RESUMEN

Strigolactones exhibit dual functionality as regulators of plant architecture and signaling molecules in the rhizosphere. The important model crop rice exudes a blend of different strigolactones from its roots. Here, we identify the inaugural noncanonical strigolactone, 4-oxo-methyl carlactonoate (4-oxo-MeCLA), in rice root exudate. Comprehensive, cross-species coexpression analysis allowed us to identify a cytochrome P450, OsCYP706C2, and two methyl transferases as candidate enzymes for this noncanonical rice strigolactone biosynthetic pathway. Heterologous expression in yeast and Nicotiana benthamiana indeed demonstrated the role of these enzymes in the biosynthesis of 4-oxo-MeCLA, which, expectedly, is derived from carlactone as substrate. The oscyp706c2 mutants do not exhibit a tillering phenotype but do have delayed mycorrhizal colonization and altered root phenotype. This work sheds light onto the intricate complexity of strigolactone biosynthesis in rice and delineates its role in symbiosis and development.

Asunto(s)

Lactonas , Oryza , Proteínas de Plantas , Raíces de Plantas , Oryza/genética , Oryza/metabolismo , Lactonas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/metabolismo , Raíces de Plantas/genética , Vías Biosintéticas , Regulación de la Expresión Génica de las Plantas , Sistema Enzimático del Citocromo P-450/metabolismo , Sistema Enzimático del Citocromo P-450/genética , Mutación , Fenotipo , Micorrizas/metabolismo

RESUMEN

A method for the construction of trifluorinated-5-methylenepyrrolidinone is reported. This strategy combines an acid-catalyzed two-carbon homologation process between ynamides and aldehydes, providing CF3-substituted dienes followed by a metal-free domino hydroamination/isomerization/transamidation sequence, delivering trifluorinated-5-methylenepyrrolidinone stereoselectively.

RESUMEN

We developed a chemoselective metal-free access for the 1,2- and 2,3-semireduction of CF3-N-allenamides. The enamide functionality of CF3-substituted N-allenamides could be efficiently reduced by Et3SiH/BF3·OEt2 in total regioselectivity and good stereoselectivity, whereas DBU promoted the isomerization of the resulting allyl amide leading exclusively to the E-configurated enamide.

RESUMEN

Specialized metabolite (SM) diversification is a core process to plants' adaptation to diverse ecological niches. Here, we implemented a computational mass spectrometry-based metabolomics approach to exploring SM diversification in tissues of 20 species covering Nicotiana phylogenetics sections. To markedly increase metabolite annotation, we created a large in silico fragmentation database, comprising >1 million structures, and scripts for connecting class prediction to consensus substructures. Together, the approach provides an unprecedented cartography of SM diversity and section-specific innovations in this genus. As a case study and in combination with nuclear magnetic resonance and mass spectrometry imaging, we explored the distribution of N-acylnornicotines, alkaloids predicted to be specific to Repandae allopolyploids, and revealed their prevalence in the genus, albeit at much lower magnitude, as well as a greater structural diversity than previously thought. Together, the data integration approaches provided here should act as a resource for future research in plant SM evolution.

Asunto(s)

Metabolómica , Nicotiana , Nicotiana/genética , Aclimatación , Consenso , Bases de Datos Factuales

RESUMEN

We report herein a domino reaction to construct 2-amido-5-fluoropyrroles from CF3-substituted N-allenamides. The in situ generated gem-difluorinated ene-ynamides derived from CF3-substituted N-allenamides, when subjected to silver catalysis with a primary amine, undergo simultaneous hydroamination of the ynamide moiety followed by a 5-endo-trig addition/ß-fluoride elimination sequence, enabling the construction of 2-amido-5-fluoropyrroles. This transformation features excellent functional group compatibility. By employing 2-aminophenols, functionalized benzo-oxazoles were produced.

RESUMEN

The two-faced reactivity of N-allenamides allows regio- and stereo-controlled functionalization at the α-, ß- and γ-positions of the nitrogen atom. The contingency to obtain either proximal or distal adducts makes these substrates essential for the construction of complex heterocyclic scaffolds. This review covers the recent advances made in the development of new methods involving amination and alkoxylation reactions on N-allenamides leading to a broad array of N-heterocycles. The syntheses reported herein are classified based on their reaction type. In addition, mechanistic perceptions are provided for the majority of the discussed transformations.

