Research Group: Plant Nutrition

• Plant-Microbe interactions and nutrient acquistion
• Nutrient transport, compartmentation and speciation
• Nutrient uptake, homeostasis and functionality
• Plant nutrition for the bio-based society

Plant uptake and transport systems of the micronutrient manganese in barley
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.

Contact: Søren Husted (shu@plen.ku.dk)

Impacts of physical root barriers and passage cells on nutrient uptake and translocation in plants
Only 40-70% of most essential macro nutrients applied to plants is removed with the harvested products. Such low values represent a major challenge to agriculture in order to reduce nutrient losses and improve the sustainability of fertilizer use. Research in this area has hitherto mainly been devoted to studies of root architecture and identification of gene and protein networks. However, roots are characterized by a remarkable physical plasticity in response to environmental impacts like drought, salt stress and nutrient availability. This plasticity is mainly reflected in passage cells and root barrier formation, which include deposition of hydrophobic lignin between adjacent endodermal cells (i.e. the Casparian strip; CS) followed by deposition of waxy lipid polyesters (suberin) between the cell wall and the plasma membrane of the individual endodermal cells. Very little is known about these root barriers and how they affect t nutrient uptake and translocation. In this project we will demonstrate that root barriers and passage cells are vital components in order to provide a complete biological model of ion uptake and translocation in crop production.

Contact: Daniel Persson (dap@plen.ku.dk)

Nanofertilization of plants
The use of nanotechnology to fertilize plants is rapidly advancing. Nanofertilization holds a range of potentials to increase the efficiency of both soil and foliar fertilization. The mobility and dissolution of fertilizers in the soil can be tailored and optimized to better match the requirements of plants and to reduce nutrient immobilization by soil minerals and microbes. Moreover, the foliar uptake and translocation of nutrients applied to the leaf surface can be improved using nanofertilizers to allow a timely and efficient restoration of nutrient functionality. However, in order to advance the development and application of nanofertilizers we still lack a better mechanistic understanding of nanoparticle uptake, translocation, dissolution and assimilation of the derived mineral ions in plant metabolism. Currently we are running three different research projects where we study these processes in cereal crops and apply the findings to synthesize nanofertilizers with an improved Mn and P use efficiency. Thus, we strive to solve an acute and significant problem in agriculture where fertilizers currently are used way to inefficient.

Contact: Søren Husted (shu@plen.ku.dk)

Sustainable production of biomass for  biorefineries
Biorefining of biomass to replace current fossil derived products is important for a transition of society to a bioeconomy and as part of the solution to mitigate climate change. An essential part of the value chain is the biomass production, and in this context choice of crop, application of nutrients and the cropping system influence the sustainability, amount and quality of the biomass. Specifically the focus is on biorefining of green biomass (grass, clover, alfalfa) which holds potential as a sustainable source of biomass in a Danish context. The intention is to extract proteins for feed/food and utilizing efficiently the pulp either to feed ruminants or upgrading it in biorefining processes to higher value products. Currently there are three ongoing projects dealing with extraction of protein where the objectives are to get better understanding of factors influencing yields in different process steps and develop novel methods based on nano-lignin materials to improve recovery of protein.

Contact: Henning Jørgensen (hej@plen.ku.dk)

Silicon – boosting the natural stress tolerance of plants
The overall aim is to quantify foliar silicon uptake and deposition from different Si sources, viz. soluble, stabilized (organically-bound) and nanoparticle-bound Si. This will be achieved by application of new technologies in ionomics and bioimaging. The relative importance of foliar entry pathways such as trichomes, stomata and cracks in anticlinal cell walls will be determined together with the pattern of Si deposition during critical growth stages. The interactions between root-absorbed Si and foliarly-applied Si will be determined, together with the interactions with other nutrients, particularly nitrogen. The molecular- physiological responses to Si provision in terms of photosynthesis, water and nutrient use-efficiency will be investigated. The project will deliver novel biological information about foliar Si absorption, its deposition, interaction with other elements and physiological impacts.

Contact: Jan K. Schjoerring (jks@plen.ku.dk)

Plant zinc sensing and regulation of zinc homeostasis
Zinc (Zn) is an essential micronutrient due to structural and catalytic roles in many proteins, and its deficiency in agricultural soils, crops and in cereal-based diets is a major global problem. Understanding the molecular basis of plant response to zinc deficiency can help improving crop zinc-use-efficiency, biofortification and adaptation to zinc deficient soils. Our team studies the regulation of the zinc homeostasis network in plants, anchored at the Arabidopsis bZIP19 and bZIP23 transcription factors, which are the central regulators of the Zn deficiency response. We address the molecular mechanisms underlying Zn sensing and signalling, and the Zn-dependent bZIP19 and bZIP23 regulatory activity and regulatory network.

Contact: Ana Assuncao (agla@plen.ku.dk)

Plant-microbe interactions to improve nutrient acquisition
Plants live closely together with bacteria and fungi that are present both in the rhizosphere around the roots and the phyllosphere on leafs, stems, grains and fruits. Some of these microbes contribute to plant health and can act as growth promoters by improving plant nutrient acquisition. Arbuscular mycorrhizal fungi significantly improve plant uptake of phosphorus and other nutrients. This symbiotic interaction is tightly controlled by the plant and we recently discovered a plant signaling peptide to be central for this regulation (Karlo et al., 2020). Nitrogen fixing bacteria may significantly contribute to plant nitrogen nutrition and thus provide a means decrease nitrogen fertilizer use and reduce the associated negative environmental impacts. However, application of nitrogen fixing bacteria in agriculture requires further exploration of natural diversity, as well as technology development to improve nitrogen fixation, aspects currently under investigation.

Mycorrhiza to improve phosphorus uptake
Our research has shown that phosphorus (P) uptake via arbuscular mycorrhiza (AM) fungi may dominate total P uptake, even in plants that do not grow better when colonized by AM fungi (Smith et al 2011). While the P transfer from fungus to plant is efficiently mediated by AM-induced Pi transporters in the peri-arbuscular membrane (Yang et al 2012), the overall P uptake by AM plants strongly depends on the abundance of root-external AM mycelium in the soil (Jakobsen et al 2016; Sawers et al 2016). We aim to enhance P uptake via the AM pathway by optimizing the proliferation of the AM mycelium into soil regions outside the root P depletion zone. This will require a solid understanding of interactions with other components of the soil microbiome as well as mechanistic insight into plant signaling pathways that control the symbiotic relationships.

Contact: Thomas de Bang (tdb@plen.ku.dk)

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