Dr. Chris Keller

Christopher Keller, Ph.D.
Professor of Biology

Office: 219 Moore
Phone: (701) 858-3067
E-mail: christopher.keller@minotstateu.edu

Dr. Chris Keller
Dr. Keller deep in thought.

Research Students

2004-2005 research students with Dr. Keller include (left to right) Shanna Mazurek, Josh Seil, and Morgan Grundstad.

Education
Dr. Keller earned both a B. S. and M. S. from the Department of Botany at the University of British Columbia. He completed his doctorate at the University of Washington in 1994 where he subsequently worked as a postdoctoral research associate until joining the Biology Faculty at Minot State University in 1997

Courses offered

BIOL 111 (Concepts of Biology)
BIOL 150 (General Biology I)
BIOL 346 (Developmental Biology)
BIOL 349 (Plant Physiology)
BIOL 360 (Plant Morphology)
BIOL 458 (Anatomy of Seed Plants)

bean plant photo

Auxin-induced leaf growth inhibition after six days. Application of an auxin transport inhibitor (in lanolin) to the leaf petiole traps leaf auxin within the leaf and selectively increases leaf auxin content. After six days the treated leaf is much smaller than the opposite control leaf. See Keller et al., 2004 for details

Research Interests
Dr. Keller's principle research interests concern mechanisms of growth and development control in plants. In particular he is interested in how the auxins (a class of morphogenic hormones) effects various aspects of plant growth.

His dissertation project, examined the trans-membrane ion flux effects of auxins on oat coleoptile cortex cells. Auxin was found to activate both K+ uptake (Keller CP and Van Volkenburgh E, 1996a; pdf) as well as a transient Cl- efflux (Keller and Van Volkenburgh, 1996b; pdf). In a post-doctoral project he discovered that tobacco excised leaf tissues are auxin sensitive (Keller CP and Van Volkenburgh E, 1997; pdf) but grow in response to the hormone by a mechanism that differs from that found in stem and coleoptile tissues (Keller CP and Van Volkenburgh E, 1998, pdf)

Work in his lab has primarily focused on the role of auxin in controlling leaf expansion in the common bean (Phaseolus vulgaris) and in Arabidopsis . Increases in leaf auxin in intact plants was found to inhibit leaf expansion by a mechanism not involving induction of ethylene (another plant hormone well known to be increased by auxin) (Keller et al., 2004; pdf). In vitro, however, auxin has been found to have the opposite effect. Excised leaf strips respond to auxin with increased growth (Keller, 2004). Possible explanations for the opposite effects of auxin in intact and isolated leaf tissues are being investigated.

Dr. Keller is also involved in a collaborative project with Dr. Barkosky to investigate the primary mechanism of allelopathic growth inhibition. Allelochemicals are compounds released by some plants into the soil environment resulting in reduced growth by other plants. The target species typically exhibits reduced photosynthesis and growth probably as a result of perturbations occurring at the level of the root cell membrane. Results to date show that the known allelochemical hydroquinone results in a sustained depolarization of bean root cell membrane potentials at concentrations at least as low as 10 µM. Root membrane depolarization correlates with depressed plant growth as variously measured (Mazurek et al., 2004).

Publications

Keller CP (2007) Leaf expansion in Phaseolus: transient auxin-induced growth increase. Physiol. Plant. 130: 580-589 (pdf)

Keller CP, Stahlberg R, Barkawi L, and Cohen JD (2004) Long-term inhibition by auxin of leaf blade expansion in bean (Phaseolus vulgaris) and Arabidopsis thaliana. Plant Physiology 134: 1217-1226 (pdf)

Keller CP and Van Volkenburgh E (1998). Evidence that auxin-induced growth of tobacco leaf tissues does not involve cell wall acidification. Plant Physiology 118: 557-564 (pdf)

    Keller CP and Van Volkenburgh E (1997). Auxin-induced epinasty of tobacco leaf tissues. A non-ethylene mediated response. Plant Physiology 113: 604-610 (pdf)

      Keller CP and Van Volkenburgh E (1996a). Osmoregulation by Avena sativa L. coleoptile protoplasts. Effect of auxin. Plant Physiology 110: 1007-1016 (pdf)

        Keller CP and Van Volkenburgh E (1996b). The electrical response of Avena coleoptile cortex to auxins. Evidence in vivo for activation of a Cl- conductance. Planta 198: 404-412 (pdf)

