Structure-activity relationships of synthetic analogs of jasmonic acid and coronatine on induction of benzo[c]phenanthridine alkaloid accumulation in Eschscholzia californica cell cultures

A facile test system based on the accumulation of benzo[c]phenanthridine alkaloids in Eschscholzia californica cell suspension culture (an indicator of defense gene activation) has been used to analyze a series of synthetic compounds for elicitor-like activity. Of the 200 jasmonic acid and coronatine analogs tested with this system, representative results obtained with 49 of them are presented here. The following can be summarized concerning structure-actvity relationships: there is a large degree of plasticity allowed at the C-3 of jasmonic acid in the activation of defense genes. The carbonyl moiety is not strictly required, but exocyclic double bond character appears necessary. The pentenyl side chain at C-2 cannot tolerate bulky groups at the terminal carbon and still be biologically active. Substitutions to the C-1' position are tolerated if they can potentially undergo beta-oxidation. Either an alkanoic acid or methyl ester is required at c-l, or a side chain that can be shortened by beta-oxidation or by peptidase hydrolysis. Coronatine and various derivatives thereof are not as effective as jasmonic acid, and derivatives in inducing benzo[c]phenanthridine alkaloid accumulation. Jasmonic acid rather than the octadecanoic precursors is therefore considered to be a likely signal transducer of defense gene activation in planta

Identification of phytochelatin-related peptides in maize seedlings exposed to cadmium and obtained enzymatically in vitro

International audienceAn analytical strategy based on the sensitivity of electrospray tandem mass spectrometry following a simplified and reproducible sample preparation procedure was evaluated for the determination of Cd-induced phytochelatins (PC) and related peptides in four maize varieties. In addition to the three known families of PC (PC, desGly-PC and iso-PC(Glu)) that were observed, novel PC and desGly-PC homologues lacking the N-terminal ?-linked Glu were isolated from maize root extracts for the first time. Additionally the complete sequence of iso-PC3(Glu) was determined by tandem mass spectrometry. Peptides obtained in vivo and in vitro as the result of the reaction of glutathione with the enzyme phytochelatin synthase were compared. Minor forms detected from in vitro reactions include compounds with intramolecular or intermolecular disulfide bonds resulting from the oxidation of SH groups, phytochelatin homologues lacking the N-terminal ?-linked Glu, and new PC-related peptides with a Cys-Cys motif. Since peptides lacking a ?Glu residue could be generated as artifacts in electrospray mass spectrometry, the application of capillary electrophoresis with online electrospray mass spectrometry allowed the separation and detection of such peptides as endogenous molecules present in planta and as products of in vitro reactions. © 2001 Elsevier Science Ltd

How do vascular plants perform photosynthesis in extreme environments? An integrative ecophysiological and biochemical story

In this work, we review the physiological and molecular mechanisms that allow vascular plants to perform photosynthesis in extreme environments, such as deserts, polar and alpine ecosystems. Specifically, we discuss the morpho/anatomical, photochemical and metabolic adaptive processes that enable a positive carbon balance in photosynthetic tissues under extreme temperatures and/or severe water-limiting conditions in C3 species. Nevertheless, only a few studies have described the in situ functioning of photoprotection in plants from extreme environments, given the intrinsic difficulties of fieldwork in remote places. However, they cover a substantial geographical and functional range, which allowed us to describe some general trends. In general, photoprotection relies on the same mechanisms as those operating in the remaining plant species, ranging from enhanced morphological photoprotection to increased scavenging of oxidative products such as reactive oxygen species. Much less information is available about the main physiological and biochemical drivers of photosynthesis: stomatal conductance (gs), mesophyll conductance (gm) and carbon fixation, mostly driven by RuBisCO carboxylation. Extreme environments shape adaptations in structures, such as cell wall and membrane composition, the concentration and activation state of Calvin–Benson cycle enzymes, and RuBisCO evolution, optimizing kinetic traits to ensure functionality. Altogether, these species display a combination of rearrangements, from the whole-plant level to the molecular scale, to sustain a positive carbon balance in some of the most hostile environments on Earth.Fil: Fernández Marín, Beatriz. Universidad de La Laguna; EspañaFil: Gulías, Javier. Institut D´investigacion Sanitaria Llles Balears (idlsba);Fil: Figueroa, Carlos Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Iñiguez, Concepción. Institut D´investigacion Sanitaria Llles Balears (idlsba);Fil: Clemente Moreno, María J.. Institut D´investigacion Sanitaria Llles Balears (idlsba);Fil: Nunes Nesi, Adriano. Universidade Federal de Viçosa.; BrasilFil: Fernie, Alisdair R.. Max Planck Institute Of Molecular Plant Physiology; AlemaniaFil: Cavieres, Lohengrin A.. Universidad de Concepción; ChileFil: Bravo, León A.. Universidad de La Frontera; ChileFil: García Plazaola, José I.. Universidad del País Vasco; EspañaFil: Gago, Jorge. Institut D´investigacion Sanitaria Llles Balears (idlsba)