Asunto(s)

Nitrógeno , Catálisis , Aminación , Nitrógeno/química

RESUMEN

Strigolactones (SLs) are plant hormones exuded in the rhizosphere with a signaling role for the development of arbuscular mycorrhizal (AM) fungi and as stimulants of seed germination of the parasitic weeds Orobanche, Phelipanche, and Striga, the most threatening weeds of major crops worldwide. Phelipanche ramosa is present mainly on rape, hemp, and tobacco in France. P. ramosa 2a preferentially attacks hemp, while P. ramosa 1 attacks rapeseed. The recently isolated cannalactone (14) from hemp root exudates has been characterized as a noncanonical SL that selectively stimulates the germination of P. ramosa 2a seeds in comparison with P. ramosa 1. In the present work, (-)-solanacol (5), a canonical orobanchol-type SL exuded by tobacco and tomato, was established to possess a remarkable selective germination stimulant activity for P. ramosa 2a seeds. Two cannalactone analogues, named (±)-SdL19 and (±)-SdL118, have been synthesized. They have an unsaturated acyclic carbon chain with a tertiary hydroxy group and a methyl or a cyclopropyl group instead of a cyclohexane A-ring, respectively. (±)-SdL analogues are able to selectively stimulate P. ramosa 2a, revealing that these minimal structural elements are key for this selective bioactivity. In addition, (±)-SdL19 is able to inhibit shoot branching in Pisum sativum and Arabidopsis thaliana and induces hyphal branching in the AM fungus Rhizophagus irregularis, like SLs.

Asunto(s)

Arabidopsis , Micorrizas , Orobanchaceae , Orobanche , Striga , Germinación , Compuestos Heterocíclicos con 3 Anillos , Lactonas/química , Lactonas/farmacología , Raíces de Plantas/química , Malezas , Semillas

RESUMEN

The first synthesis of gem-difluorinated ene-ynamides is presented via deprotonation of trifluoromethylated N-allenamides and δ extrusion of fluorine. These highly reactive building blocks, owing to their dual functional groups, offer a unique entry to difluorinated dienes and to stereodefined, monofluoro-substituted dienes. Stereoselective addition to the ynamide moiety led to difluorinated dienes. A stereocontrolled domino δ elimination reaction followed by an addition/elimination sequence from trifluoromethylated N-allenamides provided exclusively stereodefined monofluorinated ene-ynamides.

RESUMEN

A synthesis of new-to-nature aza-iridoids via ynamides is presented. ZrCl4 proved to be the best acid to perform this transformation. Various ynamides were accommodated, and seco-iridoids could be obtained as well. Aza-iridoids were infiltrated into leaves of Scrophularia Nodosa, an iridoid-producing plant species. High-resolution mass spectrometry coupled to computational metabolomic approaches was employed for the detection of aza-iridoid bioconversion products.

Asunto(s)

Iridoides , Scrophularia , Iridoides/química , Espectrometría de Masas , Hojas de la Planta , Scrophularia/química

RESUMEN

N-Allenamides, substituted by an ester at the γ-position, were obtained through addition of terminal ynamides with ethyl diazoacetate under copper catalysis for the first time. Regio- and stereoselective hydroamination of those activated N-allenamides provided exclusively E-configured captodative enamimes through a one-pot anti-Michael addition. Numerous ynamides as well as various secondary amines were adapted in this process.

Asunto(s)

Aminas , Cobre , Catálisis , Estereoisomerismo

RESUMEN

A copper-mediated coupling reaction between ynamides and diazo-compounds to produce N-allenamides is reported for the first time. This method enables facile and rapid access to terminal N-allenamides by using commercially available TMS-diazomethane with wide functional group compatibility on the nitrogen. Furthermore, the ubiquity of molecules containing a fluorine moiety in medicine, in agricultural, and material science requires the continuous search of new building blocks, including this unique surrogate. The CuI/diazo protocol was successfully applied to the synthesis of fluorine-substituted N-allenamides. DFT calculations provided insights in the mechanism involved.