          Elzenga JTM, Keller CP and VanVolkenburgh E (1991) Patch clamping protoplasts from vascular plants. Method for the quick isolation of protoplasts having a high success rate of gigaseal formation. Plant Physiology 97: 1573-1575 (pdf)

            Keller CP and Taylor IEP (1989) Acid extension in vitro of epidermal tissues from Phaseolus vulgaris hypocotyls. Canadian Journal of Botany 67: 2944-2952 (pdf)

              Presentations at national and international meetings since 2000

              Keller CP (2004) Leaf attachment required for auxin induced growth inhibition of Phaseolus leaves Auxin 2004 May 22-27, 2004 Kolympari, Crete, Greece (abstract accepted; pdf)

                Keller CP (2001) Auxin control of leaf expansion in the common bean (Phaseolus vulgaris). Plant Biology 2001. The quadrennial joint annual meetings of the American Society of Plant Physiologists and the Canadian Society of Plant Physiologists, July 21-25, 2001. Providence, RI, USA http://abstracts.aspb.org/aspp2001/public/P31/0042.html

                  Presentations at regional meetings
                  * indicates MSU undergraduate researcher/presenter

                  Keller CP (2004) Leaf intactness is required for auxin-induced growth inhibition of Phaseolus vulgaris (common bean) leaf mesophyll. Proceedings of the 96th Annual Meeting of the North Dakota Academy of Science Vol. 58, p. 15

                    *Mazurek SA, Barkosky RR, Keller CP (2004) The effect of hydroquinone on root membrane potentials and growth of the common bean (Phaseolus vulgaris). Proceedings of the 95th Annual Meeting of the North Dakota Academy of Science Vol. 58, p. 41(pdf)

                      Keller CP (2003) Effect of petiole treatment with the auxin transport inhibitor N-1-Naphthylphthalamic acid on leaf blade auxin concentration in the common bean (Phaseolus vulgaris). Proceedings of the 95th Annual Meeting of the North Dakota Academy of Science Vol. 57, p. 13

                        *Brethheim S, Barkosky RR and Keller CP (2003) Chlorophyll content of common bean (Phaseolus vulgaris) treated with N-1-Naphthylphthalamic acid (NPA). Proceedings of the 95th Annual Meeting of the North Dakota Academy of Science Vol. 57, p. 20

                          *Strand COM, Barkosky RR, and Keller CP (2003) Effect of auxin transport inhibitor N-1-Naphthylphthalamic acid on photosynthesis, stomatal conductance, and internal CO2 concentration in the common bean (Phaseolus vulgaris). Proceedings of the 95th Annual Meeting of the North Dakota Academy of Science Vol. 57, p. 19

                            *Suchy L, Keller CP, and Barkosky RR (2003) Hydroquinone-induced root membrane hyperpolarization in Phaseolus vulgaris: possible mechanisms of allelopathic interference. Proceedings of the 95th Annual Meeting of the North Dakota Academy of Science Vol. 57, p. 25

                              Keller CP (2002) Effect of exogenous auxin on leaf expansion in the common bean (Phaseolus vulgaris). Proceedings of the 94th Annual Meeting of the North Dakota Academy of Science Vol. 56, p. 63

                                *Tranby TL and Keller CP (2002) Auxin-induced leaf growth inhibition in Phaseolus vulgaris (the common bean). Proceedings of the 94th Annual Meeting of the North Dakota Academy of Science Vol. 56, p. 40

                                  Keller CP (2001) Hormonal control of leaf expansion in the common bean (Phaseolus vulgaris). Proceedings of the 93rd Annual Meeting of the North Dakota Academy of Science. Vol. 55, p. 60

                                    *Tranby TL and Keller CP (2001) Effect of auxin transport inhibitors on leaf expansion in the common bean (Phaseolus vulgaris). Proceedings of the 93rd Annual Meeting of the North Dakota Academy of Science. Vol. 55, p. 35

                                      *Tranby TL and Keller CP (2000) Auxin-induced cell wall loosening and the control of tobacco leaf cell expansion. Proceedings of the 92nd Annual Meeting of the North Dakota Academy of Science, 54, p. 16.

                                        *Brodeur DM and Keller CP (2000) The role of apically produced auxin in leaf development in bean (Phaseolus vulgaris) plants. Proceedings of the 92nd Annual Meeting of the North Dakota Academy of Science, 54, p. 33.

                                          Barkosky RR and Keller CP (2000) The effect of caffeic acid in root cell membrane potentials in leafy spurge (Euphorbia esula L.). Proceedings of the 92nd Annual Meeting of the North Dakota Academy of Science, 54, p. 31.