Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Dinesh, D. C.; Calderón Villalobos, L. I. A.; Abel, S.;Structural Biology of Nuclear Auxin ActionTrends Plant Sci.21302-316(2016)DOI: 10.1016/j.tplants.2015.10.019
Auxin coordinates plant development largely via hierarchical control of gene expression. During the past decades, the study of early auxin genes paired with the power of Arabidopsis genetics have unraveled key nuclear components and molecular interactions that perceive the hormone and activate primary response genes. Recent research in the realm of structural biology allowed unprecedented insight into: (i) the recognition of auxin-responsive DNA elements by auxin transcription factors; (ii) the inactivation of those auxin response factors by early auxin-inducible repressors; and (iii) the activation of target genes by auxin-triggered repressor degradation. The biophysical studies reviewed here provide an impetus for elucidating the molecular determinants of the intricate interactions between core components of the nuclear auxin response module.
Publikation
Hettwer, K.; Böttcher, C.; Frolov, A.; Mittasch, J.; Albert, A.; von Roepenack-Lahaye, E.; Strack, D.; Milkowski, C.;Dynamic metabolic changes in seeds and seedlings of Brassica napus (oilseed rape) suppressing UGT84A9 reveal plasticity and molecular regulation of the phenylpropanoid pathwayPhytochemistry12446-57(2016)DOI: 10.1016/j.phytochem.2016.01.014
In Brassica napus, suppression of the key biosynthetic enzyme UDP-glucose:sinapic acid glucosyltransferase (UGT84A9) inhibits the biosynthesis of sinapine (sinapoylcholine), the major phenolic component of seeds. Based on the accumulation kinetics of a total of 158 compounds (110 secondary and 48 primary metabolites), we investigated how suppression of the major sink pathway of sinapic acid impacts the metabolome of developing seeds and seedlings. In UGT84A9-suppressing (UGT84A9i) lines massive alterations became evident in late stages of seed development affecting the accumulation levels of 58 secondary and 7 primary metabolites. UGT84A9i seeds were characterized by decreased amounts of various hydroxycinnamic acid (HCA) esters, and increased formation of sinapic and syringic acid glycosides. This indicates glycosylation and β-oxidation as metabolic detoxification strategies to bypass intracellular accumulation of sinapic acid. In addition, a net loss of sinapic acid upon UGT84A9 suppression may point to a feedback regulation of HCA biosynthesis. Surprisingly, suppression of UGT84A9 under control of the seed-specific NAPINC promoter was maintained in cotyledons during the first two weeks of seedling development and associated with a reduced and delayed transformation of sinapine into sinapoylmalate. The lack of sinapoylmalate did not interfere with plant fitness under UV-B stress. Increased UV-B radiation triggered the accumulation of quercetin conjugates whereas the sinapoylmalate level was not affected.
Publikation
Fobofou, S. A. T.; Harmon, C. R.; Lonfouo, A. H. N.; Franke, K.; Wright, S. M.; Wessjohann, L. A.;Prenylated phenyl polyketides and acylphloroglucinols from Hypericum peplidifoliumPhytochemistry124108-113(2016)DOI: 10.1016/j.phytochem.2016.02.003
In search for new or chemo-taxonomically relevant bioactive compounds from chemically unexplored Hypericum species, four previously undescribed natural products, named peplidiforones A–D were isolated and characterized from Hypericum peplidifolium A. Rich., together with six known compounds. The structures of all compounds were elucidated by extensive 1D- and 2D-NMR experiments, high resolution mass spectrometric analyses (HR-MS), and by comparison with data reported in the literature. Seven of these compounds are phenyl polyketides while three are acylphloroglucinol type compounds. Peplidiforone C, which possesses an unusual carbon skeleton consisting of a furan ring substituted by a 2,2-dimethylbut-3-enoyl moiety, is the first example of a prenylated furan derivative isolated from the genus Hypericum. The cytotoxicity, antifungal, and anti-herpes simplex virus type 1 (HSV-1) activities of extracts and compounds are described.
Publikation
Floková, K.; Feussner, K.; Herrfurth, C.; Miersch, O.; Mik, V.; Tarkowská, D.; Strnad, M.; Feussner, I.; Wasternack, C.; Novák, O.;A previously undescribed jasmonate compound in flowering Arabidopsis thaliana – The identification of cis-(+)-OPDA-IlePhytochemistry122230-237(2016)DOI: 10.1016/j.phytochem.2015.11.012
Jasmonates (JAs) are plant hormones that integrate external stress stimuli with physiological responses. (+)-7-iso-JA-L-Ile is the natural JA ligand of COI1, a component of a known JA receptor. The upstream JA biosynthetic precursor cis-(+)-12-oxo-phytodienoic acid (cis-(+)-OPDA) has been reported to act independently of COI1 as an essential signal in several stress-induced and developmental processes. Wound-induced increases in the endogenous levels of JA/JA-Ile are accompanied by two to tenfold increases in the concentration of OPDA, but its means of perception and metabolism are unknown. To screen for putative OPDA metabolites, vegetative tissues of flowering Arabidopsis thaliana were extracted with 25% aqueous methanol (v/v), purified by single-step reversed-phase polymer-based solid-phase extraction, and analyzed by high throughput mass spectrometry. This enabled the detection and quantitation of a low abundant OPDA analog of the biologically active (+)-7-iso-JA-L-Ile in plant tissue samples. Levels of the newly identified compound and the related phytohormones JA, JA-Ile and cis-(+)-OPDA were monitored in wounded leaves of flowering Arabidopsis lines (Col-0 and Ws) and compared to the levels observed in Arabidopsis mutants deficient in the biosynthesis of JA (dde2-2, opr3) and JA-Ile (jar1). The observed cis-(+)-OPDA-Ile levels varied widely, raising questions concerning its role in Arabidopsis stress responses.