CORRELATION OF POTATO-VIRUS-S AND POTATO-VIRUS-M CONTENTS OF POTATO MERISTEM TIPS WITH THE PERCENTAGE OF VIRUS-FREE PLANTLETS PRODUCED IN-VITRO

Using sensitive Dot-ELISA, potato virus 8 (PVS) and potato virus M (PV M) contents per single potato meristem tip of 4-leaf primordia were de termined, and were correlated with the percentage of virus-free plantl ets obtained by meristem-tip culture preceded by chemo- and thermother apy of the plants. Treatment of PVS-infected cv. Majestic plants for 2 6 days at 35 degrees C resulted in 85% of the meristems having less th an 10 pg of virus, and 89% of the derived progenies were similarly vir us-free. When stem cuttings were dipped for 15 days in various chemica ls, the mixture of 5 mg/l ribavirin + 5 mg/l DHT was the most effectiv e. For cvs Majestic and Primura, 90 and 72% of the meristems had less than 10 pg of virus, and resulted in 74 and 67% virus-free progenies r espectively. In PVM infection of the two cultivars, the same mixture y ielded 70 and 66% meristems with less than 10 pg of virus, and 69 and 68% virus-free progenies.