GARNet Research Roundup: August 16th 2019

This holiday-time edition of the GARNet research roundup begins with two papers that include the late Ian Moore from the University of Oxford as a co-author. The first looks at the role of RAB-A5c in the control of cellular growth anisotropy whilst the second characterises the Transport Protein Particle II (TRAPPII) complex.

The third paper is a UK-wide collaboration that assesses the role of UVA signaling on stomatal development. Next is a paper from Cambridge and the JIC that has identified the TAF4b protein as a novel regulator of meiotic crossovers.

The fifth paper is from the University of York and characterizes a role for cis-12-oxo-phytodienoic acid (OPDA) during seed germination.

The next three papers feature scientists from the University of Leeds in research that investigates 1, a peroxisomal ABC transporter; 2, the role of LRR-RLKs in plasmodesmata development and 3, the cell wall characteristics of banana and mango fruit.

The ninth paper is from the University of Edinburgh and investigates the role of S-nitrosylation in the control of SUMO conjugation.

The next two papers include Steve Penfield at the JIC as a corresponding author; the first looks at the role of endosperm-expressed transcriptional factors during seed dormancy and the second, in collaboration with researchers at the University of Warwick, identifies novel QTLs involved in seed dormancy.

The penultimate study is from Lancaster and presents a surprising outcome resulting from the overexpression of the wheat CA1Pase gene. The final paper includes Alison Tidy and Zoe Wilson from University of Nottingham as co-authors on a study that looks at male fertility in Arabidopsis.


Kirchhelle C, Garcia-Gonzalez D, Irani NG, Jérusalem A, Moore I (2019) Two mechanisms regulate directional cell growth in Arabidopsis lateral roots. Elife. pii: e47988. doi: 10.7554/eLife.47988

Open Access

Charlotte Kirchhelle leads this work that was conducted in the lab of the late Ian Moore at the University of Oxford. She investigates the role of the plant-specific small GTPase RAB-A5c during growth anisotropy in lateral roots, which involves coordinated orientations of cellulose microfibrils (CMFs) and by cortical microtubules (CMTs). They identify RAB-A5c dependent and independent mechanisms to control cellular growth anisotropy in this growing tissue.

From https://elifesciences.org/articles/47988

Kalde M, Elliott L, Ravikumar R, Rybak K, Altmann M, Klaeger S, Wiese C, Abele M, Al B, Kalbfuß N, Qi X, Steiner A, Meng C, Zheng H, Kuster B, Falter-Braun P, Ludwig C, Moore I, Assaad FF (2019) Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis. Plant J. doi: 10.1111/tpj.14442

This German-led study includes Monika Kalde from the University of Oxford as first author as well Ian Moore as co-author. They characterize the components and function of the Transport Protein Particle II (TRAPPII) complex. TRAPPII plays multiple roles in intra-cellular transport and this study identified 13 subunits, including several that were previously uncharacterised.


Isner JC, Olteanu VA, Hetherington AJ, Coupel-Ledru A, Sun P, Pridgeon AJ, Jones GS, Oates M, Williams TA, Maathuis FJM, Kift R, Webb AR, Gough J, Franklin KA, Hetherington AM (2019). Short- and Long-Term Effects of UVA on Arabidopsis Are Mediated by a Novel cGMP Phosphodiesterase. Curr Biol.29(15):2580-2585.e4. doi: 10.1016/j.cub.2019.06.071

Open Access

Jean-Charles Isner is the first author on this collaboration between labs in Bristol, York, Oxford and Cambridge. They show that UVA radiation (which represents 95% of the UV radiation reaching earth) inhibits stomatal opening through a process that involves a reduction in the cytosolic level of cGMP. The AtCN-PDE1 gene (a cGMP-activated phosphodiesterase) is needed to decrease cGMP levels in Arabidopsis. This response is present across the tree of life except in metazoans. They show AtCN-PDE1 is needed for the UVA response and that prolonged UVA exposure causes increased growth yet reduced water use efficiency.


