Effects of auxin and phenobarbital on morphogenesis and production of digitoxin in Digitalis callus

• Published in: Plant and cell physiology 1995-03, Vol.36 (2), p.247-252
• Main Authors: PALAZON, J, BONFILL, M, CUSIDO, R. M, PINOL, M. T, MORALES, C
• Format: Article
• Language: English
• Subjects: accion de los plaguicidas; action des pesticides; auxinas; auxine; auxins; Biological and medical sciences; Biotechnology; cal; callo; callus; Callus cultures; cardiovascular agents; chemical synthesis; Cytochrome P450scc; Digitalis; Digitoxin; fenobarbital; Fundamental and applied biological sciences. Psychology; Health. Pharmaceutical industry; Industrial applications and implications. Economical aspects; medicamentos cardiovasculares; modificateur cardiovasculaire; morfogenesis; morphogenese; morphogenesis; Other active biomolecules; pesticide actions; Phenobarbital; Production of active biomolecules; sintesis quimica; synthese chimique
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/oxfordjournals.pcp.a078756

Pieces of callus obtained from seedlings of Digitalis purpurea were grown on solid Murashige-Skoog's medium supplemented with 1 mg liter(-1) BA and 0.1 mg liter(-1) IAA or NAA, with or without phenobarbital (40 mg liter(-1)). The replacement of the natural auxin IAA by the synthetic auxin NAA increased callus growth and inhibited organogenesis, whereas the addition of phenobarbital had the opposite effect. Morphometric measurements revealed a high ratio of vacuole to cytoplasm (v/v) in callus cells. This ratio was affected by the different treatments in the same way as the fresh weight. The activity of mitochondrial cytochrome P450scc (the enzyme that provides the precursor, pregnenolone, for the biosynthesis of cardenolide in foxglove plants) was detected in the relevant fraction of callus grown under all experimental conditions, and its activity was increased by the addition of phenobarbital. The different treatments tested increased the cardenolide content and quantifiable amounts of digitoxin were detected in all callus tissues. It is of special interest that phenobarbital added to the culture medium increased the accumulation of digitoxin. The mechanism affecting the development and production of cardenolide in callus tissues of D. purpurea by phenobarbital and the replacement of IAA by NAA is discussed.