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Authors: Vallon, Ulrike
Graf, Josef A.
Kull, Ulrich
Title: Influence of calcium and calcium and calmodulin antagonists on the cytokinin-induced amaranthin accumulation in Amaranthus tricolor
Issue Date: 1989 Zeitschriftenartikel Journal of plant growth regulation 8 (1989), S. 81-92. URL
Abstract: The concentration of kinetin and kinetinriboside plays an essential role in the induction of amaranthin accumulation in cotyledons of Amaranthus tricolor during germination. The dose/effect ratio shows that kinetin induced 3- to 3.5-fold more amaranthin than kinetinriboside at the same molecular concentration. Various concentrations of exogenous Ca2+ did not influence the effects of kinetin on the betacyanin synthesis. However, when Ca2+ was applied together with kinetinriboside, the amaranthin production was stimulated. Time-course experiments show a lag phase of 16 h starting from the incubation with kinetin and a distinct increase of amaranthin thereafter. If the seedlings were treated simultaneously with kinetin and Ca2+, the increase of amaranthin started after 12 h. At 16 h of incubation in kinetin/Ca2+, the amount of amaranthin increased significantly compared to controls incubated with kinetin alone. If Ca2+ ions (16 h kinetin/Ca2+ incubation) were removed from the medium after 2 h, 4 h, and up to 14 h, the amaranthin content was enhanced compared to controls without Ca2+. The stimulating effect was highest in the presence of Ca2+ for 8 h. These data show that exogenous Ca2+ stimulated the amaranthin synthesis mainly during the first 12 h of incubation. The Ca2+ antagonists EGTA, chlorotetracycline, and CoCl2 reduced the amaranthin content up to 80%. The calmodulin antagonists chloropromazine and trifluoperazine inhibited the betacyanin accumulation up to 97% when applied at the beginning of the incubation. Neither Co2+ nor trifluoperazine after 12 h of preincubation in kinetin had inhibiting effects on the amaranthin production. Therefore, we presume that a specific period of competence is required for calmodulin-mediated Ca2+ effects on the accumulation of amaranthin induced by cytokinins in the seedlings of Amaranthus tricolor.
Appears in Collections:04 Fakultät Energie-, Verfahrens- und Biotechnik

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