Improvement of growth and bacoside production in Bacopa monnieri through induced autotetraploidy with colchicine

Bacopa monnieri is a medicinal herb that is increasing in demand in Thailand. However, the lack of high-bacoside cultivars has limited pharmaceutical utilization and production. Here, chromosome doubling in B. monnieri was attempt to improve biomass and bacoside content in its seedling. Nodal segments were treated with colchicine (0, 0.025, 0.05, 0.075, 0.1, and 0.5% w/v) for 24 or 48 h before transferring to multiple shoot induction medium (1/2 MS medium supplemented with 0.2 mg L-1 BAP). Of 326 tested clones, 18 and 84 were mixoploids and autotetraploids, respectively. The highest autotetraploid-induction percentage (14.6%) was found after treated with 0.5% (w/v) colchicine, and 48 hours exposure. From 28 selected autotetraploid clones, 21 and 13 have significantly higher fresh and dry weight compared to the diploid clone, respectively. The maximum fresh and dry weight of autotetraploid plants was 2.8 and 2.0-time higher than diploid plants, respectively. Moreover, the maximum total bacoside content (1.55 mg plant(-1)) was obtained from an autotetraploid plant, which was 2.3-fold higher than the level in diploid plants. These novel autotetraploids have the potential to be developed as resources for value-added improvements in the medicinal and pharmaceutical industries.