Woody plant medium enhances micropropagation of the medicinal shrub Blumea balsamifera (L.) DC.

Efficient micropropagation is essential for industrial use of Blumea balsamifera (L.) DC., the main natural source of L -borneol. This study compared basal medium composition and auxin regimes to improve in vitro propagation. Seven basal media (Murashige and Skoog MS, ½ MS, Woody Plant Medium WPM, WPM−, Linsmaier and Skoog LS, Gamborg’s B5, and Chu’s N6) were tested. Among the media tested, WPM gave the best overall performance. For shoot proliferation, WPM supplemented with 2.0 mg·L⁻¹ 6-benzyladenine and 1.4 mg·L⁻¹ indole-3-butyric acid produced the highest proliferation rate, reaching 7.9 shoots per explant. For root induction, WPM containing 0.3 mg·L⁻¹ 1-naphthaleneacetic acid produced the highest root number, with about 20 roots per explant. In addition, WPM supplemented with 0.3 mg·L⁻¹ NAA and 1.2 mg·L⁻¹ kinetin enabled a one-step culture protocol, allowing simultaneous shoot proliferation and rooting within a single culture cycle, thereby reducing the need for subculture. Compared with MS, WPM improved the proliferation rate, root number, root length, and plant height by 30%, 45%, 155%, and 99%, respectively. It also shortened the culture period and raised the acclimatization survival rate, facilitating plantlet establishment. Root transcriptome analysis of roots from plantlets cultured in WPM and MS indicated differential regulation of tryptophan metabolism and hormone signaling pathways, suggesting that enhanced root growth under WPM may be associated with hormone- and nitrogen-related transcriptional changes. These results establish WPM as an efficient and economical micropropagation system for B. balsamifera . • Woody Plant Medium outperformed MS for Blumea balsamifera micropropagation. • Proliferation rate, root number, and plant height increased 30%, 45%, and 99%. • Rooting time was shortened by 30%, and the acclimatisation survival rate improved. • Transcriptome revealed auxin and nitrogen regulatory shifts. • WPM-based one-step protocol enabled simultaneous shoot amplification and rooting.