Ethylene (ET) controls many facets of plant growth and development under abiotic and biotic stresses. MtEIN2, as a critical element of the ET signaling pathway, is essential in biotic interactions. However, the role of MtEIN2 in responding to abiotic stress, such as combined nutrient deficiency, is less known. To assess the role of ethylene signaling in nutrient uptake, we manipulated nitrate (NO3−) and phosphate (Pi) availability for wild-type (WT) and the ethylene-insensitive (MtEIN2-defective) mutant, sickle, in Medicago truncatula. We measured leaf biomass and photosynthetic pigments in WT and sickle to identify conditions leading to different responses in both genotypes. Under combined NO3− and Pi deficiency, sickle plants had higher chlorophyll and carotenoid contents than WT plants. Under these conditions, nitrate content and gene expression levels of nitrate transporters were higher in the sickle mutant than in the WT. This led to the conclusion that MtEIN2 is associated with nitrate uptake and the content of photosynthetic pigments under combined Pi and NO3−deficiency in M. truncatula. We conclude that ethylene perception plays a critical role in regulating the nutrient status of plants.

Amino acids (AAs), important constituents of natural moisturizing factors (NMFs) of the skin are decreased in diseased conditions such as psoriasis and atopic dermatitis. No study so far investigated the uptake of AAs into isolated corneocytes (COR). The present study was performed using 19 AAs, including taurine (TAU), to measure their amount diffused into the COR and binding of these AAs to keratin. Incubation of alanine, aspartic acid, asparagine, glutamine, glutamic acid, histidine, proline, serine and TAU with the isolated COR showed uptake after 24 h of 51.6, 95.4, 98.6, 94.1, 95.6, 90.1, 94.6, 72.9 and 57.8 %, respectively, into the COR but no binding with keratin. Uptake of TAU was validated by time dependent in-vitro diffusion models 'without COR and 'with COR'. The time dependent curve fitting showed that in in-vitro diffusion model 'without COR' there was no change in the total concentration of TAU until 72 hours, while in diffusion model 'with COR' the total conc. decreased to 37.8 % after 72 hours. The Pearson's correlation coefficient 'r' between the conc. curves of both in-vitro diffusion models was -0.54 that was an evidence of significant amount of TAU uptake by the COR. AAs as part of the NMFs have a great potential to be diffused into the COR. This property of the AAs can be employed in further dermatological research on diseased or aged skin conditions with NMFs deficiency.

Hydnora abyssinica A.Br. (Hydnoraceae), a holoparasitic herb, is for the first time recorded for Abyan governorate of South Yemen. Flowers of this species were studied for their ethnobotanical, biological and chemical properties for the first time. In South Yemen, they are traditionally used as wild food and to cure stomach diseases, gastric ulcer and cancer. Phytochemical analysis of the extracts showed the presence of terpenes, tannins, phenols, and flavonoids. The volatile components of the air-dried powdered flowers were identified using a static headspace GC/MS analysis as acetic acid, ethyl acetate, sabinene, α-terpinene, (+)-D-limonene and γ-terpinene. These volatile compounds that characterize the odor and taste of the flowers were detected for the first time in a species of the family Hydnoraceae. The flowers were extracted by n-hexane, dichlormethane, ethyl acetate, ethanol, methanol and water. With exception of the water extract all extracts demonstrated activities against Gram-positive bacteria as well as remarkable radical scavenging activities in DPPH assay. Ethyl acetate, methanol and water extracts exhibited good antifungal activities. The cytotoxic activity of the extracts against FL cells, measured in neutral red assay, was only weak (IC50 > 500 μg /mL). The results justify the traditional use of the flowers of Hydnora abyssinica in South Yemen.

Under the auspices of the European Training and Networking Activity programme of the European Union, a ‘Metabolic Profiling and Data Analysis’ Plant Genomics and Bioinformatics Summer School was hosted in Potsdam, Germany between 20 and 29 September 2006. Sixteen early career researchers were invited from the European Union partner nations and the so‐called developing nations (Appendix). Lectures from invited leading European researchers provided an overview of the state of the art of these fields and seeded discussion regarding major challenges for their future advancement. Hands‐on experience was provided by an example experiment – that of defining the metabolic response of Arabidopsis to treatment of a commercial herbicide of defined mode of action. This experiment was performed throughout the duration of the course in order to teach the concepts underlying extraction and machine handling as well as to provide a rich data set with which the required computation and statistical skills could be illustrated. Here we review the state of the field by describing both key lectures given at and practical aspects taught at the summer school. In addition, we disclose results that were obtained using the four distinct technical platforms at the different participating institutes. While the effects of the chosen herbicide are well documented, this study looks at a broader number of metabolites than in previous investigations. This allowed, on the one hand, not only to characterise further effects of the herbicide than previously observed but also to detect molecules other than the herbicide that were obviously present in the commercial formulation. These data and the workshop in general are all discussed in the context of the teaching of metabolomics.

