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Wilfrid Laurier University Leaf
July 26, 2016
Canadian Excellence


Research supported by:    NRC/NSERC Operating and Discovery Grants
                                           The Research Office at Wilfrid Laurier University.
                                           The Canadian Foundation for Innovation and the
                                           Ontario Innovation Trust

Research Summary: 

Our overall focus is on elucidating mechanisms that regulate plant growth and development in the inbreeding species Linum usitatissimum (linseed or linen flax),  with particular interest in the regulation of plant height and flowering age, both of which have implications for plant breeding programs. Some time ago the emphasis was on Durrant’s environmentally induced flax “genotrophs” (Durrant, A. 1971 Heredity 27: 277-298). This earlier research centred on the peroxidase system; on the nature and role of a post-translational modification of this enzyme, on the role of isozymes induced by stress, and on the roles of the various isozymes in growth and development in general and, more specifically, in the control of plant height.
    More recently, we have been studying heritable changes in growth and development that were  induced using 5-azacytidine, a DNA demethylating agent.  When 5-azacytidine treatments were applied for short periods during germination, they induced genetically controlled changes in height and flowering age.  Four independently-induced lines that flower from 7-13 days earlier than normal are currently being investigated.  The genetic control of the induced, early-flowering phenotype is almost certainly epigenetic. In each line, the phenotype is controlled by the interaction of two or three independent loci and involves a number of concomitant changes in plant growth and development, such as reduced height and leaf number, increased internode length, decreased stem diameter, and reduced leaf size. Using genomic DNA, it has been demonstrated that the early flowering lines are hypomethylated and that, in the progeny generations of out-crosses, the hypomethylation appears to cosegregate with the early-flowering phenotype.  Furthermore, it is clear that the levels of cytosine methylation in genomic DNA differ from tissue to tissue and change systematically within tissues during development. In a continuation of this emphasis, the combined effects stress and development on cytosine methylation are being investigated.  In a new approach, we are beginning to compare the expression levels for genes involved in meristem identity and phase transition in the early flowering and their controls.

M. A. Fieldes

Full List of Journal Publications:

