elimination of grapevine virus a (gva) by cryotherapy and electrotherapy

the incidence of grapevine virus a (gva) is reported from almost all of the major grapevine growing regions in iran. grapevine is vegetatively propagated by rooting of cuttings or grafting. in such plants, viral diseases are transmitted from stock plants to the progeny. therefore, the control of grapevine viruses can be achieved primarily through production of healthy stock plants. in the present research, cryotherapy and electrotherapy were employed for elimination of gva from naturally infected vine (vitis vinifera l. cv black) and their efficiency was compared. in cryotherapy, 59% of the shoot tips survived and regenerated into whole plants, of which 42% were free of gva detected by rt-pcr. in the electrotherapy, the effects of electric current value and treatment duration were investigated on plant survival and virus elimination. the best results were obtained by using 30 milliamps (ma) for 15 minutes. with this treatment, survival and virus-free frequencies were about 62% and 40%, respectively. this is the first report of electrotherapy of grapevine shoot tips as a potential tool for gva elimination. the results showed that cryotherapy was a more efficient and convenient protocol than electrotherapy for elimination of gva from infected grapevine.