ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
THE USE OF IN VITRO THERMOTHERAPY TO OBTAIN TURNIP MOSAIC VIRUS-FREE HORSERADISH PLANTS |
| Authors: | M. Uchanski, R.M. Skirvin, M.A. Norton |
| Keywords: | Armoracia rusticana, meristemming, tissue culture, root quality, discoloration, disease elimination |
| Abstract:
Illinois is the leading producer of horseradish (Armoracia rusticana) and horseradish products in the United States. The overall quality and yield of Illinois horseradish roots has declined significantly within the past few years and is believed to be related to the build up of soil- and insect-borne diseases including viruses. The most detrimental virus is thought to be Turnip Mosaic Virus (TuMV). To free horseradish plants of TuMV four horseradish cultivars (9705, 9769, 7586 and Doll) growing in vitro were subjected to two different temperature treatments: 37°C for 7, 9, 11, 14, 16, 18, 21, 23 or 25 days and 40°C for 7, 8, 9, 10, 11 or 12 days. At each of these intervals, apical meristem explants, small enough to be free of leaf primordia (ca. ½ mm in length), were excised and grown in vitro. To screen for the presence of TuMV, the meristem-derived plants were assayed using RNA reverse transcriptase and polymerase chain reaction (RT-PCR). A primer specific to a conserved sequence in the TuMV coat protein was used to produce bands which were visualized using agarose gel electrophoresis. PCR results were then compared with traditional enzyme-linked-immuno-sorbant assay (ELISA) tests. All cultivars treated at 37°C for up to 23 days produced viable meristems that grew to become whole plants. At 40°C, only one cultivar (Doll) yielded a viable meristem. Both the controls, which received no special heat treatments, and the four thermotherapy-treated plants were found to be virus-free suggesting that meristemming alone may be sufficient to make virus-free plants. The results of ELISA and PCR tests were in agreement, but we feel that PCR tests are more accurate because they could distinguish between plants with low viral loads and those that are totally virus-free. | |
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