Eike Libbert's research while affiliated with University of Rostock and other places
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Publications (77)
Metabolites of tryptophan were investigated using 2 systems: a bacterial (Peastem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions).
The plant system produces: indolepyruvic acid (IPyA), indoleacetaldehyde (IAAld) indoleacetic acid (IAA), indoleethanol (tryptophol, IAAol), indolecarboxyli...
Sterile plants of maize, pea, and cucumber contain less auxin (extracted with methanol or ether) than nonsterile ones. The auxin content is restored within one day by reinfecting sterile plants (or only the shoots, with roots and culture medium remaining sterile) with epiphytic bacteria strains able to produce IAA or with soaking water of nonsteril...
Dialyzed extracts from sterile and nonsterile pea seedlings perform the synthesis of tryptophan from indole-3-glycerol-1-phosphate (IGP) and L-serine. Compared with the analogous indole methabolism, there are similar dependences with regard to pH and to serine and pyridoxal-5-phosphate requirements, but the IGP conversion rate only amounts to one t...
Experiments with sterile grown maize coleoptiles were carried out to decide whether or not a biosynthetic path for β-indolyl-acetic acid (IAA) from indole exists without tryptophan occurring as an intermediate. β-Indolyl-acrylic acid as a tryptophan synthetase inhibitor significantly reduces the yield of [(3)H]tryptophan obtained from [(3)H]indole...
Previous own results demonstrated a connection between IAA production by epiphytic bacteria and the auxin level in the host plant, suggesting the following circuit of substances: plant ⟶ plant exudate (tryptophan) ⟶ epiphytic bacteria ⟶ bacterial product (auxin) ⟶ plant. Now we isolate distinct steps of this circuit from their natural environment,...
This investigation was undertaken to decide whether epiphytic bacteria increase the auxin content of their host plant only by giving off IAA, or also by supplying other metabolites, which could affect the auxin content directly or indirectly.
A nonacidic inhibitor from pea plants possessing regulatory function in apical dominance was investigated with respect to its effect on the metabolism of indole compounds in 2 experimental systems: a bacterial (pea stem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions).
Tryptophan, tryptamine, or indolepyruvic acid were applied to 2 systems: a bacterial (pea stem sections containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions).
In the plant system, the production of indoleacetic acid and indoleethanol (tryptophol) from each applied indole derivative is clearly reduced by...
The auxin content (extractable and ‘diffusible’ auxin) of non-sterile corn plants is much more increased by a tryptophan application than the auxin content of sterile plants. This effect is independent of the mode of tryptophan application (spray or supply with the transpiration stream). The epiphytic bacteria settling the shoot surface are respons...
Epiphytic, IAA-producing bacteria strains were fed with 14C-tryptophan (Try). 14C-Try absorption and, after transfer to a Try-free medium, 14C-IAA output were stated. Using 4 different methods, the 14C-Try containing bacteria were applied to the tips of sterile corn coleoptiles and the ‘diffusible’ auxin collected at the coleoptile bases by means o...
Metabolites of indolepyruvic acid and indolelactic acid were investigated using 2 systems: a bacterial (pea stem homogenates
containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). The products of spontaneous
indolepyruvic acid decomposition in aqueous solution and during chromatography were investigated,...
Metabolites of indoleacetaldehyde (IAAld), indoleethnol (tryptophol, IAAoI), tryptamine (TNH2) and indoleacetamide (IAAm) were investigated using 2 systems; a baeterial (Pea stem homogenates containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). In both systems, indoleacetic acid (IAA), IAAol and indolec...
More “diffusible” auxin is received from nonsterile than from sterile corn coleoptile tips. An artificial reinfection of sterile coleoptiles with epiphytic, IAA-producing bacteria strains does, a superinfection of nonsterile coleoptiles does not increase the auxin amount. The difference between sterile and nonsterile tips persists if diffusion from...
Indole or indoleglycerol phosphate were incubated with crude or dialyzed enzyme extracts (pH 5.4-8.0) of pea seedlings. Neither with nor without addition of serine-like cosubstrates, any formation of auxin or an auxin precursor could be detected by means of the Avena curvature test or thin-layer chromatography. In presence of indole, the auxin cont...
Under nonsterile conditions, IAA can be extracted from pea stem sections infiltrated with buffer, IAA, or tryptophan. This IAA has microbial origin, since its occurrence is prevented by antibiotics. All infiltrated IAA disappears in the sections. Under sterile conditions, several inhibitors of IAA oxidase prevent the complete disappearance of infil...
