RESUMO
Plant responses to the environment and microorganisms, including arbuscular mycorrhizal fungi, involve complex hormonal interactions. It is known that abscisic acid (ABA) and ethylene may be involved in the regulation of arbuscular mycorrhiza (AM) and that part of the detrimental effects of ABA deficiency in plants is due to ethylene overproduction. In this study, we aimed to determine whether the low susceptibility to mycorrhizal colonization in ABA-deficient mutants is due to high levels of ethylene and whether AM development is associated with changes in the steady-state levels of transcripts of genes involved in the biosynthesis of ethylene and ABA. For that, tomato (Solanum lycopersicum) ethylene overproducer epinastic (epi) mutant and the ABA-deficient notabilis (not) and sitiens (sit) mutants, in the same Micro-Tom (MT) genetic background, were inoculated with Rhizophagus clarus, and treated with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG). The development of AM, as well as the steady-state levels of transcripts involved in ethylene (LeACS2, LeACO1 and LeACO4) and ABA (LeNCED) biosynthesis, was determined. The intraradical colonization in epi, not and sit mutants was significantly reduced compared to MT. The epi mutant completely restored the mycorrhizal colonization to the levels of MT with the application of 10 µM of AVG, probably due to the inhibition of the ACC synthase gene expression. The steady-state levels of LeACS2 and LeACO4 transcripts were induced in mycorrhizal roots of MT, whereas the steady-state levels of LeACO1 and LeACO4 transcripts were significantly induced in sit, and the steady-state levels of LeNCED transcripts were significantly induced in all genotypes and in mycorrhizal roots of epi mutants treated with AVG. The reduced mycorrhizal colonization in sit mutants seems not to be limited by ethylene production via ACC oxidase regulation. Both ethylene overproduction and ABA deficiency impaired AM fungal colonization in tomato roots, indicating that, besides hormonal interactions, a fine-tuning of each hormone level is required for AM development.
Assuntos
Ácido Abscísico/metabolismo , Etilenos/metabolismo , Fungos/crescimento & desenvolvimento , Micorrizas/crescimento & desenvolvimento , Solanum lycopersicum/metabolismo , Ácido Abscísico/biossíntese , Aminoácido Oxirredutases/antagonistas & inibidores , Etilenos/biossíntese , Glicina/análogos & derivados , Glicina/farmacologia , Liases/antagonistas & inibidores , Solanum lycopersicum/genética , Solanum lycopersicum/microbiologia , Micorrizas/metabolismo , Raízes de Plantas/microbiologiaRESUMO
Bioassay-directed fractionation of a methyl ethyl ketone extract of the roots of Endlicheria aff. resulted in the isolation of four new neolignans (1-4) and eight known compounds, namely, canellin A (5), canellin C (6), 3'-methoxyguianin (7), (7S,8R,1'S,5'S,6'R)-Delta(2',8')-3',6'-dihydroxy-5'-methoxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan (8), armenin-B (9), dillapiole (10), 1-allyl-2,6-dimethoxy-3,4-methylenedioxybenzene (11), and omega-hydroxyisodillapiole (12). The structures of the new compounds (1-4) were established as (7S,8R,1'S,5'S,6'R)-Delta(2',8')-5',6'-dihydroxy-3'-methoxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan, (7S,8R,1'S,5'S,6'R)-Delta(2',8')-3',5',6'-trihydroxy-3,4-methylenedioxy-4'-oxo-8.1',7.5'-neolignan, 2,4-dimethoxy-5,6-methylenedioxy-1-(2-propenyl)benzene, and 2,6-dimethoxy-3,4-methylenedioxycinnamyl alcohol, respectively, on the basis of spectroscopic interpretation.
Assuntos
DNA Polimerase beta/antagonistas & inibidores , Inibidores Enzimáticos/isolamento & purificação , Lauraceae/química , Lignanas/isolamento & purificação , Liases/antagonistas & inibidores , Plantas Medicinais/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Lignanas/química , Lignanas/farmacologia , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Peru , Raízes de Plantas/química , EstereoisomerismoRESUMO
Bioassay-directed fractionation of a butanone extract of Monochaetum vulcanicum resulted in the isolation of a new triterpene (1) and four known compounds, ursolic acid (2), 2alpha-hydroxyursolic acid (3), 3-(p-coumaroyl)ursolic acid (4), and beta-sitosteryl-beta-d-galactoside (5). The structure of the new compound 1 was established as 3beta-acetoxy-2alpha-hydroxyurs-12-en-28-oic acid on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical derivatization. Compounds 1-3 and 5 exhibited polymerase beta lyase activity.
Assuntos
DNA Polimerase beta/antagonistas & inibidores , Inibidores Enzimáticos/isolamento & purificação , Liases/antagonistas & inibidores , Melastomataceae/química , Plantas Medicinais/química , Triterpenos/isolamento & purificação , Acetilação , Costa Rica , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Concentração Inibidora 50 , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Estereoisomerismo , Triterpenos/química , Triterpenos/farmacologia , Ácido UrsólicoRESUMO
Bioassay-directed fractionation of a n-hexane extract of Couepia polyandra using an assay to detect inhibitors of the lyase activity of DNA polymerase beta resulted in the isolation of the new triterpene 3beta,16beta,23-triacetoxyolean-12-en-28-oic acid (1) and four known compounds, oleanolic acid, betulinic acid, stigmasterol, and beta-sitosterol. The structure of the new compound was established on the basis of extensive 1D and 2D NMR spectroscopic interpretation. All five compounds inhibited DNA polymerase beta lyase activity.
Assuntos
Chrysobalanaceae/química , DNA Polimerase beta/antagonistas & inibidores , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia , Ácido Oleanólico/análogos & derivados , Ácido Oleanólico/isolamento & purificação , Ácido Oleanólico/farmacologia , Plantas Medicinais/química , Triterpenos/isolamento & purificação , Triterpenos/farmacologia , Sequência de Bases , Inibidores Enzimáticos/química , Liases/antagonistas & inibidores , México , Dados de Sequência Molecular , Ressonância Magnética Nuclear Biomolecular , Ácido Oleanólico/química , Triterpenos Pentacíclicos , Casca de Planta/química , Caules de Planta/química , Triterpenos/química , Ácido BetulínicoRESUMO
The basis for the clinical variation in response to lead exposure in children is not well understood. We studied selected children from a large lead screening program in whom elevation of red cell protoporphyrin concentration (a measure of inhibition of the enzyme ferrochelatase) was markedly above or below average for a given blood lead level. We then measured the activity of the enzyme amino levulinate dehydratase in 306 of these children, and found that ALA-d activity was lower in children with higher protoporphyrin elevation, independent of the effects of lead. This observation, coupled with reports in the literature of families with ALA-d deficiencies and elevated red cell protoporphyrin values, makes likely a genetic basis for some of the variation in susceptibility to lead. The mechanism by which the two effects are associated remains unknown.