Data & Resources

The tissue-specific and development-dependent accumulation of secondary products in roots and mycorrhizas of larch (Larix decidua Mill.; Pinaceae) was studied using high-performance liquid chromatography and histochemical methods. The compounds identified were soluble catechin, epicatechin, quercetin 3-O-[alpha]-rhamnoside, cyanidin- and peonidin 3-O-[beta]-glucoside, 4-O-[beta]-hydroxybenzoyl-O-[beta]-glucose, 4-hydroxybenzoate 4-O-[beta]-glucoside, maltol 3-O-[beta]-glucoside, and the wall-bound 4-hydroxybenzaldehyde, vanillin, and ferulate. In addition, we partially identified a tetrahydroxystilbene monoglycoside, a quercetin glycoside, and eight oligomeric proanthocyanidins. Comparison between the compounds accumulating in the apical tissue of fine roots, long roots, and in vitro grown mycorrhizas (L. decidua-Suillus tridentinus) showed elevated levels of the major compounds catechin and epicatechin as well as the minor compound 4-hydroxybenzoate 4-O-[beta]-glucoside specifically in the root apex of young mycorrhizas. The amounts of wall-bound 4-hydroxybenzaldehyde and vanillin were increased in all of the mycorrhizal sections examined. During the early stages of mycorrhization the concentrations of these compounds increased rapidly, perhaps induced by the mycorrhizal fungus. In addition, studies of L. decidua-Boletinus cavipes mycorrhizas from a natural stand showed that the central part of the subapical cortex tissue and the endodermis both accumulate massive concentrations of catechin, epicatechin, and wall-bound ferulate compared with the outer part of the cortex, where the Hartig net is being formed.

Hordeum vulgare (barley) was grown in a defined nutritional medium with and without the arbuscular mycorrhizal fungus Glomus intraradices. HPLC of methanolic extracts from the roots of mycorrhized and non-mycorrhized plants revealed fungus-induced accumulation of some secondary metabolites. These compounds were isolated and identified by spectroscopic methods (NMR, MS) to be the hydroxycinnamic acid amides N-(E)-4-coumaroylputrescine, N-(E)-feruloylputrescine, N-(E)-4-coumaroylagmatine and N-(E)-feruloylagmatine, exhibiting a transient accumulation, and the cyclohexenone derivatives 4-(3-O-β-glucopyranosyl-butyl)-3-(hydroxymethyl)-5,5-dimethyl-2-cyclohexen-1-one and 4-{3-O-[(2′-O-β-glucuronosyl)-β-glucopyranosyl]-butyl}-3,5,5-trimethyl-2-cyclohexen-1-one (blumenin), exhibiting a continuous accumulation. A third cyclohexenone derivative, 4-{3-O-[(2′-O-β-glucuronosyl)-β-glucopyranosyl]-1-butenyl}-3,5,5-trimethyl-2-cyclohexen-1-one, was detectable only in minute amounts. It is suggested that accumulation of the amides in early developmental stages of barley mycorrhization reflects initiation of a defence response. However, the continuous accumulation of the cyclohexenone derivatives, especially blumenin, seems to correlate with the establishment of a functional barley mycorrhiza.

The effect of methyljasmonate on the induction of phenolic components in barley leaf segments was investigated. RP-HPLC of methanol extracts showed that three compounds accumulate to high concentrations in response to methyljasmonate treatment. Two of them were identified as N-(E)-4-coumaroylputrescine and N-(E)-4-coumaroylagmatine by UV-spectroscopy and mass spectrometry.

The effect of osmotically active substances on the alteration of endogenous jasmonates was studied in barley (Hordeum vulgare L. cv. Salome) leaf tissue. Leaf segments were subjected to solutions of d-sorbitol, d-mannitol, polyethylene glycol 6000, sodium chloride, or water as a control. Alterations of endogenous jasmonates were monitored qualitatively and quantitatively using immunoassays. The structures of jasmonates isolated were determined on the basis of authentic substances by capillary gas chromatography-mass spectrometry. The stereochemistry of the conjugates was confirmed by high performance liquid chromatography with diastereoisomeric references. In barley leaves, jasmonic acid and its amino acid conjugates, for example, with valine, leucine, and isoleucine, are naturally occurring jasmonates. In untreated leaf segments, only low levels of these native jasmonates were found. After treatment of the leaf tissues with sorbitol, mannitol, as well as with polyethylene glycol, an increase of both jasmonic acid and its conjugates could be observed, depending on the stress conditions used. In contrast, salt stress was without any stimulating effect on the levels of endogenous jasmonates. From barley leaf segments exposed to sorbitol (1m) for 24 h, jasmonic acid was identified as the major accumulating compound. Jasmonic acid-amino acid conjugates increased likewise upon stress treatment.

Cell Suspension cultures of Thamnosma montana were grown in Gamborg B5 medium which was best suited for acridone alkaloid formation. From the lyophilized cell material nine acridones and three acridone-monoglucosides have been isolated which were found for the first time in the genus Thamnosma. Moreover, N-methylacridone which is known from the intact plant was found. Gravacridonol monoglucoside was identified as a new alkaloid. Interestingly, most isolated alkaloids belong to the dihydrofuroacridones.

Coenzyme A thioesters of anthranilic acid and N‐methylanthranilic acid were synthesized. The corresponding N‐hydroxysuccinimidyl esters proved to be useful as activated intermediates to prepare anthraniloyl‐CoA and N‐methylanthraniloyl‐CoA. These compounds were characterized by positive and negative ion liquid secondary ion mass spectrometry. Acridone synthase from suspension cultures of Ruta graveolens catalyses the condensation of N‐methylanthraniloyl‐CoA and malonyl‐CoA. The reaction product 1,3‐dihydroxy‐N‐methylacridone was directly identified after the extraction of the assay mixture by electron impact mass spectrometry and capillary gas chromatography.

N-Methylanthraniloyl-CoA was synthesized via N-succinimidyl N-methylanthranilate and subsequent transesterification with CoA-SH . This compound was characterized by LSIMS and NMR data. An enzyme preparation from cell suspension cultures of Ruta graveolens catalyzed the formation of 1,3-dihydroxy-N-methylacridone from N-methylanthraniloyl-CoA and malonyl-CoA with a pH optimum of 7.5.