RESUMO
The metabolism of labelled pyruvate followed by 13C NMR and the measure of glutamine synthetase (GS) showed, according to previous results, a high activity of this enzyme in suspension cells of Nicotiana plumbaginifolia. This activity could derive glutamate from the alkaloid synthesizing pathways. However, a recent work showed that the rate of the GS gene transcription was inversely proportional to the Gln/Glu ratio. The measures of Gln and Glu concentrations in Nicotiana plumbaginifolia cells revealed that high GS activity correlates with the weak value of Gln/Glu ratio. Therefore, the hypothesis of GS dysfunctioning for the non-biosynthesis of alkaloids in N. plumbaginifolia suspension cells can be discarded. This conclusion is strengthened by the results obtained when using a GS inhibitor.
Assuntos
Alcaloides/biossíntese , Datura stramonium/metabolismo , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico/biossíntese , Glutamina/biossíntese , Nicotiana/metabolismo , Proteínas de Plantas/metabolismo , Plantas Medicinais , Plantas Tóxicas , Ácido gama-Aminobutírico/biossíntese , Células Cultivadas , Datura stramonium/genética , Indução Enzimática , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica de Plantas , Glutamato-Amônia Ligase/antagonistas & inibidores , Glutamato-Amônia Ligase/genética , Espectroscopia de Ressonância Magnética , Metionina Sulfoximina/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/genética , Especificidade da Espécie , Suspensões , Nicotiana/genéticaRESUMO
PAPAVER SOMNIFERUM L. tissue cultures, issued from various explants (cotyledons, hypocotyls, roots) derived from plantlets belonging to two genotypes, were established on LS solid medium containing growth regulators (NAA, Kin) in various combinations. Hypocotyls and roots were found to be interesting explants to obtain cellular development. Many roots developed on calli growing on a medium containing NAA (1 mg/l) + Kin (0.1 mg/l) for the PS genotype while somatic proembryos redifferentiated on calli issued from PS 1639 genotype. The same growth substance combination was the most favourable for the production of morphinan alkaloids and papaverine: up to 10 x 10 (-3)% DW in roots redifferentiated from PS calluses.
RESUMO
Different matrices, obtained by varying calcium (0.1 to 1.5M) and alginate (1 to 1.5%) concentrations, were used to study the influence of immobilisation parameters on the behaviour ofS. aviculare. A significant modulation of cell growth, cell release, and scopolin production and excretion has been observed. Physiological and morphological characteristics ofSolanum aviculare cells immobilised within Ca-alginate beads were notably different from those of suspended cells. ImmobilisedS. aviculare have accumulated scopolin (up to 120 µg·g-1 FWB) within beads and excreted it into the culture medium (up to 8 µg·g-1 FWB). Contrary to suspended cells which have accumulated only traces of this metabolite within intracellular compartments (1 µg·g-1 FWB), no scopolin has been found into the culture medium.