  • Brown, J.C.L., DeDecker M.M and Fieldes, M.A. 2008. A comparative analysis of developmental profiles for DNA methylation in 5-azacytidine-induced early-flowering flax lines and their control. Plant Science 175: 217-225.
  • Fieldes, M.A, Schaeffer S.M,, Krech M.J. and Brown J.C.L. 2005. DNA hypomethylation in 5-azacytidine-induced early-flowering lines of flax. Theor. Appl. Genet.  111: 136-149.
  • Fieldes, M.A. and Harvey C.G. 2004.  Differences in developmental programming and node number at flowering in the 5-azacytidine-induced, early-flowering flax lines and their controls.  Intl. J. Plant Sci. 165: 695-706.
  • Krech, M.J. and Fieldes,  M.A. 2003. Analysis of the developmental regulation of the cyanogenic compounds in seedlings of two lines of Linum usitatissimum L.  Can. J. Bot. 81: 1029-1038.
  • Fieldes, M.A. and Gerhardt, K.E.   2001.  Developmental and genetic regulation of ß-glucosidase (linamarase) activity in flax seedlings.  J. Plant Physiology 158: 977-989.
  • Fieldes, M.A. and Amyot, L.M.  1999.  Evaluating the potential of using 5-azacytidine as an epimutagen.  Can. J. Bot. 77: 1617-1622.
  • Gerhardt, K.E. and Fieldes, M.A. 1999.  Estimates of charge and molecular weight for fourteen guaiacol peroxidase isozymes in flax indicate that most are encoded by different genes. Electrophoresis 20: 1939-1945.
  • Fieldes, M.A. and Amyot, L.M.  1999.  Epigenetic control of early flowering in flax (Linum usitatissimum) lines induced by 5-azacytidine treatments applied to germinating seed.  J. Heredity 90: 199-206.
  • Fieldes, M.A. and Gerhardt, K.E.  1998.   Apparent differences in the posttranslational modification of peroxidase between genotrophs and genotypes and between normal and stress-induced isozymes.  Int. J. Plant Sci., 159: 504-512.
  • Fieldes, M.A. and Gerhardt, K.E.  1998.   Flax guaiacol peroxidases can be used to illustrate the possibility of misinterpreting the effects of stress on the activity of developmentally regulated enzymes.  Plant Sci. 132: 89-99.
  • Fieldes, M.A. and Gerhardt, K.E.  1994.    An examination of the ß-glucosidase (linamarase) banding pattern in flax seedling extracts using Ferguson plots and sodium dodecyl sulphate-polyacrylamide gel electrophoresis.  Electrophoresis 15: 654-661.
  • Fieldes, M.A. and Gerhardt, K.E.   1994.   Effects of Zn on flax seedlings: differences in the responses of the cationic and anionic isozymes of peroxidase.  Plant Sci. 96: 1-13.
  • Fieldes, M.A.  1994.   Heritable effects of 5-azacytidine on the growth and development of flax (Linum usitatissimum) genotrophs and genotypes.  Genome  37: 1-11.
  • Tyson, H. and Fieldes, M.A. 1992. A set of BASIC programs to evaluate relationships among protein sequences by optimum alignment and distance matrix analysis.  Comput. Methods Programs Biomed., 33: 61-72.
  • Fieldes, M.A.  1992.  Using Coomassie blue to stabilize H2O2-guaiacol stained peroxidases on polyacrylamide gels.  Electrophoresis, 13: 454-455.
  • Fieldes M.A.  1992.  An explanation of the achromatic bands produced by peroxidase isozymes in polyacrylamide electrophoresis gels stained for malate dehydrogenase.  Electrophoresis, 13: 82-86.
  • Fieldes, M.A. and Ross, J. 1991.  Peroxidase activity and relative mobility at anthesis in flax genotrophs and their F2 progeny: developmental and genetic effects.  Genome, 34: 495-504.
  • Fieldes, M.A., Gaudreault, P.-R. and Tyson H.  1989.  Heritable changes in electrophoretic properties of flax peroxidases resulting from variation of N nutrient level. Genetica, 78: 81-90.
  • Fieldes, M.A. and Dixon, B.  1988.  Malate dehydrogenase isozymes in flax genotroph leaves: differences in apparent molecular weight and charge between and within L and S.  Biochem. Genet.  26: 249-260.
  • Fieldes, M.A. and Gray, T.J.  1988.  Rm differences in leaf malate dehydrogenases of flax (Linum usitatissimum) genotrophs: apparent developmental effects.  J.  Expt. Bot.  39: 499-509.
  • Fieldes, M.A.  1988.  Relative mobility and activity of leaf malate dehydrogenase in flax (Linum usitatissimum) genotrophs and genotypes.  Biochem.  Genet. 26: 261-275.
  • Fieldes, M.A., H. Tyson and P.-R. Gaudreault.  1987.  Direct response of peroxidase isozyme relative mobility to short term environmental temperature changes in flax (Linum usitatissimum).  Plant Cell and Environment 10: 213-219.
  • Tyson. H., M.A. Fieldes and J. Starobin.  1986.  Genetic control of acid phosphatase Rm and its relationship to control of peroxidase Rm in flax (Linum) genotrophs.  Biochem. Genet. 24: 369-383.
  • Gaudreault, P.-R., H. Tyson and M.A. Fieldes.  1986.  Immunochemical characteristics of isoperoxidases from two environmentally-induced flax genotrophs (Linum usitatissimum L.). J. Exp. Bot. 37: 1180-1188.
