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  • 1
    ISSN: 1432-2048
    Keywords: Agrobacterium ; Auxin and thiophene in roots ; Root culture ; Root morphology ; Tagetes ; Thiophene ; Transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Roots of marigold (Tagetes patula L.) accumulate thiophenes, heterocyclic sulfurous compounds with strong biocidal activity. In detached roots cultured in vitro, the thiophene content was 5 μmol·(g fresh weight)-1 which is 25-times higher than in roots attached to the plant. In roots derived from tissues transformed by Agrobacterium tumefaciens and A. rhizogenes, the morphology and thiophene content varied with the bacterial strain used. Transformation stimulated the elongation of the root tips and the formation of lateral roots but lowered the thiophene level to 20–50% relative to the concentration in untransformed detached roots. A negative correlation was found between the number of laterals in a root system and the thiophene content. Extensive branching and a decrease in thiophene accumulation was evoked in untransformed roots by indole-3-acetic acid (1–10 μmol·l-1) added to the medium. Within the roots, the highest thiophene concentrations were found in the tips. The results indicate that auxin directly or indirectly plays a role in the regulation of the thiophene level in root tips.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell, tissue and organ culture 43 (1995), S. 127-130 
    ISSN: 1573-5044
    Keywords: partitioning ; root cultures ; sulphur ; Tagetes ; thiophenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Secondary metabolism is restricted to specific places in the plant. The concentrations of precursors and end products are the determining factors in the metabolic control of synthesis and breakdown of the compounds involved. Molecular control operates at the level of enzyme amount and gene expression. If the secondary product contains an element in its molecule which is derived from a mineral nutrient in the environment, the operation of the control mechanisms can be studied by varying the concentration of that mineral. This is exemplified by thiophene metabolism in root cultures ofTagetes. The characteristic groups in the molecule are two five-membered rings with a sulphur atom. In the experiments, the rate of thiophene biosynthesis was manipulated by varying the sulphate concentration in the medium. Sulphur limitation led to preferential channeling of sulphur into primary metabolism and a concomitant drop in thiophene biosynthesis. The major part of the reduction was caused by a drop in enzyme activity. Substrate availability played a minor role. The results indicate that sulphur is involved in the molecular control of secondary metabolism inTagetes.
    Type of Medium: Electronic Resource
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