Eggen T, Lillo C (2012) The antidiabetic II drug metformin in plants: uptake and translocation to edible parts of cereals, oily seeds, beans, tomato, squash, carrots and potatoes. Journal of Agricultural and Food Chemistry 60, 6929-6935
Larbat R, Olsen KM, Slimestad R, Løvdal T, Bénard C, Verheul M, Bourgaud F, Robin C, Lillo C (2012) Influence of repeated short-term nitrogen limitations on leaf phenolics metabolism in tomato. Phytochemistry 77, 119-128
Jonassen EM, Heidari B, Nemie-Feyissa D, Matre P, Lillo C (2011) Protein phosphatase 2A regulatory subunits are starting to reveal their functions in plant metabolism and development. Plant Signaling & Behavior 6, 1216-1218
Heidari B, Matre P, Nemie-Feyissa D, Meyer C, Rognli OA, Møller SG, Lillo C (2011) Protein phosphatase 2A B55 and A regulatory subunits interact with nitrate reductase and are essential for nitrate reductase activation. Plant Physiol 156, 144-164
Tang W, Yuan M, Wang R, Yang Y, Wang C, Oses-Prieto JA, Kim T-W, Zhou H-W, Deng Z, Gampala SS, Gendron JM, Jonassen EM, Lillo C, DeLong A, Burlingame AL, Sun Y, & Wang Z-Y (2011) PP2A activates brassinosteroid-responsive gene expression and plant growth by dephosphorylating BZR1. Nature Cell Biology 13, 124-131
Reumann S, Voitsekhovskaja O, Lillo C (2010) From signal transduction to autophagy of plant cell organelles: lessons from yeast and mammals and plant-specific features. Protoplasma 247, 233-256
Løvdal T, Olsen KM, Slimestad R, Verheul M, Lillo C (2010) Synergetic effects of nitrogen depletion, temperature and light on the content of phenolic compounds in leaves of tomato. Phytochemistry 71, 605-613
Olsen KM, Heh A, Jugdé H, Slimestad R, Larbat R, Bourgaud F, Lillo C (2010) Identification and characterisation of CYP75A31, a new flavonoid 3'5'-hydroxylase, isolated from Solanum lycopersicum. BMC Plant Biology 10, 21
Jolma IW, Laerum OD, Lillo C, Ruoff P (2010) Circadian oscillators in eukaryotes. WIREs System Biology and Medicine. DOI: 10.1002/wsbm.81
Jonassen E Müller, Sandsmark B AA, Lillo C (2009) Unique status of NIA2 in nitrate assimilation: NIA2 expression is promoted by HY5/HYH and inhibited by PIF4. Plant Signaling & Behavior 4, 1-3
Matre P, Meyer C, Lillo C (2009) Diversity in subcellular targeting of the PP2A B?h subfamily members. Planta 230, 935-945
Feyissa DN, Løvdal T, Olsen KM, Slimestad R, Lillo C (2009) The endogenous GL3, but not EGL3 gene is necessary for anthocyanin accumulation as induced by nitrogen depletion in Arabidopsis rosette stage leaves. Planta 230, 747- 754
Jonassen EM, Sévin DC, Lillo C (2009) The bZIP transcription factors HY5 and HYH are positive regulators of the main nitrate reductase gene in Arabidopsis leaves, NIA2, but negative regulators of the nitrate uptake gene NRT1.1. J Plant Physiol, 166, 2071-2076
Løvdal T, Lillo C (2009) Reference gene selection for quantitative real-time PCR normalization in tomato subjected to nitrogen, cold, and light stress. Analytical biochemistry, 387, 238-242
Olsen KM, Slimestad R, Lea US, Brede C, L¿vdal T, Ruoff P, Verheul M, Lillo C (2009) Temperature and nitrogen effects on regulators and products of the flavonoid pathway: Experimental and kinetic model studies. Plant Cell & Environment 32, 286-299
Lillo C (2008) Signaling cascades integrating light-enhanced nitrate metabolism. Biochem J 415: 11-9
Olsen KM, Lea US, Slimestad R, Verheul M and Lillo C (2008) Differential expression of the four Arabidopsis PAL genes: PAL1 and PAL2 have functional specialization in abiotic environmental triggered flavonoid synthesis. J Plant Physiol 165: 1491-1499