  • Tyson, H., M.A. Fieldes, C. Cheung and J. Starobin.  1985.  Isozyme relative mobility (Rm) changes related to leaf position; apparently smooth Rm trends and some implications.  Biochem. Genet. 23: 641-654.
  • Fieldes, M.A. and H. Tyson.  1984.  Possible post-translational modification, and its genetic control, in flax genotroph isozymes.  Biochem. Genet. 22: 99-114.
  • Fieldes, M.A., J. Starobin and H. Tyson.  1984.  Visualization of both peroxidase and acid phosphatase isozymes from flax (Linum) on the same gels.  Anal. Biochem. 137: 146-150.
  • Fieldes, M.A. and H. Tyson. 1983.   Molecular weight differences in acid phosphatases of stem homogenates from L and S flax genotrophs.   Biochem. Genet. 21: 391-404.
  • Tyson, H. and M.A. Fieldes.  1982.  A BASIC program for orthogonal polynomials and retrieval of regression coefficients for original model.  Computer Programs in Biomedicine 15: 151-154.
  • Tyson, H. and M.A. Fieldes.  1982.  Molecular weight and net charge of peroxidase isozymes in F1 hybrids between L and S flax genotrophs.  Biochem. Genet. 20: 919-927.
  • Fieldes, M.A., H. Tyson and D. Marriott.  1982.  Protein profiles of flax genotrophs.  Can. J. Genet. Cytol. 24: 417-425.
  • Tyson, H. and M.A. Fieldes.  1982.  Analysis of the relationship between flower colour and degree of side branching in crosses between flax genotypes and genotrophs.  Can. J. Genet. Cytol. 24: 367-373.
  • Fieldes, M.A. and H. Tyson.  1982.  Comparative thermal stability of peroxidase isozymes from two flax genotrophs.  Can. J. Genet. Cytol. 24: 427-435.
  • Fieldes, M.A., C.L. Deal and H. Tyson.  1982.  Indoleacetic acid oxidase activity in main stem homogenates of flax genotrophs and genotypes.   Phytochem. 21: 1875-1880.
  • Tyson, H. and M.A. Fieldes.  1982.  A BASIC program package for weighted least squares solutions using a microprocessor with disc memory.  Computer Programs in Biomedicine 14: 77-84.
  • Fieldes, M.A. and H. Tyson.  1981.  Isozyme compariwsons using weighted analyses of electrophoretic mobility in a range of polyacrylamide gel concentrations.  Electrophoresis 2: 296-303.
  • Lemon, R.E., M.A. Fieldes and J. Struger.  1981.  Testing the monotony of threshold hypothesis of bird song.  Z. Tierpsychol. 56: 359-379.
  • Fieldes, M.A., C.L. Deal and H. Tyson.  1981.  Persistence of differences between peroxidase isoenzymes of flax genotrophs in tissue culture.  Phytochem. 20: 403-406.
  • Tyson, H. and M.A. Fieldes.  1980.  Differences in molecular weight between corresponding anionic peroxidase isozymes from two flax genotrophs.  Can. J. Genet. Cytol. 22: 529-534.
  • Tyson, H., S.A. Taylor and M.A. Fieldes.  1978.  Segregation of the environmentally induced relative mobility shifts in flax genotroph peroxidase isozymes.  Heredity 40: 281-290.
  • Fieldes, M.A., C.L. Deal and H. Tyson.  1977.  Preliminary characterization of peroxidase isozymes isolated from two flax genotrophs.  Can. J. Bot. 55: 1465-1473.
  • Fieldes, M.A., N. Bashour, C.L. Deal and H. Tyson.  1976.  Isolation of peroxidase from two flax genotrophs by column chromatography.  Can. J. Bot. 54: 1180-1188.
  • Fieldes, M.A., H. Tyson and N. Bashour.  1976.  Relative shifts in mobility in anionic peroxidase isoenzymes between stem base and apex of flax genotrophs.  Phytochem. 15: 247-250.
  • Bussey, H. and M.A. Fieldes.  1974.  A model for stably inherited environmentally induced changes in plants.  Nature 251: 708-710.
  • Fieldes, M.A. and H. Tyson.  1973.  Activity and relative mobility of peroxidase and esterase isozymes of flax (Linum usitatissimum) genotrophs.  I - Developing main stems.  Can. J. Genet. Cytol. 15: 731-744.
  • Fieldes, M.A. and H. Tyson.  1973.  Activity and relative mobility of peroxidase and esterase isozymes of flax (Linum usitatissimum) genotrophs.  II - F1 hybrids and nuclear DNA reversion types. Can. J. Genet. Cytol. 15: 745-755.
  • Fieldes, M.A. and H. Tyson.  1973.  Total phenolic contents and peroxidase isozymes in Linum usitatissimum.  Phytochem.  12: 2133-2143.
  • Fieldes, M.A. and H. Tyson.  1972.  Activity and relative mobility of peroxidase isozymes in genotrophs and genotypes of flax (Linum usitatissimum L.).  Can. Genet. Cytol. 14: 625-636.
  • Tyson, H. and M.A. Fieldes.  1972.  Estimates of relative amounts of peroxidase inhibitors in 2 flax (Linum usitatissimum L.) genotrophs and their reciprocal F1 hybrids.  Z. Pflanzenphysiol. 66: 385-396.
  • Hart (neé Fieldes), M.A., Tyson, H., and Bloomberg, R.  1971.  Measurement of activity of isoenzymes  in flax (Linum usitatissimum).  Can. J. Bot. 49: 2129-2137.