on gene expression during leaf senescence in Arabidopsis thaliana. Physiol Mol Biol Plants. doi: 10.1007/s12298-019-00752-7
Nihal Gören-Sağlam is first author on this study from the University of Warwick in which they investigate the role of externally applied auxin on senescence in Arabidopsis thaliana. They show that PSII activity, as a determinant of chlorophyll fluorescence, declined after auxin treatment and that this response changed across different leaves.
Kim S, Piquerez SJM, Ramirez-Prado JS, Mastorakis E, Veluchamy A, Latrasse D, Manza-Mianza D, Brik-Chaouche R, Huang Y, Rodriguez-Granados NY, Concia L, Blein T, Citerne S, Bendahmane A, Bergounioux C, Crespi M, Mahfouz MM, Raynaud C, Hirt H, Ntoukakis V, Benhamed M (2020) GCN5 modulates salicylic acid homeostasis by regulating H3K14ac levels at the 5′ and 3′ ends of its target genes. Nucleic Acids Res. doi: 10.1093/nar/gkaa369 Open Access
This French-led study includes Soonkap Kim as first author and co-authors from the University of Warwick. They analysed the role of the histone acetyltransferase GCN5 in global control of gene expression. They used several methodologies (ATAC-seq, ChIP-seq and RNA-seq) to assess the effect of GCN5 loss-of-function on the expression and epigenetic regulation of its target genes.
Baggs E, Monroe JG, Thanki AS, O’Grady R, Schudoma C, Haerty W, Krasileva KV (2020) Convergent Loss of an EDS1/PAD4 Signaling Pathway in Several Plant Lineages Reveals Co-evolved Components of Plant Immunity and Drought Response. Plant Cell. doi: 10.1105/tpc.19.00903 Open Access
This research is led by Erin Baggs in the Krasileva lab at the University of California Berkeley and includes co-authors from Norwich Research Park. They assessed the variation in nucleotide-binding leucine-rich repeat receptors (NLRs) involved in plant immunity, focusing on closely related species that have different NLR compositions. Loss of NLRs corresponds to other changes in downstream immune signaling complexes. This excellent extensive multi-omic analysis provides evolutionary evidence for the rewiring of immunity in some plant lineages.
Delgadillo MO, Ruano G, Zouhar J, Sauer M, Shen J, Lazarova A, Sanmartín M, Lai LTF, Deng C, Wang P, Hussey PJ, Sánchez-Serrano JJ, Jiang L, Rojo E (2020) MTV proteins unveil ER- and microtubule-associated compartments in the plant vacuolar trafficking pathway. Proc Natl Acad Sci U S A. doi: 10.1073/pnas.1919820117
María Otilia Delgadillo is first author on this Spanish-led study that includes Patrick Hussey from Durham as a co-author. The study identifies 13 components of the vacuolar trafficking machinery through a genetic screen for mutants that abnormally secrete the synthetic vacuolar cargo VAC2. Eight of these components localize at the interface between the trans-Golgi network (TGN) and the multivesicular bodies (MVBs), which excitingly reveals a previously uncharacterized compartment of the plant vacuolar trafficking pathway.