Using hydrocultured pea plants, 109 bacterial strains (42 from shoots) were isolated from shoots, roots, and from the hydroculture medium. 58 different strains (26 from shoots) were able to produce IAA from tryptophan, 15 different strains (7 from shoots) were able lo destroy IAA. (Included are 13 strains possessing both properties.) As far as they...
IAA- and gravity-induced curvatures in coleoptiles are altered by the morphactin methyl-2-chloro-9-hydroxyfluorene-(9)-carboxylate (CFM), the length of the curved part of the coleoptile being greatly reduced. A ring of CFM-containing paste blocks the bud-inhibiting effect of IAA when placed between the bud and the site of IAA application. The IAA-t...
Zusammenfassung Die als Wachstumsinhibitoren bekannten Morphaktine beeinflussen den Geotropismus nicht durch eine Wachstumsdepression: Konzentrationen, die den Geotropismus vonTriticum-Coleoptilen hemmen, fördern deren Streckungswachstum.
Homogenates of epicotyls or roots of nonsterile pea plants incubated with tryptophan produce IAA within 1 to 4 hours, which was detected by means of the Avena curvature test and thin layer chromatography.
Three results prove this short‐term IAA production to be mainly caused by epiphytic bacteria: 1) Homogenates of sterile plant parts catalyze a co...
Root initiation at the twining plant Calystegia sepium (L.) R. BR.: Stimulation by auxins,vitamins and the gibberellin antagonist 2-(chloroethyl)trimethylammonium chloride.
The morphactins — derivatives of fluorene-9-carboxylic acid —are often called antigibberellins. A competitive inhibitor of gibberellic acid (GA) should be expected to inhibit the GA-induced synthesis of -amylase, so a morphactin was tested in the barley endosperm bioassay. The morphactin did not have any effect on amylase biosynthesis, either with...
The morphactins - derivatives of fluorene-9-carboxylic acid -are often called "antigibberellins". A competitive inhibitor of gibberellic acid (GA) should be expected to inhibit the GA-induced synthesis of α-amylase, so a morphactin was tested in the barley endosperm bioassay. The morphactin did not have any effect on amylase biosynthesis, either wi...
1. Unsterile and sterile green algae (2 species tested) and red algae (3 species) were able to hydrolize indole-3-acetonitrile (IAN) to indole-3-acetic acid (IES). Indole-3-acetamide (IAAm), detected together with IES, seemed to be an intermediate. Brown algae (3 species) incubated with IAN could produce neither IES nor IAAm. All algae oxidized IAN...
1.
Unsterile and sterile green algae (2 species tested) and red algae (3 species) were able to hydrolize indole-3-acetonitrile (IAN) to indole-3-acetic acid (IES). Indole-3-acetamide (IAAm), detected together with IES, seemed to be an intermediate. Brown algae (3 species) incubated with IAN could produce neither IES nor IAAm. All algae oxidized IAN...
Plants are settled by epiphytic bacteriae able to convert tryptophan to IAA. This bacterial activity is abolished by chloramphenicol and streptomycin but not by penicillin. Tryptophan conversion to IAA by plant parts or enzyme preparations is far more intensive in non-sterile conditions than in sterile ones. This is true for all investigated object...
Root initiation at cuttings is inhibited by application of gibberellin. CCC does not antagonize this inhibition. However, CCC stimulates root initiation at cuttings of three different species of twining plants known to be rich in endogenous gibberellin. CCC seems to be an antagonist for endogenous but not for exogenous gibberellin, which suggests t...
Root initiation at cuttings is inhibited by application of gibberellin. CCC does not antagonize this inhibition. However, CCC stimulates root initiation at cuttings of three different species of twining plants known to be rich in endogenous gibberellin. CCC seems to be an antagonist for endogenous but not for exogenous gibberellin, which suggests t...
The red algae Furcellaria fastigiata, Nemalion multifidum, and the green alga Cladophora rupestris were able to hydrolyse IAN to IAA. The conversion of IAN to IAA by Furcellaria and probably by Cladophora included indoleacetamide as an intermediate.
When the brown algae Fucus vesiculosus, Pylaiella litoralis, and Halidrys siliquosa were incubated w...
Gibberellic acid (GA) when applied alone is without effect in theAvena curvature test. When applied together with indole-3-acetic acid (IES=IAA; 10–8–10–5 g/ml, GA increases the extent of the IAA-induced curvature by about 40%; this is true with all IAA concentrations including supraoptimal ones. It is computed that the stimulation by GA results fr...
Gibberellic acid (GA) was incubated in agar blocks, transported through hypocotyl sections of sunflower plants, and collected in acceptor blocks of plain agar. The amount of GA transported through the sections was tested with dwarf pea plants using a new test method in which the acceptor block was applied directly to the test plant. The GA transpor...
