Influence of the ion-balance in the growth medium on the yield and alkaloid content ofDatura stramonium L.

Plants ofDatura stramonium var.tatula L. Torr. were grown for 24 weeks on vermiculite and provided with mineral solutions where the relative proportions of the major anions (N, S, P) and cations (K, Ca, Mg) were varied within a constant total.With all treatments a cyclic transport of alkaloids (hyoscyamine) from the roots to the upper plant parts appeared. The fluctuations in alkaloid content in the leaves followed those in the roots with a delay of 4 weeks.The interionic ratios seemed to influence growth and alkaloid content rather than to affect the ontogenic variations. In general, the response to the different treatments could be divided into two types. The nitrogen treatments which gave at the same time a higher crop yield and an increased hyoscyamine content, and the other treatments where a much lower yield and content was obtained.The scopolamine content on the other hand seemed to be more affected by the developmental stage. Also, the time of maximal yield was not influenced by the ion-balance but rather the climatic conditions.     

Effect of nitrogen and sucrose on the primary and secondary metabolism of transformed root cultures of Hyoscyamus muticus

Abatract The effect of carbon and nitrogen sources on two well-established hairy root clones, LBA1S and C58A, of Hyoscyamus muticus strain Cairo, were investigated. Both clones exhibited completely different patterns with regards to their growth rate, hyoscyamine accumulation, and fatty acid contents. Clone C58A grew faster and yielded more biomass (17.4 g l^-1, in 21 days), but produced less hyoscyamine. The maximum hyoscyamine content (120 mg l^-1) in clone LBA1S was reached in 28 days. Neither of the clones could use lactose or fructose as the sole carbon source, nor ammonium as the sole nitrogen source. The growth in the medium containing glucose was significantly reduced compared to that containing sucrose. Clone LBA1S was sensitive to the changes in sucrose concentration and an increase in ammonium in the culture medium, whereas C58A tolerated these changes better but was more sensitive to the increase in total nitrogen. Lipid synthesis was active in the exponential growth phase, and the total fatty acid content varied from 5 to 34 mg g^-1 of dry root material. The major fatty acids were linoleic, palmitic and linolenic. There were considerable differences in the total amount of lipids and in their relative ratios when different nutrients were applied.Abbreviations DW dry weight - FA fatty acids - FFA free fatty acids - FW fresh weight     

Evolutionary ecology of the tropane alkaloids of Datura stramonium L. (Solanaceae)

Abstract.— Although insect herbivory is frequently assumed to be responsible for the maintenance of plant secondary metabolites such as alkaloids, the assumption is controversial and experimental evidence for this assumption is sparse. We examined natural selection on the two major alkaloids present in the leaves of Datura stramonium and found that both alkaloids came under active selection. We found negative directional selection for scopolamine (natural selection acting to reduce scopolamine levels) and stabilizing selection for hyoscyamine (natural selection acting to maintain an intermediate level of hyoscyamine). We also present evidence that insect herbivores act as the agents of selection on these alkaloids. Finally, we show that there were no trade-offs in resistance to different species of insects.     

Alkaloid production in cultured roots of three species of Duboisia

Cultured roots were obtained from calluses of Duboisia leichhardtii, D. myoporoides and D. hopwoodii. Cultured roots of all these species produced both tropane and pyridine-type alkaloids. The selected cultured roots of D. leichhardtii showed high contents of tropane alkaloids (hyoscyamine 0.53%, scopolamine 1.16%, on a dry weight basis).     

Scopolamine and hyoscyamine production by hairy root cultures of Brugmansia candida: influence of calcium chloride, hemicellulase and theophylline

CaCl₂ (50 mM) and hemicellulase (0.5 U mg^–1) increased the intracellular accumulation (60–250%), release (60–200%) and production (45–200%) of hyoscyamine and scopolamine in hairy roots of Brugmansia candida. Theophylline (0.25 mM), alone or in combination with hemicellulase, was ineffective in increasing hyoscyamine and scopolamine production.     

Influence of chitosan,acetic acid and citric acid on growth and tropane alkaloid production in transformed roots of Brugmansia candida Effect of medium pH and growth phase

The effects of chitosan, acetic acid and citric acid on production and release of hyoscyamine and scopolamine in hairy root cultures of Brugmansia candida were studied. Chitosan and acetic acid were tested at different concentrations and also at different media pH values. At pH 5.5, and at certain concentrations, acetic acid and chitosan increased the content of root scopolamine and hyoscyamine, and promoted the release of both alkaloids. Lowering the pH to 3.5 and 4.5 reduced the accumulation of both alkaloids in the roots, but at a pH of 4.5, their release increased significantly. Acetic and citric acid stimulated the release of scopolamine and hyoscyamine. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hyoscyamine and proline accumulation in water-stressed Hyoscyamus muticus ‘hairy root’ cultures

Summary The patterns of hyoscyamine and proline accumulation were studied in Agrobacterium-transformed ‘hairy root’ cultures of Hyoscyamus muticus to determine if proline is a metabolic precursor of hyoscyamine. Root cultures were stressed osmotically with mannitol and the subsequent growth, hyoscyamine levels, and proline levels were measured after each transfer to fresh experimental medium for a total of four transfers. H. muticus ‘hairy roots’ were also treated with [U-¹⁴C] proline or [1,4-¹⁴C] putrescine and analyzed for radioactive hyoscyamine. Growth of ‘hairy root’ cultures was reduced by up to 90% in 0.4 M mannitol, and this inhibition persisted for at least four transfers. ‘Hairy root’ cultures of H. muticus accumulated hyoscyamine and free proline (up to 6-fold and 25-fold, respectively) when osmotically stressed with mannitol, and this effect also persisted for four transfers when grown in the same mannitol concentration. Because the total production of hyoscyamine was also increased by twofold, we conclude that the elevated hyoscyamine concentration results from increased hyoscyamine synthesis and not from reduced growth. H. muticus ‘hairy roots’ incorporated radioactivity from [1,4-¹⁴C] putrescine efficiently into hyoscyamine in both treatments, but failed to convert [U-¹⁴C] proline into hyoscyamine. We thus conclude that accumulated proline does not serve as a precursor for hyoscyamine.     

Effect of the nitrogen form used in the growth medium (NO3 −, NH4 +) on alkaloid production in Datura stramonium L.

Plants of Datura stramonium var. tatula L. Torr. were cultivated on vermiculite and received two different mineral solutions. In one treatment only NO₃ ^–-nitrogen was added, while in the other NO₃ ^–-nitrogen was partly (20%) replaced by NH₄ ⁺-nitrogen. Total dose of nitrogen as well as interionic ratios were kept constant in both treatments. With the combined treatment (NO₃ ^–-NH₄ ⁺) a significant higher hyoscyamine content was found at the time when highest biomass was reached. This was apparently the result of an increased alkaloid biosynthesis. Also scopolamine content was positively influenced, but only at a point past maximal biomass yield.No significant differences in amounts of nitrogen bound per plant were found between both treatments.The higher alkaloid content observed with the combined treatment was associated with a higher relative proportion of bound nitrogen present in the alkaloids. It seems that more nitrogen is available for secondary metabolism when NH₄ ⁺-nitrogen is present in the culture medium.