Developing a system to produce uniform micropropagated horseradish (Armoracia rusticana) plants in vitro

Horseradish (Armoracia rusticana) production in Illinois is decreasing overtime. The cause of this decline seems to relate to how horseradish is propagated, typically asexually from root segments harvested from the previous year's crop. Using this practice, diseases can accumulate and be passed on year-to-year. To solve this problem we have suggested the development of a tissue culture (TC)-based system to produce disease-free mother plants that can be propagated asexually to provide growers with disease-free planting stock. The long-term goal of this project is to develop a certified program to deliver disease-free horseradish plants to growers. To initiate such a program, we have successfully developed TC-based methods to propagate five genetically diverse horseradish lines. To determine whether TC plants would be productive and true-to-type under field conditions, a sample of TC and root cutting-derived plants from five genetically diverse lines were field planted in 2003 and 2004 and evaluated for growth habits, root yields, virus infection, discoloration, peroxidase content and trueness-to-type under field conditions.; Overall, TC plants were found to be productive and gave larger root yields and less discoloration than root cutting-derived plants used in traditional propagation methods. The results are encouraging and have been presented to the Illinois Horseradish Growers Association (Shehata et al. 2004). Eventually these methods could provide an effective and alternative way for Illinois horseradish growers to produce better quality horseradish roots and regain their market share of the crop. The study is expected to help in the efforts toward eliminating horseradish diseases that is threatening the industry. It is considered the first step toward achieving our long term goal to develop a certified root program to deliver disease free horseradish plants to growers. We expect that achieving this goal could solve the current production disease problems, restore the yields, and help Illinois remain the leading state for horseradish production.