ISSN:
1573-5044
Keywords:
Alkaloid formation
;
ascorbate oxidase
;
auxin
;
Brugmansia candida
;
Cucumis sativus
;
gibberellic acid
;
Nicotiana rustica
;
transformed organ cultures
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Transformed organ cultures formed following transformation of plant tissues with Agrobacterium species owe their phenotypes to alterations in hormone metabolism. Exogenously supplied hormones have been used to probe the relationship between the growth and morphology of transformed root cultures of a number of species and their ability to accumulate secondary products. Auxins in the presence of low levels of kinetin induce the rapid disorganisation of transformed roots of Nicotiana rustica ultimately toform suspension cultures of transformed cells and this process is associated with a decrease in nicotine content of the cells. This is related to cells in the culture losing competence in alkaloid biosynthesis. In contrast, exogenously supplied GA3 enhanced branching in two transformed root clones of the tropane-alkaloid producing species, Brugmansia candida and so enhanced their typical “hairy root” phenotype. This growth substance had the effect of reducing the overall alkaloid accumulation but in one case significantly altered the relative concentrations of different tropine esters. In transformed roots of Cucumis sativus, the phenotype of the roots is influenced by the expression of auxin synthesis genes on TR-DNA resulting in roots with two distinct morphologies. The pattern of expression of the enzyme ascorbate oxidase in populations of control roots of different morphologies is described. The significance of these phenotypic variations on the utility of transformed root cultures for the study of secondary metabolic pathways will be discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00033871
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