When inorganic phosphate is limiting, Arabidopsis has the facultative ability to metabolize exogenous nucleic acid substrates, which we utilized previously to identify insensitive phosphate starvation response mutants in a conditional genetic screen. In this study, we examined the effect of the phosphate analog, phosphite (Phi), on molecular and morphological responses to phosphate starvation. Phi significantly inhibited plant growth on phosphate-sufficient (2 mm) and nucleic acid-containing (2 mmphosphorus) media at concentrations higher than 2.5 mm. However, with respect to suppressing typical responses to phosphate limitation, Phi effects were very similar to those of phosphate. Phosphate starvation responses, which we examined and found to be almost identically affected by both anions, included changes in: (a) the root-to-shoot ratio; (b) root hair formation; (c) anthocyanin accumulation; (d) the activities of phosphate starvation-inducible nucleolytic enzymes, including ribonuclease, phosphodiesterase, and acid phosphatase; and (e) steady-state mRNA levels of phosphate starvation-inducible genes. It is important that induction of primary auxin response genes by indole-3-acetic acid in the presence of growth-inhibitory Phi concentrations suggests that Phi selectively inhibits phosphate starvation responses. Thus, the use of Phi may allow further dissection of phosphate signaling by genetic selection for constitutive phosphate starvation response mutants on media containing organophosphates as the only source of phosphorus.

In elicitor-treated potato cells, 9-lipoxygenase-derived oxylipins accumulate with the divinyl ether colneleic acid as the major metabolite. Here, the identification of a potato cDNA is described, whose predicted amino acid sequence corresponds to divinyl ether synthases, belonging to the recently identified new P450 subfamily CYP74D. The recombinant protein was expressed in Escherichia coli and shown to metabolize 9-hydroperoxy linoleic acid to colneleic acid at pH 6.5. This fatty acid derivative has been implicated in functioning as a plant antimicrobial compound. RNA blot analyses revealed accumulation of divinyl ether synthase transcripts both upon infiltration of potato leaves with Pseudomonas syringae and after infection with Phytophthora infestans.

Pflanzen und bestimmte Pilze haben im Laufe ihrer Entwicklungsgeschichte „gelernt”︁, in einer engen Assoziation im Boden, der Mykorrhiza, eine äußerst erfolgreiche Symbiose miteinander einzugehen. Arbuskuläre Mykorrhizapilze helfen Pflanzen sich auf nährstoffarmen Böden ausreichend mit Wasser, Nährsalzen und Spurenelementen zu versorgen und fördern entscheidend Diversität und Produktivität von Pflanzengesellschaften. Darüber hinaus zeigen mykorrhizierte Pflanzen eine erhöhte Widerstandsfähigkeit gegen Pathogenbefall. Im Gegenzug „bezahlt”︁ die Pflanze den Pilz für diesen Gewinn mit Kohlenhydraten in Form einfacher Zucker (Glucose, Fructose). Durch manche Erfolge in der Erforschung der Mykorrhiza auf Metaboliten‐ und Genebene beginnen wir allmählich zu erahnen, wie komplex die molekularen Interaktionen dieser Symbiose sind. Es ist zu erwarten, dass das steigende Interesse an der Mykorrhizaforschung zu neuen Einsichten in die Strategien von Pflanzen und Pilzen in der Entwicklung mutualistisch‐symbiontischer Assoziationen führen wird.

Bisher war die Funktion der Polyphenoloxidasen (PPO) unklar. Inzwischen konnte aber gezeigt werden, dass eine Tyrosinase an der Betacyan‐Biosynthese des Portulakröschens (siehe Bild) und der Roten Rübe sowie eine Chalkon‐spezifische PPO an der Auronbildung in gelben Löwenmaulblüten beteiligt ist.

Enzymes in search of a function, for polyphenol oxidases (PPOs), described as such, this situation has changed recently. A tyrosinase is involved in betacyanin biosynthesis in common portulaca (see picture) and red beet, and a chalcone‐specific PPO is responsible for the formation of aurones in yellow snapdragon flowers.

