ARABIDOPSIS RESEARCH ROUND-UPARABIDOPSIS RESEARCH ROUND-UP

8th Jan 2014

Happy New Year! There’s a lot to catch up on after the Christmas and New Year break, so here’s a bumper edition of the Arabidopsis Research Round-Up!

 

  • Westwood JH, Groen SC, Du Z, et al. A trio of viral proteins tunes aphid–plant interactions in Arabidopsis thaliana. PLOS ONE, 11 December 2013. DOI: 10.1371/journal.pone.0083066.

Scientists from the University of Cambridge and Imperial College London investigated the effects of the Fny strain of cucumber mosaic virus (Fny-CMV) on the interaction of Myzus persicae (the peach–potato aphid) with Arabidopsis thaliana Col-0. The interplay of three viral proteins (1a, 2a and 2b) were found to alter plant–aphid interactions: 2b by suppressing antiviral RNA silencing, 2a by triggering defensive signaling and increasing the accumulation of a feeding deterrent, and 1a by moderating 2b-mediated inhibition of ARGONAUTE1. 

 

  • Schnaubelt D, Queval G, Dong Y, Diaz-Vivancos P, Makgopa ME, Howell G, De Simone A, Bai J, Hannah MA and Foyer CH. Low glutathione regulates gene expression and the redox potentials of the nucleus and cytosol in Arabidopsis thaliana. Plant, Cell & Environment, 11 December 2013. DOI: 10.1111/pce.12252.

The role of reduced glutathione (GSH) in the regulation of gene expression and its influence on cellular redox potentials is known, but poorly characterised. Here, a team from the University of Leeds (with Belgian, Chinese and Spanish colleagues) show that severely reduced GSH specifically inhibits root meristem development, as seen in the GSH-deficient Arabidopsis thaliana mutant root meristemless 1-1. It is concluded that reduced GSH causes cell cycle arrest in roots but not shoots, and associated transcriptional changes are due to hormonal responses, not oxidative stress.

 

  • Block A, Toruño TY, Elowsky CG, Zhang C, Steinbrenner J, Beynon J and Alfano JR. The Pseudomonas syringae type III effector HopD1 supresses effector-triggered immunity, localizes to the endoplasmic reticulum, and targets the Arabidopsis transcription factor NTL9. New Phytologist, 12 December 2013. DOI: 10.1111/nph.12626.

Jens Steinbrenner and GARNet PI Jim Beynon, from the University of Warwick, collaborated with researchers from the University of Nebraska-Lincoln on this study of the role of the Pseudomonas syringae type III effector HopD1. It is known that HopD1 suppresses plant immunity to promote bacterial virulence, but until now this had been poorly characterised. In Arabidopsis, it was found to interact at the endoplasmic reticulum with the transcription factor NTL9, resulting in the suppression of effector-mediated plant immune responses.

 

  • Higgins JD, Wright KM, Bomblies K and Franklin C. Cytological techniques to analyze meiosis in Arabidopsis arenosa for investigating adaptation to polyploidy. Frontiers in Plant Science, 13 December 2013. DOI: 10.3389/fpls.2013.00546.

This methods paper, by plant scientists from Harvard and the University of Birmingham (UK), describes techniques to analyse male meiosis in Arabidopsis arenosa. A meiotic cytological atlas is also presented as a reference, based on findings of the differences between meiosis in diploid and autotetraploid A. arenosa.

 

  • Groen AJ, Sancho-Andres G, Breckels LM, Gatto L, Aniento F and Lilley KS. Identification of trans Golgi network proteins in Arabidopsis thaliana root tissue. Journal of Proteome Research, 17 December 2013. DOI: 10.1021/pr4008464.

A collaboration between the University of Cambridge and the University of Valencia produces this Journal of Proteome Research paper, in which a robust list of trans-Golgi network (TGN) proteins are identified. The list was compiled following analysis using both immuno isolations of the TGN proteins, and a computational, probability-based organelle proteomic technique called Localisation of Organelle Protein by Isotope Tagging (LOPIT).

 

  • Spallek T, Beck M, Ben Khaled S, Salomon S, Bourdais G, Schellmann S and Robatzek S. ESCRT-I mediates FLS2 endosomal sorting and plant immunity. PLOS Genetics, 26 December 2013. DOI: 10.1371/journal.pgen.1004035.

When activated by its ligand flagellin flg22, the plant immune receptor FLAGELLIN SENSING 2 (FLS2) is internalized by endocytosis. This paper from the Sainsbury Laboratory Cambridge and collaborators in Germany describes the previously uncharacterised role of ENDOSOMAL SORTING COMPLEX REQUIRED FOR TRANSPORT (ESCRT)-1 subunits in this internalisation process, and that they are critical for flg22-activated stomatal defences involved in plant immunity.

 

  • Trost G, V SL, Czesnick H, Lange P, Holton N, Gialvalisco P, Zipfel C, Kappel C and Lenhard M. Arabidopsis poly(A) polymerase PAPS1 limits founder-cell recruitment to organ primordial and suppresses the salicyclic acid-independent immune response downstream of EDS1/PAD4. The Plant Journal, 30 December 2013. DOI: 10.1111/tpj.12421.

Isoforms of poly(A)polymerases (PAPS) are functionally specialised in Arabidopsis thaliana. Here, scientists from the John Innes Centre and the Sainsbury Laboratory (including our own GARNet committee member Cyril Zipfel) demonstrate that that the opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs, identifying a role for PAPS1 in the elusive connection between organ-identity and growth patterns.

 

  • Muraro D, Mellor N, Pound MP, et al. Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots. Proceedings of the National Academy of Sciences of the USA, 31 December 2013. DOI: 10.1073/pnas.1221766111.

Continuing his work on the ‘hidden half’ of plants, GARNet committee member Malcolm Bennett, with colleagues from the University of Nottingham and collaborators from Oxford, France and Finland, present this paper that looks at the factors required for root vascular patterning. Using a mathematical model, the team has been able to formulise these interactions, and has produced a minimal regulatory network capable of maintaining a stable vascular pattern in Arabidopsis roots.

 

  • Liu S, Dunwell TL, Pfeifer GP, Dunwell JM, Ullah I and Wang Y. Detection of oxidation products of 5-methyl-2’-deoxycytidine in Arabidopsis. PLOS ONE, 31 December 2013. DOI: 10.1371/journal.pone.0084620.

Recent mammalian studies have shown that the ten-eleven translocation (Tet) family of dioxygenases is involved in the oxidation of nucleobases that in turn are involved in epigenetic remodelling associated with certain human cancers. Until now, there had been little evidence to suggest that these oxidised bases are also present plants. This study, which involved Jim Dunwell from the University of Reading, and visiting colleague Ihsan Ullah from Pakistan, used a reversed-phase HPLC coupled with a tandem mass spectrometry method and stable isotope-labeled standards to identify the nucleobases in Arabidopsis genomic DNA. Very low levels were detected, which suggests that they were formed by interactions with reactive oxygen species rather than formed by any equivalent to Tet enzymes.