ARABIDOPSIS RESEARCH ROUND-UPARABIDOPSIS RESEARCH ROUND-UP

28th Oct 2013

There’s been little evidence of Storm St. Jude here at GARNet Towers, so happily we’re still able to bring you this week’s Arabidopsis Research Round-up!

 

  • San-Bento R, Farcot E, Galletti R, Creff A & Ingram G. Epidermal identity is maintained by cell-cell communication via a universally active feedback-loop in Arabidopsis thaliana. The Plant Cell, 21 October 2013. DOI: 10.1111/tpj.12360

Plant scientists from the Universities of Lyon, Nottingham and Edinburgh add to our understanding of the regulation of the transcription factors ATML1 and PDF2. These two proteins are known to be associated with epidermal cell fate specification in Arabidopsis embryos, but their relationship with cell-cell signalling pathways is unclear. Here it is shown that the receptor kinase ACR4 positively affects the expression of ATML1 and PDF2 in seedlings, whereas complexes containing ATML1 and PDF2 directly and negatively affect both their own expression and that of ACR4.

 

  • Forde BG. Glutamate signalling in roots. Journal of Experimental Botany, 22 October 2013. DOI: 10.1093/jxb/ert335.

In this J Exp Bot review, Lancaster University’s Brian Forde discusses recent advances in our understanding of the role of glutamate as a signalling molecule in plants. He particularly examines recent genetic evidence for a glutamate signalling pathway in roots.

 

  • Peret B, Middleton AM, French AP, et al. Sequential induction of auxin efflux and influx carriers regulates lateral root emergence. Molecular Systems Biology, 22 October 2013. DOI: 10.1038/msb.2013.43.

GARNet committee member Malcolm Bennett and colleagues from the University of Nottingham collaborated with plant scientists from France, Finland, Belgium, Sweden and the US to produce this Molecular Systems Biology paper. First, it was identified that auxin is transported from the lateral root primordia towards the outer tissues; here it triggers cell separation by inducing the auxin influx carrier LAX3 and cell-wall enzymes. A mathematical model was then developed to understand more about the regulatory network and direct this experiment. It was predicted that an efflux carrier would also be required; this was later identified as PIN3, with PIN3 and LAX3 needing to be induced consecutively to prevent LAX3 from being transiently expressed in multiple cell files.

 

  • Bartels S, Lori M, Mbengue M, van Verk M, Klauser D, Hander T, Boni R, Robatzek S & Boller T. The family of AtPeps and their precursors in Arabidopsis: differential expression and localization but similar induction of pattern-triggered immune responses. Journal of Experimental Botany, 22 October 2013. DOI: 10.1093/jxb/ert330.

Another offering from the Journal of Experimental Botany; this time involving a team of Swiss researchers, Marcel van Verk from Utrecht University in the Netherlands, and the Sainsbury Laboratory’s Malick Mbengue. The team looked at the role of a group of endogenous danger peptides called AtPeps in Arabidopsis thaliana, which are encoded in the C termini of the PROPEP precursors. It was found that, despite the redundancy of the AtPeps, PROPEPs in fact fall into two distinct groups. Whereas different AtPeps work in a similar manner to activate plant defense-related responses, expression of their associated PROPEPs seems to correlate with a variety of functions including plant defense, reproduction, and localization to the cytosol and tonoplast.

 

  • Haydon MJ, Mielczarek O, Robertson FC, Hubbard KE & Webb AAR. Photosynthetic entrainment of the Arabidopsis thaliana circadian clock. Nature, 23 October 2013. DOI: 10.1038/nature12603.

In this Nature paper, the Webb lab at the University of Cambridge demonstrates that rhythmic, endogenous sugar signals can entrain circadian rhythms in Arabidopsis thaliana. When photosynthesis was inhibited, it was shown that endogenous oscillations in sugar levels provided metabolic feedback to the circadian oscillator. Knocking out the PSEUDO-RESPONSE REGULATOR 7 (PRR7) gene gave evidence that this gene confers sensitivity to the effects of sucrose on the circadian period, and shows that metabolism has a crucial role in circadian clock regulation.

 

  • Oh SA, Bourdon V, Dickinson HG, Twell D & Park SK. Arabidopsis fused kinase TWO-IN-ONE dominantly inhibits male meiotic cytokinesis. Plant Reproduction, October 2013. DOI: 10.1016/10.1007/s00497-013-0235-6.

This collaboration between the Universities of Leicester and Oxford, and Vertex Pharmaceuticals in Oxford, reveals that Arabidopsis Fused kinase TWO-IN-ONE (TIO) is involved in the regulation of male meiotic cytokinesis. More specifically, it was found that transgenic Arabidopsis plants that overexpress TIO tend to have enlarged pollen grains, which arise from incomplete cytokinesis during male meiosis, as well as sporophytic abnormalities that suggest polyploidy. The results provide evidence that TIO dominantly inhibits TIO in a dosage-dependent manner.