Enhanced efficiency of virus eradication following thermotherapy of shoot-tip cultures of pear

In this study, in vitro-cultured plants of Pyrus pyrifolia cv. Fengshui, widely grown in central and southern China, were treated at different temperatures, and the efficiency of virus eradication of regenerated plants was evaluated by ELISA and dot-blot hybridization. Results showed that treatment at a constant high temperature of 37A degrees C influenced greatly on the growth of in vitro pear plants and significantly decreased the plant survival rate, though virus-free plants could be regenerated from a few survived plant tips. When the treatment was carried out at 32A degrees C/night and 38A degrees C/day, the survival rate and growth of pear plants could be significant improved, but no virus-free plants could be regenerated from shoot tips treated for 50 days. Based on these results, infected plants were heat-treated at 42A degrees C/day and 34A degrees C/night. High virus eradication efficiency was achieved from treated cultures of pear for more than 55 days. Results also verified that ACLSV could be eliminated from pear by 5 days shorter treatment period than that for ASGV and ASPV eradication.