The effect of 2,3,5-triiodobenzoic acid (TIBA) on the translocation of various substances within etiolated pea plants was tested by applying the substances to different places on the decapitated plants and measuring the effect of the substances on the growth of lateral buds after placing a lanolin ring containing TIBA around the stem between the pl...
1.
Aus Sprossen und Wurzeln grner Erbsenpflanzen wurden mit ther Korrelationshemmstoff und seine Hemmstoffvorstufe extrahiert und auf Grund ihrer unterschiedlichen Benzollslichkeit voneinander getrennt.
2.
Die (neutrale) Fraktion, in der der Korrelations-HS enthalten ist, ergibt bei der Hydrolyse mit schwachen Suren oder Laugen saures Auxin; die Fr...
Citations
... Libbert et al. (2) have reported that adenine at 450 uM and 4500 jM enhances the movement of IAA in 5-mm segments of Heliantthus hypocotyl. Since adenine is an essential component of kinin molecules, it was considered important to determine whether adenine itself is also transported in a polar fashion. ...
... Another known fact about auxin are, it causes significant elongation of shoots, where, the internodes are properly developed. It has universal inhibitory effects on lateral bud outgrowth or under-developed/short shoots (Libbert, 1954;Snow, 1937;Thimann, 1937). Therefore, it is clearly stated that development of micropropagation protocol for largescale cultivation of plants depends upon several factors such as explant type, concentrations and kinds of growth regulators, their combinations and the culture conditions. ...
... I t had been observed that contaminated material contained more auxin than sterile one (Libbert et al., 1969). However, simultaneous infection of sterile maize seedlings with both IAA-producing and IAA-destroying bacterial strains--which m a y occur simultaneously on the surface of the maize root (Manteuffel, 1973)--did not affect the endogenous level of IAA-like compounds (Manteuffel, et al., 1972). Furthermore, conclusive identification of IAA in sterile maize roots has been published, with results quite similar to those reported here for the whole root (Elliott and Greenwood, 1974). ...
... The techniques for collection and analysis of water-soluble phylloplane carbohydrates used so far have allowed only the qualitative composition of the phylloplane to be determined, and did not give reproducible results. Soluble substances were collected either by dipping whole young plants, or by dipping isolated leaves, for a relatively long period in water (Kunert & Libbert, 1972;Morris & Rouse, 1985). The leaching of soluble substances from inner leaf tissue may result in over-estimates of substances in the phylloplane. ...
... The ability to produce the plant hormone IAA, a naturally occurring auxin, is widespread among microorganisms that are commonly associated with plant surfaces [59]. Microbes from the rhizosphere of different crops appear to have a greater potential to synthesize and release IAA as secondary metabolite because of the relatively rich supply of tryptophan [60]. ...
... This underlines the genetic and physiological differences between these phylogenetically close bacterial strains. It is worth noting that, although it has been known for decades that IAA-producing bacteria are very common in the rhizosphere [7], bacteria with the ability to both degrade and produce IAA are seemingly very rare and only occasionally reported in the scientific literature [16,[32][33][34]. Even less is known about their presence and role in the rhizosphere of aquatic plants. ...
... Such artifactua] reactions are ]ess ]ikely to occur in whole organs or whole cells; however, studies on whole cells or organs suffer from the possible infiuence of epiphytic bacteria, which are very difiicult to exc]ude comp]ete]y. Even small numbers of epiphytic bacteria can produce relatively large amounts of IAA, and this is especiaUy significant when radioactive IAA precursors are used (2). Thus studies of auxin biosynthesis, particulady those emp]oying radioactive tracers, have been clouded by uncertainty over what is artifact and what is not. ...
... During the very early stage of plant science research with auxin, the existence of bacterial IAA producers (BIPs) was recognized. On the way to measurement of IAA, the BIPs associated with plants haveconsidered as a source of contamination in plant tissues [60]. Later researches depict that BIPs cause the symptoms in many plants along with thebacterial diseases like gypsophila gall [61], knot disease in olive and oleander plants [62], russet of fruits inpear [63], and also in plant-growth-promoting rhizobacteria (PGPR) associated plants [64]. ...
... Enzymes for the conversion of tryptophan to IAA via different routes have been partially characterised (see Sembdner et al. 1981). Double labelling studies by Erdmann and Schiewer (1971) and Heerkloss and Libbert (1976) have indicated that IAA is synthesised from indole and serine via a tryptophan intermediate. Tryptophan shows auxin activity in some plant tissues e.g. ...
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... In one of the few studies on BIDs, Wichner and Libbert reported that bacteria with IAA-destroying activity could readily be isolated from plant surfaces (50). Libbert and Risch (23) described 15 such isolates from the shoots and roots of hydrocultured pea plants. ...
