Arabidopsis Research Roundup: July 11th

After a conference break the Arabidopsis Research Roundup returns with an outstanding selection of papers from UK (and mostly Scotland-based) researchers. Firstly Levi Yant provides an audio description of work that has identified important loci for adaption to harsh environments. Secondly John Doonan leads a multi-national group investigating the role of eiF4A phosphorylation within proliferating cells. Next two Scottish-based studies both investigate aspects of light signalling on different scales: a Glasgow-based consortium dissects the UVR8 signaling module while the role of phytochrome on global carbon allocation is studied by Karen Halliday’s group in Edinburgh. The final paper also involves significant Scottish involvement with Piers Hemsley at Dundee together with Simon Turner at Manchester investigating the role of s-acylation in the activity of the cellulose synthase complex.

Arnold BJ, Lahner B, DaCosta JM, Weisman CM, Hollister JD, Salt DE, Bomblies K, Yant L (2016) Borrowed alleles and convergence in serpentine adaptation. PNAS http://dx.doi.org/10.1073/pnas.1600405113 Open Access

New investigator at the John Innes Centre, Levi Yant, is the corresponding author on this study that also includes contributions from the labs of Kristen Bomblies and current GARNet Chairman David Salt. This investigation uses GWAS techniques to identify loci in Arabidopsis Arenosa that are important for growth on serpentine barrens, which are characterised by drought, mineral paucity and high levels of heavy metals. They showed that polygenic multi-trait genomic locations are important for serpentine adaptation. The authors reassessed previous independent datasets and showed that 11 loci have been identified across these studies and are therefore good candidates as drivers of convergent evolution. This study provides evidence that certain A.arenosa alleles have been introgressed from A.lyrata and that these may facilitate adaptation to a multi-hazard environment.

Levi kindly provides a short audio description of this work, that also touches on ionomics and data reuse!

Bush MS, Pierrat O, Nibau C, Mikitova V, Zheng T, Corke FM, Vlachonasios K, Mayberry LK, Browning KS, Doonan JH (2016) eIF4A RNA Helicase Associates with Cyclin-Dependent Protein Kinase A in Proliferating Cells and is Modulated by Phosphorylation Plant Physiol. http://dx.doi.org/10.1104/pp.16.00435 Open Access

eif4apic
Growth of phospho-null or phospho-mimetic mutants of eif4a1

John Doonan (Aberystwyth) is the leader of this wide collaboration of UK, US, Czech, Greek and Chinese researchers that investigate the interaction of the eIF4A RNA helicase with cyclin-dependent protein kinase A (CDKA). This interaction only occurs in proliferating cells where CDKA acts by phosphorylating specific amino acids on eIF4A. Throughout in vivo and in vitro experiments using phospho-null and phosphor-mimetic version of eIF4A, the authors show that phosphorylation acts to downregulate eIF4A activity, subsequently altering the efficacy of translation.

 

Heilmann M, Velanis CN, Cloix C, Smith BO, Christie JM, Jenkins GI (2016) Dimer/monomer status and in vivo function of salt-bridge mutants of the plant UV-B photoreceptor UVR8. Plant J http://dx.doi.org/10.1111/tpj.13260 Open Access

This exclusively University of Glasgow study is led by John Christie and Gareth Jenkins. Dimeric UVR8 is a UV photoreceptor that after UV-B interaction dissociates into monomers, which interact with COP1 to begin signal transduction. The UVR8 dimer develops through the formation of salt-bridges between individual UVR8 proteins. In this study the details of the dimerization are dissected, showing that several salt-bridge amino acids are necessary for the multiple functions of both the UVR8 dimer and monomer. Interestingly the authors show that UVR8 with conservative mutations of Asp96 and Asp107 to Asn96 and Asn107 are unable to form dimers yet retain wildtype responses to UV-B. This shows that monomeric UVR8 has the ability to normally initiate a signal transduction pathway and complicates our understanding of the in vivo role of the UVR8 dimer.

Fresh_Weight
Phy mutants have reduced biomass. Taken from: http://www.pnas.org/content/113/27/7667.abstract

Yang D, Seaton DD, Krahmer J, Halliday KJ (2016) Photoreceptor effects on plant biomass, resource allocation, and metabolic state. PNAS 113(27):7667-72 http://dx.doi.org/10.1073/pnas.1601309113

Karen Halliday (Edinburgh) is the corresponding author on this investigation into the broader impact of Arabidopsis phytochromes on carbon allocation and biomass production. Even though phytochrome mutants have reduced CO2 uptake they overaccumulate resources into sucrose and starch and show altered day:night growth rates. Overall this leads to reduced growth coincident with reduced expression of CELLULOSE SYNTHASE-LIKE genes. The authors demonstrate that phytochromes play a significant role in the control of biomass allocation and that they additionally differentially respond to external stresses. Evolutionarily this indicates that modification of phytochrome expression might be an important mechanism for responding to changing environments.

Kumar M, Wightman R, Atanassov I, Gupta A, Hurst CH, Hemsley PA, Turner S (2016) S-Acylation of the cellulose synthase complex is essential for its plasma membrane localization. Science. 353(6295):166-9 http://dx.doi.org/10.1126/science.aaf4009

Simon Turner (Manchester) and Piers Hemsley (James Hutton Institute, University of Dundee) lead this research which amalgamates the work from their individual labs and assesses the role of S-acylation on the activity of cellulose synthase complex (CSC). They show that core subunits of the CSC, cellulose synthase A (CESA) proteins, require s-acylation for their localisation to the plasma membrane, which is necessary for their in vivo activity. The authors estimate that a CSC might contain over 100 S-acyl groups, which could significantly alter its hydrophobicity and its interactions within the membrane environment.

CESpic
CES localisation: Taken from http://science.sciencemag.org/content/353/6295/166.full.pdf+html


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