Micropropagation of Black Cohosh

Black cohosh (Actaea racemose) is considered one of the top selling herbs in the United States. Its popularity is developing into a problem because it is normally a slow-growing perennial that takes up to 4-6 years to mature and provide plant parts for medicinal uses. The over collection of this species has caused habitat destruction for this species thus leading to becoming an endangered species. Production with true black cohosh seeds is unreliable because the seeds must be stratified and usually germinate over a period of two years after sowing. Therefore, this research was initiated to develop a micropropagation protocol with a goal of significantly increasing production of this highly demanded medicinal plant. Tender leaves of black cohosh plants grown in a campus greenhouse were used as explant materials. Following a standard surface disinfestation procedure, the leaves were cut into one square centimeter pieces and cultured on Murashige and Skoog base medium supplemented with different plant growth regulators (TDZ, BA, kinetin, IBA, and NAA). The cultures were incubated in a plant growth chamber at 23^oC under 16 hours of light per day. After eight weeks of culturing, leaf explants from the BA, TDZ and kinetin treatments produced plantlet clusters. Those plantlet clusters were subsequently rooted in vitro in a medium containing IBA or NAA. Rooted plantlets were then acclimatized and are currently growing showing normal morphology as the stock plants from which they were cultivated in the same greenhouse.