RESUMEN
OBJECTIVE: To obtain micro propagated Uncaria tomentosa plantlets with enhanced secondary metabolites production, long-term responses to salicylic acid (SA) pre-treatments at 1 and 100 µM were evaluated after propagation of the plantlets in a SA-free medium. RESULTS: SA pre-treatments of single node cuttings OF U. tomentosa produced long-term responses in microplants grown for 75 days in a SA-free medium. Reduction in survival rate, root formation, and stem elongation were observed only with 100 µM SA pre-treatments with respect to the control (0 + DMSO).Both pre-treatments enhanced H2O2 and inhibited superoxide dismutase and catalase activities, while guaiacol peroxidase was increased only with 1 µM SA. Also, both pre-treatments increased total monoterpenoid oxindole alkaloids by ca. 55 % (16.5 mg g(-1) DW), including isopteropodine, speciophylline, mitraphylline, isomitraphylline, rhynchopylline, and isorhynchopylline; and flavonoids by ca. 21 % (914 µg g(-1) DW), whereas phenolic compounds were increased 80 % (599 µg g(-1) DW) at 1 µM and 8.2 % (359 µg g(-1) DW) at 100 µM SA. CONCLUSION: Pre-treatment with 1 µM SA of U.tomentosa microplants preserved the survival rate and increased oxindole alkaloids, flavonoids, and phenolic compounds in correlation with H2O2 and peroxidase activity enhancements, offering biotechnological advantages over non-treated microplants.
Asunto(s)
Antioxidantes/metabolismo , Uña de Gato/efectos de los fármacos , Ácido Salicílico/metabolismo , Metabolismo Secundario/efectos de los fármacos , Alcaloides/análisis , Uña de Gato/enzimología , Uña de Gato/crecimiento & desarrollo , Uña de Gato/metabolismo , Medios de Cultivo/química , Flavonoides/análisis , Peróxido de Hidrógeno/análisis , Indoles/análisis , Monoterpenos/análisis , Oxindoles , Fenoles/análisis , Raíces de Plantas/crecimiento & desarrollo , Tallos de la Planta/crecimiento & desarrollo , Análisis de SupervivenciaRESUMEN
The activity and gene expression of strictosidine-related enzymes in Uncaria tomentosa root cultures exposed to oxidative stress were studied. Elicitation with 0.2 mM hydrogen peroxide (H2 O2 ) or a combination of 0.8 mM buthionine sulfoximine and 0.2 mM jasmonic acid (BSO-JA) increased peroxidase activities by twofold at Day 8 and glutathione reductase by 1.4-fold at Day 5 in H2 O2 elicited cultures respect to the control. Production of monoterpenoid oxindole alkaloids (MOA), 3α-dihydrocadambine, and dolichantoside was stimulated after H2 O2 elicitation, reaching levels of 886.4 ± 23.6, 847.7 ± 25.4, and 87.5 ± 7.2 µg/g DW, at Day 8 which were 1.7-, 2.1-, and 2.3-fold higher relative to control. BSO-JA elicited cultures produced about twice alkaloids than H2 O2 -treated cultures, following a biphasic pattern with maxima at 0.5 and 8 days. Alkaloid production was preceded by increase in strictosidine synthase (STR) and strictosidine glucosidase (SGD) activities. After elicitation with H2 O2 or BSO-JA, the STR activity (pKat/mg protein) increased by 1.9-fold (93.8 ± 17.8 at 24 h) or 2.5-fold (102.4 ± 2.2 at 6 h) and the SGD activity (pKat/mg protein) by 2.8-fold (245.2 ± 14.4 at 6 h) or 4.2-fold (421.2 ± 1.8 at 18 h) relative to control. STR and SGD transcripts were upregulated after elicitation. H2 O2 -treated roots showed higher levels of STR at 48-192 h and SGD at 24-48 h, while BSO-JA treatments showed STR increased at 12 h and SGD at 24 h. Also, LC/ESI-MS confirmed the biosynthesis of dolichantoside from N-ω-methyltryptamine and secologanin by U. tomentosa protein extracts.