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This page is intended to provide a small sample of recent on-line papers
and abstracts to illustrate the wide range of research projects that use
duckweeds as the model system. The papers listed are not necessarily
chosen for their importance or quality, but for their range of subject
matter. Some fairly recent articles cited here are not on-line.
It is hoped that in the future more journals will choose to present their
contents or at least their abstracts on-line.
Heavy Metals
Also see this summary of salinity stress.
Amino Acid Biosynthesis and Sulfur Metabolism
Anne Datko, research bibliography (1978 - 1990)Ferreira, R.M.B. and Teixeira, A.R.N. "Sulfur starvation in Lemna leads to degradation of ribulose-bisphosphate carboxylase without plant death." J. Biol. Chem. (1992) 267: 7253-7257. [ link ] [ research bibliography of this group ]
Marianne Suter et al. (2000) "Adenosine 5'-Phosphosulfate Sulfotransferase and Adenosine 5'-Phosphosulfate Reductase Are Identical Enzymes" J. Biol. Chem. 2000 275: 930-936. [ Abstract ]
"Adenosine 5'-phosphosulfate (APS) sulfotransferase and APS reductase have been described as key enzymes of assimilatory sulfate reduction of plants catalyzing the reduction of APS to bound and free sulfite, respectively."
Inositol phosphates
C.A. Brearley and D.E. Hanke, "Metabolic evidence for the order of addition of individual phosphate esters to the myo-inositol moiety of inositol hexakisphosphate in the duckweed Spirodela polyrhiza L." Biochem. J. (1996) 314, 227–233. [ link ]
Ensley, H.E., H.A. Sharma, J.T. Barber, and M.A. Polito. 1997. Metabolism of chlorinated phenols by Lemna gibba, Duckweed. In E.L. Kruger, T.A. Anderson, and J.R. Coats (eds.), Phytoremediation of Soil and Water Contaminants, ACS Symposium Series No. 664. American Chemical Society, Washington, DC., chapter 17.Plant Growth RegulationUptake and metabolism of DDT and organophosphorus pesticides by Spirodela [ references and abstracts ]
Inhibitors
Haas, Stephanie E. and Yuri T. Yamamoto (2000) Kanamycin Sensitivity
of Transgenic and Wild Type of Duckweed. Ninth Annual NC State University
Undergraduate Research Symposium, April 27, 2000.
Kanamycin resistance genes are commonly used as a selectable marker
for plant transformation systems.
Weatherwax, S.C., Williams, S.A., Tingay, S., and Tobin, E.M. (1998) The phytochrome response of the Lemna NPR1 gene is mediated primarily through changes in abscisic acid levels. Plant Physiol. 116: 1299-1305. [ link ]CytokininsDevelopment of dormant buds (turions) is regulated by ABA (and cytokinins). [ link ]
Smart CC; Fleming AJ (1996) "Hormonal and environmental regulation of a plant PDR5-like ABC transporter." J Biol Chem 271(32):19351-7
ABC transporters are involved in the ATP-dependent efflux of a variety of structurally unrelated cytotoxic compounds. A homolog of a yeast ABC transporter was isolated from Spirodela. Transcripts of this gene accumulated following treatment with abscisic acid, and this induction was repressed by the adenine-derived hormone, kinetin.
Breaking of dormancy in turions (antagonizes abscisic acid). [ link ]GABA (gamma-aminobutyric acid)Frick H. (1991) Vitrification in vitro in Lemna minor and its maintenance by isopentenyl adenine. J Plant Physiol 137:502-504.
Isopentenyl adenine is a cytokinin commonly added to plant tissue culture media.Monesmith TT, Stomp AM, Blanchard SM. Investigation of the effect of benzyladenine on growth and protein content of L. gibba G3 (duckweed). Submitted to Physiologia Plantarum.
Kinnersley, Alan M., Auxein Corporation (kinnersleya@auxein.com) "Physiological evidence for GABA receptors in plants." Plant Physiology (1999 supplement) [ Abstract 719 ]Gibberellins
Inada, Sayaka and Shimmen, Teruo "Regulation of Elongation Growth by Gibberellin in Root Segments of Lemna minor." Plant Cell Physiol. 2000 41: 932-939.
"Exogenous GA3 did not promote the segment elongation but rather inhibited it. Uniconazole-P, a gibberellin biosynthesis inhibitor, significantly inhibited the segment elongation, and the inhibitory effect was completely nullified by GA3. In the epidermis, cell elongation was inhibited, but lateral cell expansion was not affected by uniconazole-P. ...These results suggested that endogenous gibberellin controls the elongation growth of root by regulating cell elongation. " [ abstract link ] [ also available in full-text ]
Regulation of mRNA Levels for Chloroplast Proteins
Peters, J.L. and J. Silverthorne. (1995) Organ-specific stability of two Lemna rbcS mRNAs is determined primarily in the nuclear compartment. The Plant Cell 7:131-140.Chloroplast MovementsPost-transcriptional regulation of mRNA abundance"We are interested in understanding post-transcriptional processes which influence mRNA abundance. Our studies focus on rbcSgenes which encode the small subunit of the chloroplast enzyme ribulose-1,5-bisphosphate carboxylase (SSU). This polypeptide is encoded by a nuclear gene family having identical coding regions but variable untranslated regions. The role of untranslated sequences in determining the stability of individual SSU is being studied in the duckweed Lemna gibba. This aquatic angiosperm has a reduced specialized, reduced structure comprising leaf-like fronds and green roots, both of which express rbcS genes. However, the transcription rates of individual rbcS genes do not correlate with the accumulation of the encoded mRNAs in the cytoplasm. For at least two of these transcripts (SSU and SSU5B), the half-lives of the mRNAs instead correlate with their abundance in steady-state mRNA. Further, it has been found that while these genes are transcribed at comparable rates in nuclei isolated from roots or fronds, the amount of each transcript in total steady-state RNA differs between roots and fronds. For one transcript, SSU5B which only accumulates in frond steady-state RNA, the absence of the transcript in root steady-state RNA is caused by differential turnover in root nuclei. Cytoplasmic stabilization of SSU mRNAs has also been found to occur, probably through the activity of a short-lived protein factor. The precise mechanisms underlying these processes are currently under investigation."
Tlalka M; Runquist M; Fricker M (1999) Light perception and the role of the xanthophyll cycle in blue-light-dependent chloroplast movements in Lemna trisulca L. Plant J. (England), 20(4) p447-459.Other Sites
and
Tlalka M; Fricker M (1999) The role of calcium in blue-light-dependent chloroplast movement in Lemna trisulca L. Plant J. (England), 20(4) p461-473."Chloroplast movements are a normal physiological response to changes in light intensity and provide a good model system to analyse the signal transduction pathways following light perception." "In most higher plants, chloroplasts move towards the periclinal cell walls in weak blue light (WBL) to increase light harvesting for photosynthesis, and towards the anticlinal walls as an escape reaction, thus avoiding photo-damage in strong blue light (SBL)."Malec, P., Rinaldi, R.A., Gabry_, H. Light-induced chloroplast movements in Lemna trisulca L. Identification of the motile system. Plant Sci., 120, 127–137, 1996.
and
Malec P. Kinetic modeling of chloroplast phototranslocations in Lemna trisulca L.: Two rate limiting components? J. Theoret. Biol., 169, 189–195, 1994.
The links on this page represent only a tiny fraction of the biochemical literature related to duckweeds.
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Revised: March 11, 2003