Long-term response on growth, antioxidant enzymes, and secondary metabolites in salicylic acid pre-treated Uncaria tomentosa microplants.

Abstract

To obtain micro propagated Uncaria tomentosa plantlets with enhanced secondary metabolites production, long-term responses to salicylic acid (SA) pre-treatments at 1 and 100µM were evaluated after propagation of the plantlets in a SA-free medium. 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 100µM 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 1µM SA. Also, both pre-treatments increased total monoterpenoid oxindole alkaloids by ca. 55% (16.5mgg(-1) DW), including isopteropodine, speciophylline, mitraphylline, isomitraphylline, rhynchopylline, and isorhynchopylline; and flavonoids by ca. 21% (914μgg(-1) DW), whereas phenolic compounds were increased 80% (599μgg(-1) DW) at 1µM and 8.2% (359μgg(-1) DW) at 100µM SA. Pre-treatment with 1µM 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.