Lawrence EJ, Gao H, Tock AJ, Lambing C, Blackwell AR, Feng X, Henderson IR (2019) Natural Variation in TBP-ASSOCIATED FACTOR 4b Controls Meiotic Crossover and Germline Transcription in Arabidopsis. Curr Biol. pii: S0960-9822(19)30844-9. doi: 10.1016/j.cub.2019.06.084

Open Access

This work from Ian Henderson’s lab in Cambridge and Xiaoqi Feng’s lab at the JIC is led by Emma Lawrence and isolates a novel modifier of meiotic crossover frequency, TBP-ASSOCIATED FACTOR 4b (TAF4b), which encodes a subunit of the RNA polymerase II general transcription factor TFIID. They show TAF4b expression is enriched in meiocytes, compared to the more general expression of its paralog TAF4. Ultimately they reveal TAF4b drives a novel mode of meiotic recombination control through its activity as a general transcription factor.


Barros-Galvão T, Dave A, Cole A, Harvey D, Langer S, Larson TR, Vaistij FE, Graham IA (2019) cis-12-oxo-phytodienoic acid represses Arabidopsis thaliana seed germination in shade light conditions. J Exp Bot. pii: erz337. doi: 10.1093/jxb/erz337

Open Access

Thiago Barros-Galvão is first author on this study from Ian Graham’s lab at the University of York. They investigate how the jasmonic acid pre-cursor cis-12-oxo-phytodienoic acid (OPDA) contributes to control of seed germination, particularly under shade conditions. OPDA acts through the activity of the transcription factor MOTHER-OF-FT-AND-TFL1 (MFT).

From https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/erz337/5536641

Carrier DJ, van Roermund CWT, Schaedler TA, Rong HL, IJlst L, Wanders RJA, Baldwin SA, Waterham HR, Theodoulou FL, Baker A (2019) Mutagenesis separates ATPase and thioesterase activities of the peroxisomal ABC transporter, Comatose. Sci Rep. 9(1):10502. doi: 10.1038/s41598-019-46685-9

Open Access

Alison Baker at the University of Leeds is the corresponding author of this UK, Dutch collaboration that includes David Carrier as first author. They characterise the peroxisomal ABC transporter, Comatose (CTS) through mutagenesis of key residues responsible for the proteins intrinsic acyl-CoA thioesterase (ACOT) activity. Ultimately they show that ACOT activity depends of endogenous ATPase activity but that these activities could be functional separated by mutagenesis of key residues.


Grison M, Kirk P, Brault M, Wu XN, Schulze WX, Benitez-Alfonso Y, Immel F, Bayer EMF (2019). Plasma membrane-associated receptor like kinases relocalize to plasmodesmata in response to osmotic stress. Plant Physiol. pii: pp.00473.2019. doi: 10.1104/pp.19.00473

Open Access

GARNet advisory committee member Yoselin Benitez-Alfonso and members of her research group are co-authors on the next two studies. This work is led by Magali Grison in Emmanuelle Bayer’s lab in Bordeaux. They show that the PM-localised Leucine-Rich-Repeat Receptor-Like-Kinases (LRR-RLKs), QSK1 and IMK2 relocate and cluster to the plasmodesmata under osmotic stress conditions. Through a variety of assays that focuses on QSK1 the authors show that reorganisation of RLKs can be important for the regulation of callose deposition at plasmodesmata and under osmotic stress this can have a functional effect on lateral root development.


Rongkaumpan G, Amsbury S, Andablo-Reyes E, Linford H, Connell S, Knox JP, Sarkar A, Benitez-Alfonso Y, Orfila C (2019) Cell Wall Polymer Composition and Spatial Distribution in Ripe Banana and Mango Fruit: Implications for Cell Adhesion and Texture Perception. Front Plant Sci. 10:858. doi: 10.3389/fpls.2019.00858

Open Access

Ganittha Rongkaumpan is first author on this interdisciplinary collaborative research from multiple departments at the University of Leeds. They characterise the composition of the cell wall in two fruits, banana and mango, which soften during ripening. The authors compared structural information, obtained using Atomic Force Microscopy and biochemical analysis, with data from rheology and tribology assays to understand why these fruits feel different in the mouth during ingestion.


