Electrotherapy; a Promising Therapy to Eradicate Viruses from Infected in Vitro Olive Cv. Meshkat

Olive tree harbors several viruses affecting the yield and quality of fruit worldwide. Application of virus-free planting materials is one of the main strategies to counteract virus diseases. The elimination of Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Cucumber mosaic virus (CMV) and Strawberry latent ringspot virus (SLRSV) by different regimes of electrotherapy followed by 1 mm shoot tip culture was investigated in a native Iranian olive cultivar Meshkat. The results showed that survival, regrowth and proliferation rates were dependent on the therapy regime and shoot tip type. Apical shoot tips showed more significant proliferation rate compared to axillary ones under 30 min treatment of electric current. In addition, apical shoot tips represented higher survival and regrowth rate under 30 min of electrotherapy, 54 and 46% respectively compared to 15 min of therapy. Interestingly, the regrowth rate in the virus mixed-infected cv. Meshkat was notably increased by increasing the electrotherapy duration from 13 min to 10% to 40 min and 46% in axillary and apical shoot tips respectively. The traditional method of shoot tip culture has not been able to eradicate the viruses in question. However, ArMV, CLRV, CMV and SLRSV were completely eradicated by electrotherapy treatment (35 mA, 100 V, 30 min) and the therapy efficiency index (TEI) was 54 for all studied viruses. Moreover, electrotherapy treatment (35 mA, 100 V, 15 min) eradicated only ArMV (62.5%) and CLRV (50%) with TEI of 31.25 and 25 respectively. The results concluded that the combination of electrotherapy with shoot tip culture can be successfully used as a virus elimination method for producing virus-free olive plants.