Nutrient uptake, homeostasis and functionality




In this theme we study the physiological mechanisms and molecular basis underlying plant nutrient uptake, nutrient homeostasis network and its regulation, and we explore new aspects of nutrient functionality in metabolism. We currently focus on the flowing research lines:

Plant uptake and transport systems of the micronutrient manganese in barley (Hordeum vulgare)
We study the Mn uptake systems in roots and the functional role of Mn in photosystem II. We have made the observation that barley genotypes differ tremendously in their tolerance to Mn deficiency and we explore the mechanisms underlying this observation. Our objective is to provide the basis for breeding plants with a better fitness to tolerate growth in soils with a sub-optimal availability of Mn.

Silicon transport and incorporation
Plants benefit from silicon uptake which improves their growth and productivity by alleviating biotic and abiotic stresses. However, silicon may have a negative impact on the degradation of lignocellulosic biomass for bioenergy purposes. Solutions to reduce silicon either by biomass engineering or development of downstream separation methods are therefore targeted. Different cell wall components have been proposed to interact with the silica pool in plant shoots but the understanding of the underlying processes is still limited. In the present work we characterize the composition of cell walls in a low silicon mutant of Brachypodium distachyon disrupted in the Si-transporting aquaporin lsi1.  Several alterations in the composition and structure of pectin and hemicellulose fractions are revealed in the mutant plants. Enzymatic saccharification assays show that straw from mutant plants is more easily degradable during enzymatic hydrolysis. We conclude that the silicon content of plant biomass affects its enzymatic degradability and that low silicon mutants are a valuable tool to study silicon deposition and interactions with cell wall components.

Regulation of micronutrient zinc homeostasis in Arabidopsis thaliana and rice (Oryza sativa)
We study the molecular mechanisms and regulatory events of plant response to zinc supply. In zinc-deficiency conditions, plants respond by inducing gene expression of key zinc transporters and chelator producers at transcription level. Previously the basic-region leucine zipper (bZIP) transcription factors AtbZIP19 and AtbZIP23 were shown to be essential regulators of this response in A. thaliana. Now, we develop on this knowledge to further understand the molecular basis of their regulatory activity, in particular the zinc deficiency signalling mechanism. In addition, our work provides a framework for the translation of functional information between A. thaliana and crops.

Nitrogen use efficiency in interaction with elevated atmospheric carbon dioxide
Cytosolic glutamine synthetase (GS1) plays a role in both primary nitrogen assimilation and nitrogen remobilization during senescence. GS1 has been reported to be a critical determinant for yield and nitrogen use efficiency in cereal species but it is still not clear if overexpression of GS1 can consistently improve crop performance. We investigate the interactions between nitrogen supply and atmospheric CO2 level with respect to yield structure and nitrogen use efficiency of GS1 knock-out mutants of Arabidopsis and over-expressing transgenic and cisgenic lines in barley. We have observed higher grain yield and nitrogen use efficiency in barley in several independent experiments. The extra capacity for nitrogen assimilation generated via GS1 overexpression may furthermore provide a means to avoid declining grain protein levels under elevated (800 – 900 ppm) atmospheric CO2.  

The impacts of phosphorus deficiency on the photosynthetic machinery in plants
We study how phosphorus (P) deficiency affects photosynthesis and carbon fixation in plants. We have recently discovered the primary targets of P deficiency in plants and have developed procedures that allow us to measure P deficiency long before it is visually detectable.




About the research group
We work with model plant species, i.e. Arabidopsis thaliana and Brachypodium distachyon and with crop species, i.e. Hordeum vulgare and Oryza sativa.

A broad range of approaches are used including field trials, greenhouse experiments, hydroponics, molecular biology techniques, atomic spectrometry based multi-elemental analysis, genetics, bioimaging and bioinformatics.

We combine fundamental research on plant nutrition with an applied agronomic perspective, aiming to improve plant nutrient-use-efficiency, crop performance and nutritional value.

Projects/Funding: 


Publications:

  • Schmidt SB, Jensen PE, Husted S (2016) Manganese deficiency in plants: the impact on photosystem II. Trends in Plant Science, 21, 622-632.
  • Guan M, de Bang TC, Pedersen C, Schjoerring JK (2016) Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity. Plant Physiology 171, 1921-1933.
  • Guan M, Schjoerring JK (2016) Peering into the separate roles of root and shoot cytosolic glutamine synthetase 1;2 by use of grafting experiments in Arabidopsis.  Plant Signaling & Behavior (in press).
  • Pavlovic J, Samardzic J, Kostic L, Laursen KH, Natic M, Timotijevic G, Schjoerring JK, Nikolic M (2016) Silicon enhances leaf remobilization of iron in cucumber under limited iron. Annals of Botany 118, 271-280.
  • Reinhardt H, Hachez C, Bienert MD, Beebo A, Swarup K, Voss U,  Bouhidel K, Frigerio L,  Schjoerring JK, Bennett MJ, Chaumont F (2016) Tonoplast Aquaporins Facilitate Lateral Root Emergence. Plant Physiology 170, 1640-1654.
  • Azevedo H, Azinheiro SG, Munoz-Merida A, Castro PH, Huettel B, Aarts MGM, Assuncao AGL (2016) Transcriptomic profiling of Arabidopsis gene expression in response to varying micronutrient zinc supply. Genomics Data 7: 256-258.
  • Schmidt SB, Persson DP, Powikrowska M, Frydenvang J, Schjoerring JK, Jensen PE, Husted S (2015) Metal binding in photosystem II super- and subcomplexes from barley thylakoids. Plant Physiology, 168, 1490-1502.
  • Frydenvang J, van Maarschalkerweerd M, Carstensen A, Mundus S, Schmidt SB, Pedas PR, Laursen KH, Schjoerring JK, Husted S (2015) Sensitive detection of phosphorus deficiency in plants using chlorophyll a fluorescence. Plant Physiology, 169, 353-361.
  • Guan M, Møller IS, Schjoerring JK (2015) Two cytosolic glutamine synthetase isoforms play specific roles for seed germination and seed yield structure in Arabidopsis.  Journal  of Experimental Botany 66, 203-212.
  • Thomsen HC, Eriksson D, Møller IS, Schjoerring JK (2014) Cytosolic glutamine synthetase: A target for improvement of crop nitrogen use efficiency? Trends in Plant Science 19: 656-663.
  • Eriksson D, Stymne S, Schjoerring JK (2014) The slippery slope of cisgenesis. Nature Biotechnology 32, 727.
  • Assuncao AGL, Persson DP, Husted S, Schjørring JK, Alexander RD, Aarts MGM (2013) Model of how plants sense zinc deficiency.  Metallomics 5: 1110 - 1116.
  • Pavlovic J, Samardzic J, Maksimovic V, Timotijevic G, Stevic N, Laursen KH, Hansen TH, Husted S, Schjoerring JK, Liang Y, Nikolic M (2013) Silicon alleviates iron deficiency in cucumber by promoting mobilization of iron in the root apoplast. New Phytologist 198, 1096-1107.
  • Wang L, Pedas P, Eriksson D, Schjoerring JK (2013) Elevated atmospheric carbon dioxide decreases the ammonia compensation point of barley plants. Journal of Experimental Botany 64, 2713-2724.
  • Wang L, Feng Z, Schjoerring JK  (2013) Effects of elevated atmospheric CO2 on physiology and yield of wheat (Triticum aestivum L.): A meta-analytic test of current hypotheses. Agriculture, Ecosystems and Environment 178, 57-63.