Skelly MJ, Malik SI, Le Bihan T, Bo Y, Jiang J, Spoel SH, Loake GJ (2019) A role for S-nitrosylation of the SUMO-conjugating enzyme SCE1 in plant immunity Proc Natl Acad Sci U S A. pii: 201900052. doi: 10.1073/pnas.1900052116

Michael Skelly from the University of Edinburgh is the lead author of this study from the labs of Gary Loake and GARNet chairman Steven Spoel. They investigate the mechanism through which nitric oxide signaling after pathogen recognition stimulates inhibitory S-nitrosylation of the Arabidopsis SUMO E2 enzyme, SCE1. S-nitrosylation occurs on the evolutionary conserved Cys139 of SCE1 and they investigate the wider significant of this residue in the control of immune responses across eukaryotes.


MacGregor DR, Zhang N, Iwasaki M, Chen M, Dave A, Lopez-Molina L, Penfield S (2019) ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development. Plant J. 98(2):277-290. doi: 10.1111/tpj.14211

Open Access

Dana MacGregor (now at Rothamsted Research) leads this work from the lab of Steve Penfield at the JIC that investigates the extent of control on depth of primary dormancy that is mediated by the endosperm-expressed transcription factors ZHOUPI (ZOU) and INDUCER OF CBF EXPRESSION1 (ICE1). These effects are additive and independent of their role in endosperm development since the dormancy defect in ice1 and zou mutants can be ameliorated without altering seed morphology. They show that ICE1 acts primarily through control of ABA INSENSITIVE 3 (ABI3).


Footitt S, Walley PG, Lynn JR, Hambidge AJ, Penfield S, Finch-Savage WE (2019) Trait analysis reveals DOG1 determines initial depth of seed dormancy, but not changes during dormancy cycling that result in seedling emergence timing. New Phytol. doi: 10.1111/nph.16081

This research is a collaboration between the John Innes Centre and the Universities Liverpool and Warwick, from which Steven Footitt is first author. They used two Arabidopsis ecotypes that have differences in the timing of seedling emergence to identify new QTLs involved in depth of seed dormancy and Seedling Emergence Timing (SET). They revealed that DOG1 is important for determining depth of dormancy. In addition they identified three new SET QTLs, which are each physically close to DOG1, that play a role in the control of SET in the field.


Lobo AKM, Orr D, Gutierrez MO, Andralojc J, Sparks C, Parry MAJ, Carmo-Silva E (2019) Overexpression of ca1pase decreases Rubisco abundance and grain yield in wheat. Plant Physiol. pii: pp.00693.2019. doi: 10.1104/pp.19.00693

Open Access

This research from Lancaster Environmental Centre and their Brazilian collaborators is led by Ana Karla Lobo and demonstrates that overexpression of 2-carboxy-D-arabinitol-1-phosphate phosphatase (CA1Pase) in wheat causes a reduction in above ground biomass and compromises wheat grain yields. As CA1Pase is involved in removing inhibitors of Rubisco activity this result is contrary to the anticipated outcome. This suggests that Rubisco inhibitors might actually protect enzyme activity, thus maintaining the number of active sites that the enzyme is able to support.


Zhao SQ, Li WC, Zhang Y, Tidy AC, Wilson ZA (2019) Knockdown of Arabidopsis ROOT UVB SENSITIVE4 Disrupts Anther Dehiscence by Suppressing Secondary Thickening in the Endothecium. Plant Cell Physiol. doi: 10.1093/pcp/pcz127

Shu-Qing Zhao is the lead author on this China-UK collaboration that includes Alison Tidy and Zoe Wilson from the University of Nottingham. They show that using an artificial microRNA to reduce levels of the RUS4 gene in Arabidopsis causes a decline in male fertility. They perform a detailed analysis of the RUS4 expression module and how it impacts fertility.

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