Studies on the biosynthesis of tropane alkaloids by Datura stramonium L. transformed root culture. 3. The relationship between morphological integrity and alkaloid biosynthesis

• Published in: Planta Vol. 185; no. 3; pp. 385 - 390
• Main Authors: Robins, R.J, Bent, E.G, Rhodes, M.J.C
• Format: Journal Article
• Language: English
• Published: 1991
• Subjects: 2,4-D; biosynthesis; carboxy-lyases; cell differentiation; Datura stramonium; enzyme activity; kinetin; n-methylputrescine oxidase; naphthaleneacetic acid; organic decarboxylase; ornithine decarboxylase; oxidoreductases; plant morphology; putrescine n-methyltransferase; roots; tissue culture; transferases; tropane alkaloids
• ISSN: 0032-0935; 1432-2048

Transformed root cultures of Datura stramonimn, competent in tropane-alkaloid biosynthesis, have been treated with exogenous plant growth regulators. It was found that combinations of alpha-naphthalene-acetic acid, kinetin (N6-furfurylaminopurine) and 2,4-dichlorophenoxyacetic acid induced de-differentiation causing both the rooty phenotype and the hyoscyamine-biosynthetic capacity to be lost. Alkaloid biosynthesis disappeared rapidly and prior to the loss of morphological integrity. It was observed that the enzymes ornithine decarboxylase (EC 4.1.1.17), arginine decarboxylase (EC 4.1.1.19) and N-methylputrescine oxidase did not show the increase in level normally associated with subculturing the roots. The level of putrescine N-methyltransferase (EC 2.1.1.53) activity, the first enzyme fully committed to hyoscyamine biosynthesis, rapidly declined, about 80% being lost from the roots within 12 h. This activity, although showing some temporary restoration, declined further after a few days, and was totally absent from fully dispersed cultures. N-Methylputrescine oxidase persisted at a low level. Following sub-culture of established de-differentiated lines to plant-growth-regulator-free medium, limited root regeneration occurred. The roots formed showed renewed competence in alkaloid biosynthesis and putrescine N-methyltransferase and N-methylputrescine oxidase activities were restored to their normal levels. The relationship between the morphological state and alkaloid-biosynthetic capacity of the cultures is discussed in relation to the overall control of alkaloid biosynthesis.