Enrichment of pharmaceutically important vinca alkaloids, vinblastine and vincristine, in the leaves of Madagascar periwinkle (Catharanthus roseus) plants through different pre- or postharvest treatments or cultivation conditions, e.g., exposing the plants to UV-irradiation, has been in focus for decades. Controlled LED environment in the visible light range offers the possibility of monitoring the changes in the concentration of metabolites in the vinca alkaloid-related pathway without involving UV-related abiotic stress. In the frame of our targeted metabolomics approach, 64 vinca alkaloids and metabolites were screened with the help of a UPLC-ESI-QTOF-MS instrumental setup from the leaf extracts of C. roseus plants grown in chambers under control (medium light), low light, and high blue / high red/ high far-red conditions. Out of the 14 metabolites that could be assigned either unambiguously with authentic standards or tentatively with high resolution mass spectrometry-based methods, all three dimer vinca alkaloids, that is, 3',4'-anhydrovinblastine, vinblastine and vincristine showed an at least nine-fold enrichment under high blue irradiation when compared with the control conditions: final concentrations of 961 mg kg^-1 dry weight, 33.8 mg kg^-1 dry weight, and 11.7 mg kg^-1 dry weight could be achieved, respectively. As supported by multivariate statistical analysis, the key metabolites of the vinca alkaloid pathway were highly represented among the metabolites that were specifically stimulated by high blue light application.

Information about genotype- or light-dependent differences in the dynamics of polyamine uptake and metabolism is limited in plants. In the present study, these differences were characterised in putrescine-treated three wheat genotypes grown on hydroponic solution in growth chamber. Putrescine treatment induced putrescine accumulation especially in the roots; however, distinct variations indicated different regulation strategies among the genotypes. In Mv Béres, decreased expression of polyamine synthesis and back-conversion-related genes was detected, which partly mitigated excessive putrescine build-up, reaching a 976% increase maximum after 13 h, compared to the 0-h-control. In Mv Emese, the putrescine synthesis and absorption decreased, the synthesis and back-conversion of higher polyamines were not, but the terminal catabolism was initiated, and after 5 h and 642% maximum increase resulted in successful catabolism of putrescine excess. In TC33 a lower, but persistent putrescine accumulation was found with 412, 359, 418 and 419% increases after 1, 3, 5 and 7 h, respectively. However, the illumination had less influence on the root polyamine-pools than the exogenous polyamine treatments. The effects of putrescine or spermidine treatments on polyamine homeostasis were also monitored under continuous light or dark in Mv Emese. In contrast to the roots, at least in a 24-h period, the circadian rhythm had a primary influence, rather than polyamine treatments or the absence of light in the leaves. Understanding how the genotype and light influence polyamine metabolism contributes to selecting genotypes with favourable polyamine regulatory mechanisms and optimising crop management strategies, leading to improved crop productivity.

Light spectrum may also affect the stress acclimation processes in plants. The main aim of the present study was to reveal how the additional blue light may affect the stress-related processes in winter wheat (Triticum aestivum L. cv. Mv Béres) under control and cold hardening conditions. Plants were grown under either white or blue light conditions, then cold treatment was carried out either in the same light, or plants were transferred from white to blue or from blue to white light conditions. The chlorophyll-a fluorescence induction data suggested that the used cold acclimation did not cause severe stress; and together with the metabolomics data, they suggest that the temperature acclimation processes are influenced by the spectrum during both the growth and cold acclimating periods. Twelve out of the 77 compounds identified in untargeted metabolite analysis have been described here for the first time, to the best of our knowledge. Quinic acid derivatives substantially increased at low temperature, especially those that were grown under blue light. While most of the agmatine derivatives decreased, the putrescine derivatives increased at low temperatures both in the leaves and roots; however, the effect of spectrum was less obvious. Blue light influences cold-induced gene expression, especially in the ICE-CBF-COR pathway, which is essential for freezing tolerance in plants, physiological adaptations, and stress responses at metabolite levels. In conclusion, present results demonstrate that blue light may induce specific cold acclimation processes in wheat leaves, and certain effects of light signals can also be detected in the roots.

