14th Nov 2016

This weeks Arabidopsis Research Roundup is led by a manuscript from Tom Bennett and Ottoline Leyser that looks at strigolactone signaling for which Tom provides a brief audio description. Elsewhere Verena Kreichbaumer (Oxford Brookes) is a co-author on a study that looks into cytokinin control of auxin biosynthesis and Mike Blatt’s lab at the University of Glasgow continue to elucidate the role of SNARE proteins in vesicle formation. The penultimate paper includes Peter van Esse as a co-author of a study into the role of SERK proteins in the control of different signaling pathways. Finally Pierre Petriacq (University of Sheffield) is the lead-author on a short communication that describes the control of cytosolic calcium by NAD.

Tom Bennett, Yueyang Liang, Madeleine Seale, Sally Ward, Dörte Müller, Ottoline Leyser (2016) Strigolactone regulates shoot development through a core signalling pathway Biology Open Open Access

Tom Bennett is the lead author of this manuscript that results from work conducted in Ottoline Leysers lab at SLCU. Tom has recently started his own lab at the University of Leeds and kindly provides an audio description of this paper that describes their attempts to define determinants of the strigolactone signalling pathway. Initially they define a set of strigolactone responses by assessing multiple aerial phenotypes and show that the degradation of neither BES1 or the DELLA proteins are directly influenced by SCF-MAX2 complex. Importantly they demonstrate that the degradation of SMXL6-related proteins is a key step in strigolactone signalling and that it occurs via the Arabidopsis D14 protein. Finally they show that degradation of SMXL6-related proteins may regulate activity of the BRANCHED1 transcription factor and the PIN-FORMED1 auxin efflux carrier during shoot branching.

Di DW, Wu L, Zhang L, An CW, Zhang TZ, Luo P, Gao HH, Kriechbaumer V, Guo GQ (2016) Functional roles of Arabidopsis CKRC2/YUCCA8 gene and the involvement of PIF4 in the regulation of auxin biosynthesis by cytokinin. Sci Rep. Open Access

Verena Kreichbaumer (Oxford Brookes University) is a co-author on this paper that aims to tease out the relationship between cytokinin and auxin biosynthesis. They isolate a cytokinin root curling mutant, ckrc2, that is allelic to the YUC8 auxin biosynthetic gene. CKRC2/YUC8 is the rate limiting enzyme in the conversion of indole-2-pyruvic acid to IAA and the gene is induced by cytokinin, a process that requires the transcription factor phytochrome-interacting factor 4 (PIF4). These findings add information to our knowledge of how cytokinin signaling controls auxin biosynthesis.

Zhang B, Karnik R, Waghmare S, Donald NA, Blatt MR (2016) VAMP721 conformations unmask an extended motif for K+ channel binding and gating control. Plant Physiol.

Open Access

Mike Blatt (University of Glasgow) is the corresponding author on this study that adds to his labs work investigating the factors that control activity of SNARE proteins, which play a major role in intracellular membrane fusion. They show that the VAMP721 protein regulates the function of the KAT1 K+ channel by binding via its SNARE domain, an interaction that opposes VAMP721 binding to the SNARE SYP21.

van Esse GW, Ten Hove CA, Guzzonato F, van Esse HP, Boekschoten M, Ridder L, Vervoort J, de Vries SC (2016) Transcriptional analysis of serk1 and serk3 receptor-like kinase mutants. Plant Physiol. http:/​/​dx.​doi.​org/​10.​1104/​pp.​16.​01478

This Dutch-led study includes Peter Van Esse from The Sainsbury Lab in Norwich and attempts to decipher the role of Somatic Embryogenesis Receptor like Kinases (SERKs) in brassinosteroid (BR) signalling. They performed a global expression analysis on serk1serk3 double mutant plants and uncovered about 700 differentially regulated genes that, perhaps unsurprisingly, were involved in multiple biological processes. The largest proportion of these genes were either related to BR signalling or primary and secondary metabolism. Furthermore they demonstrated that the serk mutants show some redundancy as many of the serk1serk3 responses are recapitulated in serk3-2 single mutants.

Pétriacq P, Tcherkez G, Gakière B (2016) Pyridine nucleotides induce changes in cytosolic pools of calcium in Arabidopsis. Plant Signal Behav.

Pierre Petriacq is a new research fellow at the University of Sheffield and is the lead author of this UK-French-Australian short communication that looks at how the pyridine nucleotide NAD impacts the cytosolic calcium pool. This is a follow up on a recent study that investigated the role of NAD in determination of multiple arms of the plant defence response.