RESUMO
Plants adapt to abiotic and biotic stresses by activating abscisic acid-mediated (ABA) abiotic stress-responsive and salicylic acid-(SA) or jasmonic acid-mediated (JA) biotic stress-responsive pathways, respectively. Although the abiotic stress-responsive pathway interacts antagonistically with the biotic stress-responsive pathways, the mechanisms that regulate these pathways remain largely unknown. In this study, we provide insight into the function of vascular plant one-zinc-finger proteins (VOZs) that modulate various stress responses in Arabidopsis. The expression of many stress-responsive genes was changed in the voz1voz2 double mutant under normal growth conditions. Consistent with altered stress-responsive gene expression, freezing- and drought-stress tolerances were increased in the voz1voz2 double mutant. In contrast, resistance to a fungal pathogen, Colletotrichum higginsianum, and to a bacterial pathogen, Pseudomonas syringae, was severely impaired. Thus, impairing VOZ function simultaneously conferred increased abiotic tolerance and biotic stress susceptibility. In a chilling stress condition, both the VOZ1 and VOZ2 mRNA expression levels and the VOZ2 protein level gradually decreased. VOZ2 degradation during cold exposure was completely inhibited by the addition of the 26S proteasome inhibitor, MG132, a finding that suggested that VOZ2 degradation is dependent on the ubiquitin/26S proteasome system. In voz1voz2, ABA-inducible transcription factor CBF4 expression was enhanced significantly even under normal growth conditions, despite an unchanged endogenous ABA content. A finding that suggested that VOZs negatively affect CBF4 expression in an ABA-independent manner. These results suggest that VOZs function as both negative and positive regulators of the abiotic and biotic stress-responsive pathways, and control Arabidopsis adaptation to various stress conditions.
Assuntos
Ácido Abscísico/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Ácido Salicílico/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/microbiologia , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Colletotrichum/fisiologia , Inibidores de Cisteína Proteinase/farmacologia , Regulação para Baixo , Secas , Congelamento , Perfilação da Expressão Gênica , Leupeptinas/farmacologia , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/microbiologia , Folhas de Planta/fisiologia , Estômatos de Plantas/efeitos dos fármacos , Estômatos de Plantas/genética , Estômatos de Plantas/microbiologia , Estômatos de Plantas/fisiologia , Plantas Geneticamente Modificadas , Pseudomonas syringae/fisiologia , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/microbiologia , Plântula/fisiologia , Estresse Fisiológico , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Dedos de ZincoRESUMO
Salsolinol (1), a tetrahydroisoquinoline alkaloid, was isolated from the marine sponge Xestospongia cf. vansoesti collected in Indonesia as a proteasome inhibitor, along with three salsolinol derivatives, norsalsolinol (2), cis-4-hydroxysalsolinol (3), and trans-4-hydroxysalsolinol (4). Compounds 1 and 2 inhibited the chymotrypsin-like activity of the proteasome with IC(50) values of 50 and 32 µg/ml, respectively, but 3 and 4 showed no inhibitory effect even at 100 µg/ml.
Assuntos
Alcaloides/isolamento & purificação , Isoquinolinas/isolamento & purificação , Inibidores de Proteassoma , Tetra-Hidroisoquinolinas/isolamento & purificação , Xestospongia/química , Alcaloides/química , Alcaloides/farmacologia , Animais , Células HeLa , Humanos , Isoquinolinas/química , Isoquinolinas/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Tetra-Hidroisoquinolinas/química , Tetra-Hidroisoquinolinas/farmacologiaRESUMO
Three new labdane-type diterpenoids, viteagnusins F, G, and H, were isolated from the hexane extract of fruit (chasteberry) of Vitex agnus-castus L. (Verbenaceae) along with seven known compounds including four labdane-type diterpenoids, one norlabdane-type diterpenoid, one aromadendrane-type sesquiterpenoid, and one flavonoid. The chemical structures of the three new labdane-type diterpenoids were determined on the basis of spectroscopic data as well as chemical evidence.