PLANT PHYSIOLOGY , Vol 108, Issue 4 1553-1560, Copyright © 1995 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Selection for Hyoscyamine and Cinnamoyl Putrescine Overproduction in Cell and Root Cultures of Hyoscyamus muticus
F. Medina-Bolivar and H. E. Flores
Graduate Program in Plant Physiology (F.M.-B.) and Department of Plant Pathology/Biotechnology Institute (H.E.F.), The Pennsylvania State University, 315 Wartik Laboratory, University Park, Pennsylvania 16802
Hairy root cultures of Hyoscyamus muticus have been shown to produce stable
levels of tropane alkaloids comparable to those found in whole plants. In
contrast, cell cultures of this and other solanaceous species produce only
trace amounts of alkaloids but can be used for selection of metabolic
variants. We have taken advantage of both systems and the ability to
convert between them in vitro in an effort to select for increased
production of the tropane alkaloid hyoscyamine. Hairy roots were converted
into cell suspensions by addition of 1 mg/L 2,4-dichlorophenoxyacetic acid
to Murashige-Skoog medium (T. Murashige and F. Skoog [1962] Physiol Plant
15: 473-497) and screened for resistance to the amino acid analog
p-fluorophenylalanine (PFP). Cells that could grow in media containing 400
[mu]M PFP were selected and cloned from single cells. The resistant cells
accumulated high levels of cinnamoyl putrescines, which share the same
biosynthetic precursors as hyoscyamine. Hairy root cultures were
regenerated from both PFP-sensitive and PFP-resistant cells by removing
2,4-dichlorophenoxyacetic acid from the medium. Resistance to PFP continued
to be expressed in regenerated roots. Higher levels of hyoscyamine were
found in hairy roots regenerated from PFP-resistant cells than were found
in controls. We suggest that the precursors overproduced by the
PFP-resistant cells can be diverted into the hyoscyamine pathway upon the
regeneration of root cultures.