Weeding the Gems

Lots of new and interesting papers from the UK Arabidopsis research community this week! New papers have been published by scientists from Rothamsted Research and the Universities of Warwick, Leicester, Aberdeen and Manchester.

• Brewer HC, Hawkins ND and Hammond-Kosack KE. Mutations in the Arabidopsis homoserine kinase gene DMR1 confer enhanced resistance toFusarium culmorum and F. graminearum. BMC Plant Biology, 29 November 2014. DOI: 10.1186/s12870-014-0317-0. [Open Access]

It was already known that mutations to the DMR1 gene affect Arabidopsis’ resistance to the biotrophic pathogens Hyaloperonospora arabidopsidis and Oidium neolycopersici. In this BMC Plant Biology paper, Nelly Brewer, Nathaniel Hawkins and Kim Hammond-Kosack from Rothamsted Research instead investigate the effects of these mutations on resistance to the ascomycete pathogens Fusarium culmorum and F. graminearum.

• Footitt S, Müller K, Kermode AR and Finch-Savage WE. Seed dormancy cycling in Arabidopsis: Chromatin remodelling and regulation of DOG1 in response to seasonal environmental signals. The Plant Journal, 1 December 2014. DOI: 10.1111/tpj.12735.

Working with collaborators in Canada, Bill Finch-Savage and Steven Footitt from the University of Warwick’s Crop Centre present the findings of a study to investigate natural variation in the expression of genes involved in chromatin remodeling in two Arabidopsis ecotypes. Several key observations were made, including changes detected in the histone modifications H3K4me3 and H3K27me3 of the DOG1 gene during dormancy cycling, leading to the proposal that these histone marks serve as a thermal sensing mechanism during dormancy cycling in preparation for light repression of dormancy.

• Hoedemaekers K, Derksen J, Hoogstrate SW, Wolters-Arts M, Oh S-A, Twell D, Mariani C and Rieu I. BURSTING POLLEN is required to organize the pollen germination plaque and pollen tube tip in Arabidopsis thaliana. New Phytologist, 1 December 2014. DOI: 10.1111/nph.13200.

David Twell from the University of Leicester was involved in this study with Dutch colleagues from Radboud University Nijmegen. The group explored the processes taking place during pollen hydration in Arabidopsis; the step in pollination before emergence of the pollen tube. Expression of the gene BURSTING POLLEN (BUP) was found to be essential for the correct organisation of a ‘germination plaque’ – an intine-like structure consisting of cellulose, callose and party de-esterified pectin – which provides passage for the emerging pollen tube.

• Chao D-Y, Chen Y, Chen J, Shi S, Chen Z, Wang C, Danku JM, Zhao F-J and Salt DE. Genome-wide association mapping identified a new arsenate reductase enzyme critical for limiting arsenic accumulation in plants. PLOS Biology, 2 December 2014. DOI: 10.1371/journal.pbio.1002009. [Open Access]

In a collaboration with scientists based in China, Fang-Jie Zhao and Yi Chen (Rothamsted Research), and new GARNet Chair David Salt (University of Aberdeen) carried out genome-wide association mapping in Arabidopsis in order to learn more about natural variation in the genetic control of the reduction of arsenate to arsenite. Understanding the control of this chemical reaction, and the extent to which inorganic arsenic accumulates in crops such as rice, is key to reducing the carcinogenic risk to human health. Analysis revealed a new arsenate reductase enzyme, High Arsenic Content 1 (HAC1).

• Dyson BC, Allwood JW, Feil R, Xu Y, Miller M, Bowsher CG, Goodacre R, Lunn JE and Johnson GN. Acclimation of metabolism to light in Arabidopsis thaliana – the glucose 6-phosphate/phosphate translocator GPT2 directs metabolic acclimation. Plant, Cell & Environment, 4 December 2014. DOI: 10.1111/pce.12495.

When transferred from low light conditions to high light conditions, mature plant leaves typically increase their photosynthetic capacity via expression of GPT2. In this study, researchers from Germany and the University of Manchester used wild type and GPT2 knockout plants to try and work out how and why this happens.

It’s all about the Institutes in today’s UK Arabidopsis Research Round-up! New work this week comes from the John Innes Centre, the Sainsbury Laboratory, Rothamsted Research – and theEuropean Bioinformatics Institute, part of the European Molecular Biology Laboratory (EMBL-EBI) based in Cambridge, makes an appearance too.

• Wirthmueller L, Roth C, Fabro G, et al. Probing formation of cargo/importin-a transport complexes in plant cells using a pathogen effector. The Plant Journal, 17 November 2014. DOI: 10.1111/tpj.12691.

With collaborators in Germany, researchers from the John Innes Centre and the Sainsbury Laboratory in Norwich deduce that complexes between the adapter proteins importin-a, and the cargo proteins they recruit for active nuclear transport, are formed dependent upon cargo specificity, variation at the importin-a nuclear localisation sequence-binding sites, and tissue-specific expression levels of importin-a.

• Hsiao A-S, Haslam RP, Michaelson LV, Liao P, Chen Q-F, Sooriyaarachchi S, Mowbray SL, Napier JA, Tanner JA and Chye M-L. Arabidopsis cytosolic acyl-CoA-binding proteins ACBP4, ACBP5 and ACBP6 have overlapping but distinct roles in seed development. Bioscience Reports, 21 November 2014. DOI: 10.1042/BSR20140139.

This Bioscience Report included a number of researchers from Rothamsted Research, and explores the previously poorly understood roles of three cytosolic acyl-CoA-bding proteins (ACBPs). Microarray data revealed that all three are expressed in seeds, but further analysis in transgenic Arabidopsis revealed overlapping, but differing physiological effects on seeds.

• Cubillos FA, Stegle O, Grondin C, Canut M, Tisné S, Gy I and Loudet O. Extensive cis-regulatory variation robust to environmental perturbation in Arabidopsis. The Plant Cell, 26 November 2014. DOI: 10.1105/tpc.114.130310.

Led by a French team, this study also involved Oliver Stegle from EMBL-EBI in Cambridge. Using drought stress as an example of environmental variation, the aim here was to produce a detailed map of the ways in which cis- and trans-acting factors affect gene expression and responses to environmental conditions in Arabidopsis thaliana.