AN IN-VITRO PROCEDURE TO ERADICATE POTATO-VIRUS-X, POTATO-VIRUS-Y, AND POTATO-VIRUS-S FROM RUSSET NORKOTAH AND 2 OF ITS STRAINS

A tissue culture method was developed for the eradication of three imp ortant potato viruses, PVX, PVY, and PVS, from the Russet Norkotah var iety and two of its strains (TXNS 112 and TXNS 278). The method combin ed the use of liquid medium, thermotherapy, and chemotherapy. Initiall y, virus-free plants were inoculated with PVX, PW, and PVS and, after 10 d, tested quantitatively for virus titer by ELISA to determine the initial virus concentration. The apical tip and the roots were removed from the inoculated plants, and only stem sections from inoculated pl ants were cultured in liquid medium containing MS inorganic salts, vit amins, and ribavirin (40 mu M or 80 mu M) After 5 d, half of the plant s were subjected to thermotherapy and half were kept at room temperatu re. At 6 wk, the uppermost node (5-7 mm) was removed and recultured, a nd plants were tested then and again after 6 wk using ELISA to identif y the virus-free plants. Ribavirin alone eradicated the viruses from s ome plants; however, more virus-free plants were obtained when the tre atments included heat. Additionally, the in vitro culture technique us ing liquid medium promoted rapid lateral shoot elongation and resulted in significantly faster plant production. Also this approach, which r equired less skilled labor, produced more plants than the meristem cul ture method for virus eradication. A detailed procedure for eliminatio n of multiple viruses is described. This procedure resulted in product ion of more than 10% virus-free plants.