R,R-Bis­[(3-benzyl­oxazolan-4-yl)-methyl] di­sulfide, C22H28N2O2S2, is a chiral di­sulfide which is a highly effective catalyst for the enantioselective addition of diethyl­zinc to aldehydes, including aliphatic ones. The mol­ecule has crystallographic twofold rotation symmetry.

The mass spectral behavior of a series of 5-methylchromone glycosides isolated from two Aloe species was investigated by liquid chromatography/positive-ion electrospray (ES) mass spectrometry using collision-induced dissociation (CID) mass spectrometry. The CID mass spectra of the [M + H]+ ions show a typical fragmentation pattern reflecting the several substructures (substitution at C-7, C-9 and C-10, position and nature of the ester moiety at C-2) of the 5-methylchromone glycosides. Besides a series of known 5-methylchromone glycosides, nine new compounds of this type were identified by LC/ES-CIDMS from Aloe rubroviolacea and Aloe perryi (Aloeaceae).

The betalains of yellow, orange and red inflorescences of common cockscomb (Celosia argentea var. cristata) were compared and proved to be qualitatively identical to those of feathered amaranth (Celosia argentea var. plumosa). In addition to the known compounds amaranthin and betalamic acid, the structures of three yellow pigments were elucidated to be immonium conjugates of betalamic acid with dopamine, 3-methoxytyramine and (S)-tryptophan by various spectroscopic techniques and comparison to synthesized reference compounds; the latter two are new to plants. Among the betacyanins occurring in yellow inflorescences in trace amounts, the presence of 2-descarboxy-betanidin, a dopamine-derived betacyanin, has been ascertained. The detection of high dopamine concentration may be of toxicological relevance in use of yellow inflorescences as a vegetable and in traditional Chinese medicine, common uses for the red inflorescences of common cockscomb.The betaxanthins of two Celosia argentea varieties were identified as betalamic acid conjugates of dopamine (1), 3-methoxytyramine (2) and (S)-tryptophan.

The occurrence of glycolipids such as sterol glycosides, acylated sterol glycosides, cerebrosides and glycosyldiacylglycerols was examined in the three yeast species Candida albicans , Pichia pastoris and Pichia anomala , as well as in the six fungal species Sordaria macrospora , Pyrenophora teres, Ustilago maydis , Acremonium chrysogenum , Penicillium olsonii and Rhynchosporium secalis . Cerebroside was found in all organisms tested, whereas acylated sterol glycosides and glycosyldiacylglycerols were not found in any organism. Sterol glycosides were detected in P. pastoris strain GS115, U. maydis , S. macrospora and R. secalis. This glycolipid occurred in both yeast and filamentous forms of U. maydis but in neither form of C. albicans. This suggests that sterol glycoside is not correlated with the separately grown dimorphic forms of these organisms. Cerebrosides and sterol glycosides from P. pastoris and R. secalis were purified and characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. The cerebrosides are β‐glucosyl ceramides consisting of a saturated α‐hydroxy or non‐hydroxy fatty acid and a Δ4,8‐diunsaturated, C9‐methyl‐branched sphingobase. Sterol glycoside from P. pastoris was identified as ergosterol‐β‐D ‐glucopyranoside, whereas the sterol glucosides from R. secalis contain two derivatives of ergosterol. The biosynthesis of sterol glucoside in P. pastoris CBS7435 and GS115 depended on the culture conditions. The amount of sterol glucoside in cells grown in complete medium was much lower than in cells from minimal medium and a strong increase in the content of sterol glucoside was observed when cells were subjected to stress conditions such as heat shock or increased ethanol concentrations. From these data we suggest that, in addition to Saccharomyces cerevisiae , new yeast and fungal model organisms should be used to study the physiological functions of glycolipids in eukaryotic cells. This suggestion is based on the ubiquitous and frequent occurrence of cerebrosides and sterol glycosides, both of which are rarely detected in S. cerevisiae . We suggest P. pastoris and two plant pathogenic fungi to be selected for this approach.

The isolation of three C-glycosyl chromones, four anthraquinones and a mixture of phytosterols from the leaves of Aloe rubroviolacea was reported.