title: Selective desensitization of jasmonate- and pH-dependent signaling in the induction of benzophenanthridine biosynthesis in cells of Eschscholzia californica.
abstract: The biosynthesis of benzophenanthridine alkaloids, phytoalexins of Eschscholzia californica, in cultured cells can be induced by a glycoprotein preparation from yeast, methyljasmonate, artificial acidification with permeant acids, or mild osmotic stress. Each of these stimuli strongly attenuated the subsequent response to the same stimulus (homologous desensitization). Elicitor contact and artificial acidification mutually desensitized the cells for either signal. In contrast, elicitor-treated cells maintained their responsiveness to methyljasmonate or hyperosmolarity (sorbitol). Elicitor concentrations that nearly saturated the alkaloid response did not cause a detectable increase of jasmonate content. Transient acidification of the cytoplasm is a necessary step of signaling by low elicitor concentrations but was not detectable after jasmonate treatment. Seen together, the data indicate the existence of a jasmonate-dependent and jasmonate-independent (Delta pH controlled) signal pathway towards the expression of benzophenanthridine biosynthesis. Selective desensitization allows either stimulus to activate a distinct share of the biosynthetic capacity of the cell and limits the accumulation of toxic defense metabolites.
authors.affiliation: Max-Delbrück-Zentrum für Molekulare Medizin, Robert-Rössle-Str.10, D-13092 Berlin, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Färber
authors.forename: Brigitte
authors.initials: B
authors.lastname: Schumann
authors.forename: Otto
authors.initials: O
authors.lastname: Miersch
authors.forename: Werner
authors.initials: W
authors.lastname: Roos
mesh_terms: D000085:Acetates / Q000494:pharmacology*; D000470:Alkaloids / Q000096:biosynthesis*; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D003517:Cyclopentanes / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D031675:Eschscholzia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D018836:Inflammation Mediators / Q000494:pharmacology; D018613:Microscopy, Confocal / Q000379:methods; D054883:Oxylipins; D010421:Pentanoic Acids / Q000494:pharmacology; D010617:Phenanthridines / Q000737:chemistry / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013012:Sorbitol / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000085:Acetates; D000470:Alkaloids; D003517:Cyclopentanes; D018836:Inflammation Mediators; D054883:Oxylipins; D010421:Pentanoic Acids; D010617:Phenanthridines; D010937:Plant Growth Regulators; D013012:Sorbitol; C005566:pivalic acid; C072239:methyl jasmonate