Chemical investigation of Stephania rotunda Lour. growing in Viet Nam led to the isolation and structural elucidation of three new alkaloids, 5-hydroxy-6,7-dimethoxy-3,4-dihydroisoquinolin-1(2H)-one (1), thaicanine 4-O-β-L-glucoside (6), as well as (–)-thaicanine N-oxide (4-hydroxycorynoxidine) (8), along with 23 known alkaloids. These structures were determined on the basis of MS and NMR spectroscopic data.

2,4-Dimethoxy-2-methyl-6H-pyran-3-one (1), a hitherto unknown natural product, and the calcium salt of rehmapicroside (2) have been isolated from rhizomes of the Vietnamese variety of Rehmannia glutinosa Libosch together with a series of known compounds: norcarotenoids (3–5), 2-formyl-5-hydroxymethylfurane (6), the iridoid rehmaglutin D (7), iridoid glycosides (8–12) and phenylethyl alcohol glycosides (13–17). Their structures were determined by mass and NMR spectroscopy.

In this study, we report the cloning of the three‐member LePS2 gene family of acid phosphatases via subtractive screening of a cDNA library of Pi‐starved cultivated tomato cells (Lycopersicon esculentum Mill. cv. Lukullus). As members of the plant Pi‐starvation response, LePS2 genes were tightly regulated in cultivated cells and tomato seedlings by Pi availability. The LePS2 enzymes which are most likely expressed in the cytoplasma could be involved in processes that are accompanied by degradation of phosphorylated organic substrates. Independently from exogenous phosphate supply LePS2 expression was detected in tomato endosperm during germination. LePS2 genes were differentially induced after infection with the bacterial pathogen Pseudomonas syringae and in the early stages of flower development. Using RT–PCR it was found that the gene LePS2B was the most abundant transcript in phosphate‐depleted cells, but a reduced expression was determined in floral buds and it was not found during pathogen interaction. In this respect, it is interesting that the promoter sequences of the LePS2 genes are also divergent. LePS2 gene products may have functions in developmental processes which are restricted to distinct plant tissues or cell types.

[17‐2H2]GA20‐13‐O‐[6′‐2H2]glucoside was synthesized and applied to seedlings of Phaseolus coccineus L. After incubation for 72 h the conjugate metabolites were purified and shown by LC‐ESI‐tandem‐MS and GC‐MS to be [17‐2H2]GA1‐13‐O‐[6′‐2H2]glucoside and [17‐2H2]GA29‐13‐O‐[6′‐2H2]glucoside. This is the first evidence for the conversion of intact GA‐O‐glucosides, and represents an additional metabolic pathway of the gibberellin metabolism in P. coccineus L. The results indicate that intact GA‐O‐glucosides are accepted by 2‐ and 3‐oxidases in the plant.

Phosphate (Pi) plays a central role as reactant and effector molecule in plant cell metabolism. However, Pi is the least accessible macronutrient in many ecosystems and its low availability often limits plant growth. Plants have evolved an array of molecular and morphological adaptations to cope with Pi limitation, which include dramatic changes in gene expression and root development to facilitate Pi acquisition and recycling. Although physiological responses to Pi starvation have been increasingly studied and understood, the initial molecular events that monitor and transmit information on external and internal Pi status remain to be elucidated in plants. This review summarizes molecular and developmental Pi starvation responses of higher plants and the evidence for coordinated regulation of gene expression, followed by a discussion of the potential involvement of plant hormones in Pi sensing and of molecular genetic approaches to elucidate plant signalling of low Pi availability. Complementary genetic strategies in Arabidopsis thaliana have been developed that are expected to identify components of plant signal transduction pathways involved in Pi sensing. Innovative screening methods utilize reporter gene constructs, conditional growth on organophosphates and the inhibitory properties of the Pi analogue phosphite, which hold the promise for significant advances in our understanding of the complex mechanisms by which plants regulate Pi‐starvation responses.

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