Asunto(s)

Cobre , Flúor , Compuestos Azo , Catálisis

RESUMEN

The significance of molecules containing difluoromethyl groups is driven by their potential applications in pharmaceutical and agrochemical science. Methods for the incorporation of lightly fluorinated groups such as CF2H have been less well developed. Here we report the use of difluorinated diazoacetone as a practical reagent for the direct synthesis of CF2H-substituted 2-amidofurans through addition to ynamides. These newly designed difluorinated amidofurans were elaborated to create new nitrogen-containing frameworks that would be challenging to obtain otherwise.

RESUMEN

Increased metabolism is one of the main causes for evolution of herbicide resistance in weeds, a major challenge for sustainable food production. The molecular drivers of this evolution are poorly understood. We tested here the hypothesis that a suitable context for the emergence of herbicide resistance could be provided by plant enzymes with high innate promiscuity with regard to their natural substrates. A selection of yeast-expressed plant cytochrome P450 enzymes with well documented narrow to broad promiscuity when metabolizing natural substrates was tested for herbicide metabolism competence. The positive candidate was assayed for capacity to confer herbicide tolerance in Arabidopsis thaliana. Our data demonstrate that Arabidopsis thaliana CYP706A3, with the most promiscuous activity on monoterpenes and sesquiterpenes for flower defence, can also oxidize plant microtubule assembly inhibitors, dinitroanilines. Ectopic overexpression of CYP706A3 confers dinitroaniline resistance. We show, in addition, that the capacity to metabolize dinitroanilines is shared by other members of the CYP706 family from plants as diverse as eucalyptus and cedar. Supported by three-dimensional (3D) modelling of CYP706A3, the properties of enzyme active site and substrate access channel are discussed together with the shared physicochemical properties of the natural and exogenous substrates to explain herbicide metabolism.

Asunto(s)

Arabidopsis , Herbicidas , Arabidopsis/genética , Sistema Enzimático del Citocromo P-450/genética , Resistencia a los Herbicidas/genética , Herbicidas/farmacología , Malezas/genética

RESUMEN

N-Acyliminium ions generated from enamidyl vinyl ketones provided cyclopentenoid-fused diazepines diastereoselectively using BF3·Et2O in one pot through a domino N-acyliminium ion trapping/Nazarov reaction, simultaneously generating three new stereogenic centers. The particular structural design of the cross-conjugated dienone dictates the torquoselectivity observed in this polarized Nazarov reaction. Various N-bridgehead polycyclic scaffolds of putative pharmacological interest were obtained. Cyclic voltammetry was used to support the preferred reaction sequence within this domino reaction.

RESUMEN

Flowers are essential but vulnerable plant organs, exposed to pollinators and florivores; however, flower chemical defenses are rarely investigated. We show here that two clustered terpene synthase and cytochrome P450 encoding genes (TPS11 and CYP706A3) on chromosome 5 of Arabidopsis (Arabidopsis thaliana) are tightly coexpressed in floral tissues, upon anthesis and during floral bud development. TPS11 was previously reported to generate a blend of sesquiterpenes. By heterologous coexpression of TPS11 and CYP706A3 in yeast (Saccharomyces cerevisiae) and Nicotiana benthamiana, we demonstrate that CYP706A3 is active on TPS11 products and also further oxidizes its own primary oxidation products. Analysis of headspace and soluble metabolites in cyp706a3 and 35S:CYP706A3 mutants indicate that CYP706A3-mediated metabolism largely suppresses sesquiterpene and most monoterpene emissions from opening flowers, and generates terpene oxides that are retained in floral tissues. In flower buds, the combined expression of TPS11 and CYP706A3 also suppresses volatile emissions and generates soluble sesquiterpene oxides. Florivory assays with the Brassicaceae specialist Plutella xylostella demonstrate that insect larvae avoid feeding on buds expressing CYP706A3 and accumulating terpene oxides. Composition of the floral microbiome appears also to be modulated by CYP706A3 expression. TPS11 and CYP706A3 simultaneously evolved within Brassicaceae and form the most versatile functional gene cluster described in higher plants so far.plantcell;31/12/2947/FX1F1fx1.

