Arabidopsis Research Roundup: August 21st.

There are a wide array of topics included in this weeks Arabidopsis Research Roundup, ranging from studies on stomatal density, thylakoid transport, metabolic flux analysis, mutant detection and root development. We feature unlinked studies from three researchers from the University of Oxford Plant Science (Paul Jarvis, Lee Sweetlove and Nick Harberd), whilst the papers from Julie Gray and Brian Forde share the broad theme that investigates different mechanisms that might be used to improve nitrogen uptake, either by modifying the expression of a single gene involved in root development or by altering stomatal density.

Hepworth C, Doheny-Adams T, Hunt L, Cameron DD, Gray JE (2015) Manipulating stomatal density enhances drought tolerance without deleterious effect on nutrient uptake New Phytol.

Julie Gray (University of Sheffield) is an expert on both stomatal biology and on the potential for manipulating stomatal density to improve crop production. In this study drought tolerance and soil water retention were measured in four Arabidopsis mutants with defects in epidermal patterning and stomatal density. Nutrient uptake was measured by mass flow of 15N. Plants with less stomata had reduced transpiration and were drought-tolerant yet interestingly showed little reduction in shoot N concentrations, especially when water availability is restricted. In contrast, plants with extra stomata could take up more N except when access to water was reduced. Therefore the authors show that by altering stomatal density they can generate plants that are drought resistance yet maintain nutrient uptake or generate plants with enhancing nutrient uptake is conditions with plentiful water.

Trösch R, Töpel M, Flores-Pérez Ú, Jarvis P (2015) Genetic and Physical Interaction Studies Reveal Functional Similarities between ALB3 and ALB4 in Arabidopsis. Plant Physiol.

This German, Swedish and UK collaboration is led by Paul Jarvis at the University of Oxford and broadly investigates thylakoid protein targeting. The ALB3 complex has previously been shown to target light harvesting complex proteins (LHCP) to the thylakoid. A related Arabidopsis protein, ALB4, had been proposed to interact not the LHCPs but rather with the ATP synthase complex. However this study shows that ALB3 and ALB4 have some overlapping roles in addition to their specific functions and that they can engage with a similar set of interactor proteins to bring their substrates to the thylakoid membrane.

Cheung CY, Ratcliffe RG, Sweetlove LJ (2015) A method of accounting for enzyme costs in flux balance analysis reveals alternative pathways and metabolite stores in an illuminated Arabidopsis leaf Plant Physiol.

Lee Sweetlove (Oxford University) leads this study that looks at the Flux Balance Analysis (FBA) of plant metabolism across several metabolic pathways by attaching ‘flux weighting factors’ to allow for the variable intrinsic cost of supporting each flux. This model has been applied to the Arabidopsis leaf exposed to different light regimes to explore the flexibility of the network in meeting its metabolic requirements. The authors discover interesting trade-offs between use of different carbon storage forms and in the variable consumption of ATP and NADPH by different metabolic pathways.

Belfield EJ, Brown C, Gan X, Jiang C, Baban D, Mithani A, Mott R, Ragoussis J, Harberd NP (2014) Microarray-based optimization to detect genomic deletion mutations Genom Data Dec;2:53-54

GARNet Advisory Board member Nick Harberd (Oxford University) leads this short communication that highlights the development of a tool for detection of genomic deletion mutants in Arabidopsis. Using a NimbleGen whole genome custom tiling array they successfully identify five mutants with deletion ranging from 4bp to 5kb and therefore introduce a powerful tool for analysing this type of genetic lesion in Arabidopsis and other plant species with well-constructed genomes.

Yu C, Liu Y, Zhang A, Su S, Yan A, Huang L, Ali I, Liu Y, Forde BG, Gan Y (2015) MADS-box Transcription Factor OsMADS25 Regulates Root Development through Affection of Nitrate Accumulation in Rice PLoS One

Brian Forde (Lancaster University) is the UK lead on this Chinese collaboration that focuses on nitrate accumulation and how it regulates root development in rice. This occurs via a MADS-box transcription factor OsMADS25 that, when overexpressed in Arabidopsis, promotes primary and lateral root development. Altered expression of this gene also affects root development in transgenic rice and includes significant changes in nitrate accumulation. Therefore this gene might prove to be an important target for future attempts to improve plant growth in regions with altered nitrate concentrations.

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