Efficient production and enhanced accumulation of Valerenic acid in Valeriana officinalis: Early identification of high-performing hairy root clones and Pioneering use of hydrogen peroxide as an elicitor

Abstract

Valeriana officinalis (valerian) roots and rhizomes possess a long history of medicinal use due to their sedative, antiepileptic, and anticonvulsant properties. Valerenic acid, a bioactive sesquiterpene with therapeutic potential, is present in limited quantities within these tissues. This study explores the application of hairy root cultures for enhanced valerenic acid production. Hairy root induction was attempted on valerian leaves and petioles using three Rhizobium rhizogenes strains (ATCC15834, A4, and MSU440) across three culture media (Murashige and Skoog (MS), Gamborg's B5 (B5), and Schenk and Hildebrandt (SH)). A non-destructive imaging system and periodic analyses were employed to identify superior hairy root clones exhibiting increased branching frequency. Leaf explants co-cultured with R. rhizogenes strain ATCC15834 yielded the most promising clones, characterized by the highest dry weight (1.03 mg) and valerenic acid content (0.384 mg/g dry weight) when grown in a half-strength SH liquid medium. Following strain and media optimization, the impact of 50 mM hydrogen peroxide as an elicitor on valerenic acid production was investigated. This treatment resulted in a significant 1.76-fold increase in valerenic acid accumulation compared to the control group at the first day post-treatment. This approach presents a valuable strategy for the early identification of high-yielding hairy root lines. Moreover, the utilization of hydrogen peroxide, a safe and cost-effective elicitor, offers a rapid method for enhancing valerenic acid production in the selected superior clone. This study establishes a promising platform for the sustainable production of valuable plant compounds within both research and industrial settings.