Asunto(s)

Transferasas Alquil y Aril/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Sistema Enzimático del Citocromo P-450/metabolismo , Flores/metabolismo , Terpenos/antagonistas & inhibidores , Transferasas Alquil y Aril/genética , Animales , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/microbiología , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Sistema Enzimático del Citocromo P-450/química , Sistema Enzimático del Citocromo P-450/genética , Flores/genética , Flores/microbiología , Expresión Génica , Larva , Microbiota , Modelos Moleculares , Simulación del Acoplamiento Molecular , Monoterpenos/metabolismo , Mariposas Nocturnas , Familia de Multigenes , Filogenia , Sesquiterpenos/metabolismo , Terpenos/química , Terpenos/metabolismo , Nicotiana/metabolismo , Levaduras/metabolismo

RESUMEN

BACKGROUND: Jasmonate (JA) signaling and functions have been established in rice development and response to a range of biotic or abiotic stress conditions. However, information on the molecular actors and mechanisms underlying turnover of the bioactive jasmonoyl-isoleucine (JA-Ile) is very limited in this plant species. RESULTS: Here we explored two gene families in rice in which some members were described previously in Arabidopsis to encode enzymes metabolizing JA-Ile hormone, namely cytochrome P450 of the CYP94 subfamily (CYP94, 20 members) and amidohydrolases (AH, 9 members). The CYP94D subclade, of unknown function, was most represented in the rice genome with about 10 genes. We used phylogeny and gene expression analysis to narrow the study to candidate members that could mediate JA-Ile catabolism upon leaf wounding used as mimic of insect chewing or seedling exposure to salt, two stresses triggering jasmonate metabolism and signaling. Both treatments induced specific transcriptional changes, along with accumulation of JA-Ile and a complex array of oxidized jasmonate catabolites, with some of these responses being abolished in the JASMONATE RESISTANT 1 (jar1) mutant. However, upon response to salt, a lower dependence on JAR1 was evidenced. Dynamics of CYP94B5, CYP94C2, CYP94C4 and AH7 transcripts matched best the accumulation of JA-Ile catabolites. To gain direct insight into JA-Ile metabolizing activities, recombinant expression of some selected genes was undertaken in yeast and bacteria. CYP94B5 was demonstrated to catalyze C12-hydroxylation of JA-Ile, whereas similarly to its Arabidopsis bi-functional homolog IAR3, AH8 performed cleavage of JA-Ile and auxin-alanine conjugates. CONCLUSIONS: Our data shed light on two rice gene families encoding enzymes related to hormone homeostasis. Expression data along with JA profiling and functional analysis identifies likely actors of JA-Ile catabolism in rice seedlings. This knowledge will now enable to better understand the metabolic fate of JA-Ile and engineer optimized JA signaling under stress conditions.

RESUMEN

An operationally simple synthesis of activated ynesulfonamides and enesulfonamides is described. Ynesulfonamides can be obtained through reaction of sulfonylamides with activated bromoalkynes and Triton B in a short time at room temperature. Likewise, terminal alkynes react with sulfonylamides to provide enesulfonamides. Z/E enesulfonamides can be transformed exclusively into E enesulfonamides.

RESUMEN

Two unprecedented domino reactions are described, starting from ketospiro-enesulfonamides. By treatment with ZrCl4 and allylsilane, an intramolecular electrophilic aromatic substitution and subsequent allylation is observed. By treatment with TiCl4 and allylsilane, a double enamine-type reaction takes place, thus creating simultaneously four contiguous stereogenic centers diastereoselectively.

RESUMEN

Enamides equipped with N-acyliminium ion precursors were obtained through reduction of ynamides tethered to N-imides. Intramolecular TMSOTf-mediated trapping of N-acyliminium ions provided a variety of polyfunctionalized medium-sized diaza-heterocycles of putative pharmacological interest.

RESUMEN

Spontaneous spirocyclization of keto-sulfonamides via ynamides through a one-pot process is presented. Push-pull ynamides were obtained through Michael addition/elimination without Cu. The obtained azaspiro compounds are building blocks for indole alkaloids. Theoretical studies provide insights into the mechanism of the formal Conia-ene reaction.