Christopher Keller

Instituce Minot State University
Adresa 500 University Ave W Minot, ND 58707, United States
+1 800-777-0750
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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).

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