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  • 1
    Electronic Resource
    Electronic Resource
    Auxin carriers in membranes of lupin hypocotyls (1986)
    Springer
    Planta 167 (1986), S. 76-80 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Auxin transport ; Lupinus ; Naphtylphthalamic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pH-driven accumulation of [3H]indolyl-3-acetic acid (IAA) has been found to occur in membrane vesicles of lupin (Lupinus albus L.) hypocotyls. Most of this association of auxin with membranes is very sensitive to osmotic shock, high concentrations of permeable weak acids, incubation at 20° C for 20 min and to some ionophores. Long incubation times also depress the ability to accumulate radioactive IAA but this ability can be partially restored by a treatment that presumably reconstitutes the pH gradient across the membranes. Two specific inhibitors of auxin transport, N-1-naphtylphthalamic acid and 2,3,5-triiodobenzoic acid, stimulate net IAA uptake with an optimum at about 10-6 M (pH 5.0). At least two auxin carriers appear to be present in the lupin membrane vesicles. An uptake carrier seems to be saturated at 10-7 M IAA in the presence of N-1-naphtylphthalamic acid, but higher IAA concentrations are needed to saturate an efflux carrier. The uptake carrier also shows a high affinity for IAA and 2,4-dichlorophenoxyacetic acid and a low affinity for 1-naphthylacetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446371
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  • 2
    Electronic Resource
    Electronic Resource
    Uptake and decarboxylation of indole-3-acetic acid during auxin-induced growth in lupin hypocotyl segments (1994)
    Springer
    Planta 193 (1994), S. 224-231 
    Details
    ISSN: 1432-2048
    Keywords: Acid-growth theory ; ATPase ; auxin (uptake, decarboxylation) ; Growth (auxin induced) ; Lupinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elongation growth of etiolated hypocotyl segments of lupin (Lupinus albus L.) was stimulated by acid pH (4.6 versus 6.5) and by IAA for periods of up to 4 h. After this time, the segments were unable to grow further. In the presence of an optimal IAA concentration (10 μM), acid pH increased the growth rate but had no effect on final growth. With suboptimal IAA (0.1 μM), however, acid pH increased growth in a more than additive way, suggesting a synergistic action between the two factors. This synergism may be explained by the increased IAA uptake and decarboxylation seen at an acid pH. These results reinforce the view that the effects of low pH and IAA on growth are not independent. Vanadate inhibited growth and also IAA uptake and decarboxylation. This inhibitor, therefore, probably inhibits growth not only by decreasing ATPase-mediated acidification but also by decreasing H+-dependent IAA uptake from the apoplasm. This dependence of IAA uptake on ATPase may be mediated by apoplasmic acidification. The amount of IAA decarboxylated increased when the assay conditions favored the growth of segments, indicating that IAA could be destroyed by decarboxylation during the auxin-induced growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192534
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of the metabolites of Indole-3-acetic acid in growing hypocotyls of Lupinus albus (1990)
    Springer
    Plant growth regulation 9 (1990), S. 315-327 
    Details
    ISSN: 1573-5087
    Keywords: IAA conjugation ; IAA decarboxylation ; HPLC ; Lupinus albus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The products of indole-3-acetic acid (IAA) metabolism by incubating hypocotyl sections and decapitated seedlings of Lupinus albus were investigated. Single treatments using [1-14C]-IAA, [2-14C]-IAA or [5-3H]-IAA and double treatments using [1-14C]-IAA+[5-3H]-IAA were carried out. Extracts from treated plant material were analyzed by paper chromatography (PC), Thin layer chromatography (TLC), and high performance liquid chromatography (HPLC). When hypocotyl sections were incubated in [2-14C]-IAA, several IAA decarboxylation products including indole-3-aldehyde (IA1), indole-3-methanol (IM), 3-hydroxymethyloxindole (HMOx), methyleneoxindole (MOx) and 3,3′-bisindolylmethane (BIM) were detected in the 95% ethanol extract; a latter extraction with 1M NaOH rendered IAA, IM and BIM, suggesting that conjugated auxins were formed in addition to conjugated IM. In sections incubated with [1-14C]-IAA, the 1M NaOH extraction also produced IAA so confirming the formation of conjugated auxins. The same decarboxylation products and two conjugated auxins, indole-3-acetylaspartic acid (IAAsp) and 1-O-(indole-3-acetyl)-β-D-glucose (IAGlu), were detected in the acetonitrile extracts from decapitated seedlings treated with [5-3H]-IAA. After a double isotope treatment ([1-14C]-IAA+[5-3H]-IAA) of decapitated seedlings, the ratio 14C/3H measured in the HPLC fractions of the acetonitrile extracts confirmed the presence of decarboxylation products as well as conjugated auxins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024917
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  • 4
    Electronic Resource
    Electronic Resource
    In vivo metabolism of labelled indole-3-acetic acid during polar transport in etiolated hypocotyls of Lupinus albus: Relationship with growth (1988)
    Springer
    Plant growth regulation 7 (1988), S. 271-288 
    Details
    ISSN: 1573-5087
    Keywords: Dual-isotope method ; hypocotyl growth ; IAA conjugation ; IAA decarboxylation ; IAA transport ; Lupinus albus ; oscillatory distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The in vivo metabolism of indole-3-acetic acid (IAA) in etiolated hypocotyls of lupin (Lupinus albus L., from Bari, Italy) was investigated by appliying IAA labelled with two radioisotopes ([1-14C]-IAA+[5-3H]-IAA) to the apical end of decapitated seedlings, followed by extraction of the radioactivity in the different regions along the hypocotyl. This method allowed detection of IAA decarboxylation in zones distant from the cut surface and, therefore, containing intact cells. When IAA was added directly in solution to the cut surface, decarboxylation was high especially in those hypocotyl regions where transient accumulations characteristic of the polar transport of IAA occurred. In 10-day-old seedlings such accumulations were observed both in the elongation zone (2nd, 3rd, and 4th cm) and in the non elongating basal zone (8th, 9th and 10th cm). When the IAA, instead, was applied with an agar block deposited on the cut surface, IAA metabolism (decarboxylation as well as conjugation) was increased but almost exclusively in tissues within 10 mm of the cut surface. In both kinds of experiment, the increase in IAA decarboxylation seemed to coincide with a decrease in the transport of IAA, since in the assay without agar the transient accumulations of radioactivity were probably due to a decrease in the transport velocity, while in the assay with agar the transport intensity was much lower than in the assay without agar. These results point to a competitive relationship between IAA metabolism and transport. Consequently, it is suggested that hypocotyl regions that probably use auxin for development processes (e.g., cell elongation and differentiation) may have a more intense IAA metabolism in parallel with their higher IAA concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037636
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