Lillo C, Lea US, Ruoff P (2008) Nutrient depletion as a key factor for manipulating gene expression and product formation in different branches of the flavonoid pathway. Plant Cell and Environment, 31, 587-601
Jonassen EM, Lea US, Lillo C (2008) HY5 and HYH are positive regulators of nitrate reductase in seedlings and rosette stage leaves. Planta 227: 559-564
Lea US, Slimestad R, Smedvig P, Lillo C (2007) Nitrogen deficiency enhances expression of specific MYB and bHLH transcription factors and accumulation of end products in the flavonoid pathway. Planta 225(5) 1245-1253
Lea US, Leydecker M-T, Quilleré I, Meyer C, Lillo C (2006) Posttranslational regulation of nitrate reductase strongly affects the levels of free amino acids and nitrat, whereas transcriptional regulation has only minor influence. Plant Physiol 140: 1085-1094
Provan F, Haavik J, Lillo C (2006) The regulatory phosphorylated serine in full-length nitrate redutase is necessary for optimal binding to a 14-3-3 protein. Plant Science, 170: 394-398
Lillo C, Jørgensen KB (2005) Summary from: Workshop on growing plants for increased nutritional value. Reports from the University of Stavanger Nr.1 Workshop report
Meyer C, Lea US, Provan F, Kaiser WM, Lillo C (2005) Is nitrate reductase a major player in the plant NO game? Photosynthesis Research 83: 181-189
Lillo C, Meyer C, Lea U, Provan F, Oltedal S, (2004) Mechanism and importance of post-translational regulation of nitrate reductase, J Exp Bot 55: 1-8
Christensen MK, Falkeid G, Loros JJ, Dunlap JC, Lillo C, Ruoff P (2004) A nitrate induced frq-less oscillator in Neurospora crassa. J Biol Rhythms 19(4): 280-286
Lea US, ten Hoopen F, Provan F, Kaiser WM, Meyer C, Lillo C (2004) Mutation of the regulatroy phosphorylation site of tobacco nitrate reductase results in high nitrite excretion and NO emission from leaf and root tissue. Planta 219: 59-65
Lillo C (2004) Light regulation of nitrate uptake, assimilation and metabolism. In :Plant Ecophysiology, Vol 3 Nitrogen Acquisition and Assimilation in Higher Plants (eds. Amancio S, and Stulen I) Chapter 6, Kluwer Academic Publisher, Dordrecht, 2004, pp149- 184
Lillo C, Lea US, Leydecker M-T, Meyer C (2003) Mutation of the regulatory phosphorylation site of tobacco nitrate reductase results in constitutive activation of the enzyme in vivo and nitrite accumulation. Plant J 35(5): 566-573.
Lillo C and Meyer C (2001) Biological Clocks and the Nitrate Reductase Oscillating System. Journal of Biological Rhythm Research. Biol Rhythm Res 32: 489-500
Lillo C, Meyer C, Ruoff P (2001) Multiple Oscillatory Feedback Loops. The Central Clock Dogma Contra Multiple Oscillatory Feedback Loops. Plant Physiol 125: 1554-1557
Appenroth K-L, Rezarta M, Jourdan V, Lillo C (2000) Phytochrome and post-translational regulation of nitrate reductase. Plant Science 159: 51-56.
Provan F, Aksland L-M, Meyer C, Lillo C (2000) Deletion of the nitrate reductase N-terminal domain still allows binding of 14-3-3 proteins but affects their inhibitoryproperties. Plant Physiol. 123: 757-764.
Lillo C, Kazaic S, Ruoff P, and Meyer C (1997) Effects of 14-3-3 proteins on NR in light and darkness. Plant Physiol. 114: 1377-1383
Lillo C, Smith LH, Nimmo HG and Wilkins MB (1996) Light/dark regulation of nitrate reductase and phosphoenol carboxylase in barley protoplasts. Planta 200: 180-185
MacKintosh C, Douglas P and Lillo C(1995) Identification of a protein that inhibits the phosphorylated form of nitrate reductase from spinach leaves. Plant Physiology 107: 451-457.