Background The increasing number of patients treated with biologic therapies, the extending duration and costs of these treatments necessitate the development of strategies to the tapering or discontinuation of biologics in rheumatoid arthritis (RA) patients with long-standing remission on these agents. As flares occur frequently in patients in whom biologics are stopped, the identification of predictive markers for the preservation of long-standing remission after discontinuation is an important need. Several microRNA-s (miRNA) and SuPar (soluble urokinase plasminogen activator receptor) have been found to correlate with disease activity, and to be sensitive biomarkers of treatment response. Objectives The authors' aim was to prospectively follow the disease course after the permanent cessation of biologics, and to identify clinical and biochemical predictors of sustained biologic-free remission. Methods In this prospective, multicentre, controlled trial, eligible RA patients were treated with anti-TNF or IL6R-blocker, had a minimum of one-year remission (DAS-28<2.6), and no corticosteroid therapy. After discontinuation of the biologics, DAS28, HAQ, ESR and CRP were recorded at baseline, month 1, 3 and every 3 months thereafter. SuPar and soluble miRNA146a, miRNA16, miRNA155, miRNA223 and miRNA346 levels were measured by ELISA or QRT-PCR, respectively at baseline, month 1, 3, 6 and at relapse, if occurred. In the control group (n=5), patients had sustained remission on biologics, and had similar demographic and serological parameters, but the biologic therapy was not stopped. Results At present 23 patients with RA have been enrolled (average age: 59,95/35–79/ years).The mean duration of biologic therapy was 54,04 (25–84) months, and was started an average of 62,3 months (1–240 months) after the diagnosis. After the discontinuation, 14 patients are in biologic-free remission for an average of 5,21 (1–16 months). Relapse occurred in 9 cases an average of 5,20 (2–12) months after the discontinuation. miRNA146a levels at stop were higher in relapsers than in those with sustained remission (relative expression to cel miR39: -3,08 vs -7,87, p=0.009) (n=8 stopped patients, n=1 control). Circulating miRNA223, miRNA16, miRNA155 and miRNA346 levels were comparable in the two drug-cessation groups. SuPar levels were not different in the 12 patients in remission and 7 relapsers, in whom the measurements have been performed so far. Conclusions In RA patients with long-term remission on anti-TNF or IL6R-blocker, elevated level of miRNA146a may indicate a higher risk of relapse after stopping biologics. Further follow-up and the involvement of more patients are currently underway, and this may identify further predictive markers. Toldi G, Kádár G et al. Soluble urokinase plasminogen activator receptor (suPAR) in the asessment of inflammatory activity of rheumatoid arthritis in patients in remission. ClinChem Lab Med 51(2):327–332. 2013 Disclosure of Interest None declared

Although ornithine is a key intermediate in nitrogen metabolism and a precursor of polyamines, its potential to replace high-dose urea-induced phytotoxicity has not been previously studied. To investigate whether ornithine reduces the negative effects of high-concentration nitrogen supply, the effects of standard urea dose (0.33 M) were compared to double dose (0.66 M) and combined urea + ornithine (0.33 M + 0.33 M) as seed priming or foliar application. Although seed-soaking with urea + ornithine had no positive effect, foliar application of ornithine modulated the effects of urea at physiological and metabolite levels. Deep metabolomic analysis revealed that double urea induced a metabolic crisis, especially while it accelerated polyamine catabolism; the urea + ornithine treatment countered this effect by stabilizing polyamine metabolism. This metabolic shift under the combined treatment redirected excess nitrogen from catabolism to polyamine synthesis and conjugation, and also preserved the antioxidant flavonoid pool. Additionally, double urea also disrupted the phenylpropanoid pathway, inducing hormonal stress signalling, and triggered senescence. The present study firstly provides information about the modulatory role of ornithine on foliar urea fertilization of wheat. Ornithine induces a metabolically primed state, which metabolic shift may support efficient nitrogen remobilization before and during grain filling; in addition, it could enhance plant adaptability to subsequent environmental stresses. The results may contribute to the development of sustainable nutrient management practices.