Unser 10. Leibniz Plant Biochemistry Symposium am 7. und 8. Mai war ein großer Erfolg. Thematisch ging es in diesem Jahr um neue Methoden und Forschungsansätze der Naturstoffchemie. Die exzellenten Vorträge über Wirkstoffe…
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…
Mekkaoui, K.; Baral, R.; Smith, F.; Klein, M.; Feussner, I.; Hause, B.;Unraveling the role of 12-cis-oxo-phytodienoic acid in the wound response of Arabidopsis thaliana: Insights from transcriptomic and complementation studiesbioRxiv(2024)DOI: 10.1101/2024.03.22.586262
In addition to jasmonoyl-isoleucine (JA-Ile), a well-established signaling molecule for plant growth and defense, its precursor, cis-12-oxo-phytodienoic acid (OPDA), is thought to possess independent signaling functions. Its perception in vascular plants is still uncharacterized. Several OPDA functions in Arabidopsis were inferred from a mutant that is affected in the function of the OPDA REDUCTASE3 (OPR3), catalyzing the conversion of OPDA within peroxisomes. Recently, opr3 plants were found to accumulate JA-Ile via a cytosolic OPR2-mediated bypass. Given the uncoupling of OPDA and JA biosynthesis in the JA-deficient mutant opr2opr3, potential OPDA signaling was investigated by a transcriptome approach comparing wild type, opr2opr3 and the JA- and OPDA-deficient mutantallene oxide synthase. Dissecting the wound response of seedlings revealed that OPDA lacked a transcriptional signature, and that previously characterized OPDA-response genes were wound-induced independently of OPDA. Exogenous application of OPDA to opr2opr3 seedlings led to JA-Ile formation and signaling even in absence of OPR2 and OPR3 and resulted in activation of sulfur assimilation. These divergent responses to endogenously synthesized and applied OPDA suggest a compartmentalization of endogenous OPDA which was investigated by a trans-organellar complementation approach. OPR3 complemented the opr2opr3 mutant in terms of fertility and wound-induced JA-Ile production irrespective of its subcellular localization. In vitro enzymatic activity of OPR3, however, showed conversion of OPDA and 4,5-didehydro-JA (4,5-ddh-JA), therefore not allowing to conclude which compound is translocated. Dissecting the conversion of either OPDA or 4,5-ddh-JA by OPR2 and OPR1 organelle variants pointed to a strong OPDA compartmentalization supporting its lacking signaling capacity.
Preprints
Rajamanickam, K.; Schönhof, M. D.; Hause, B.; Sauter, M.;PSK signaling controls ABA homeostasis and signaling genes and maintains shoot growth under osmotic stressbioRxiv(2021)DOI: 10.1101/2020.10.20.347674
Water deficit impairs growth and survival of plants. Many water stress responses are under control of abscisic acid (ABA) but little is known about growth control under osmotic stress. Based on the previously described growth-promoting activity of the peptide hormone phytosulfokine (PSK), we hypothesized that it may contribute to growth regulation under water stress conditions. To test this hypothesis, we analyzed the Arabidopsis thaliana PSK receptor (PSKR) null mutant pskr1-3 pskr2-1 under mannitol and drought stress. In particular under mild water stress, fresht weight and photosynthetic efficiency were more reduced in pskr1-3 pskr2-1 than in wild type. Hydroponic and grafting experiments showed that PSKR signaling was not required for long-distance signaling from mannitol-stressed roots to shoot but rather for cell growth promotion in the shoot. Unlike wild type, pskr1-3 pskr2-1 shoots did not accumulate ABA in response to mannitol, showed misregulation of ABA synthesis genes and elevated expression of ABI1 and ABI2, repressors of ABA signaling whereas application of ABA partially reversed shoot growth inhibition by mannitol in pskr1-3 pskr2-1. In turn, mannitol and ABA induced expression of PSK3 and PSKR1, and ABA promoted expression of PSK2 and PSK4 revealing feedback regulatory loops between PSKR and osmotic stress signaling.HighlightPhytosulfokine receptor signaling regulates ABA synthesis and signaling genes and promotes ABA accumulation in the shoot of water-stressed plants and maintains leaf growth and photosynthetic efficiency which ensures plant health.