Lillo C (1994) Light regulation of nitrate reductase in green leaves of higher plants. Minireview. Phys. Plant. 90: 616-620
Lillo C and Olsen JE (1989) Growth and shoot formation in protoplast-derived calli of Brassica oleracea ssp. acephala and ssp.capitata. Plant Cell, Tissue and Organ Culture 17:91-100.
Lillo C and Shahin AS 1986 Rapid regeneration of plants from hypocotyl protoplasts and root segments of cabbage. HortScience 21(2):315-317
The main research interest of the group headed by Prof Lillo is signalling to nitrogen and flavonoid metabolism. We aim at understanding how environmental factors (light and temperature) lead to changes in gene expression and post-translational regulation of enzymes in nitrogen and flavonoid metabolism. An important aspect is how signals between different organelles and compartments of the cell integrate to control these metabolic pathways.
Regulation of nitrogen assimilation and involvement of protein phosphatases
Nitrogen is a key input factor in agriculture, often the limiting component for growth, and therefore of great economic interest. To be able to improve the efficiency of nitrogen uptake and assimilation, a solid knowledge of the cellular processes involved are necessary. To extend the current knowledge we work on regulation mechanisms on the transcriptional as well as post-transcriptional level.
Previous research results, and our current research, are in favour of protein phoshatases being important in activation of a key enzyme in nitrate assimilation, nitrate reductase, at the transcriptional as well as post-translational level (Lillo 2008). Canonical PP2A (Protein phosphatase 2A) enzymes are heterotrimeric proteins consisting of a catalytic subunit (C), a regulatory subunit (B), and a scaffolding subunit (A). In Arabidopsis thaliana there are at least 20 scaffolding/regulatory subunits, and their specific function in metabolism and physiology is hardly known. We are working on identifying the PP2A subunits interacting with nitrate reductase. When these subunits are identified we can proceed into more details concerning upstream components, and we hope to be able to understand how signals are transmitted form the chloroplasts to activate nitrate reductase in the cytosol.
Nitrate reductase can serve as a model system when investigating protein phosphatases since an easy assay is available for testing phosphorylation and dephosphorylation of this enzyme. Because basic knowledge is generally lacking concerning the physiological functions of different PP2As, the project will no doubt also lead to many interesting spin-off discoveries on the function of protein phosphatases. For reviews see Lillo et al. 2004, and Lillo 2008.
Nitrogen and temperature as key factors for regulation and product formation in the flavonoid pathway
Flavonoids are considered to important for human health as well as for the resistance of plants towards pathogens and abiotic stress. The overall long-term aim of this project is to increase the quality of fruit and vegetables by manipulating growth conditions. The project is in collaboration with Bioforsk at Særheim research station.
Flavonoids are formed in leaves in response to UV-light, nutrient depletion, and low temperature (Olsen et al. 2009). The physiological function of flavonoids in abiotic stress responses is not well understood, but flavonoids appear to be important for better tolerance of limiting nitrogen conditions. Synthesis of flavonoids are regulated by at least four classes of transcription factors in higher plants MYB, bHLH, WD40-repeat, and bZIP. To understand the influence of environmental factors at a molecular level we are testing expression profiles of regulators as well as genes encoding enzymes of the pathway.
We have been using Arabidopsis as a model plant, but are currently extending our research to tomato. For a review see Lillo et al. 2008.
Please go to this site for further information.
Olsen KM, Slimestad R, Lea US, Brede C, Løvdal T, Ruoff P, Verheul M, Lillo C (2009) Temperature and nitrogen effects on regulators and products of the flavonoid pathway: Experimental and kinetic model studies. Plant Cell & Environment 32, 286-299
Lillo C (2008) Signalling cascades integrating light-enhanced nitrate metabolism. Biochem J, 415: 11-9
Lillo C, Meyer C, Lea U, Provan F, Oltedal S (2004) Mechanism and importance of post- translational regulation of nitrate reductase. J Exp Bot: 55: 1275-1282
Dr. Michel Verheul (Bioforsk, Særheim)
Dr. Rune Slimestad (PlantChem, Særheim)
and CORE professors at UiS
Dr. Christian Meyer at INRA, Versailles, France
Prof. Fréderic Bourgaud and collaborators at the University of Nancy/INRA, France