ELIMINATION OF GRAPEVINE LEAFROLLASSOCIATED VIRUS 1 AND GRAPEVINE RUPESTRIS STEM PITTINGASSOCIATED VIRUS FROM GRAPEVINE cv AGIORGITIKO AND A MICROPROPAGATION PROTOCOL FOR MASS PRODUCTION OF VIRUSFREE PLANTLETS
F.G. Skiada, K. Grigoriadou, V.I. Maliogka, N.I. Katis , E.P. Eleftheriou
Grapevine leafroll-associated virus 1 (GLRaV-1) and Grapevine rupestris stem pitting-associated virus (GRSPaV) were eradicated from Vitis vinifera L. cv. Agiorgitiko by combining in vitro thermotherapy and tissue culture. GRSPaV is known to be quite recalcitrant to elimination, whereas GLRaV-1 is more easily knocked out. In this study, the effectiveness of two different virus elimination techniques, including meristem- and shoot-tip culture, was evaluated. Results showed that meristem-tip culture combined with thermotherapy was the most effective for eliminating both viruses as confirmed by nested RT-PCR assays. Success rate for GLRaV-1 (91.2%) was higher than for GRSPaV-1 (67.6%). The ratio of virus elimination to survival was higher for meristem-tip culture than for shoot tips (1.108 and 0.469 respectively). The effect of six basal media on in vitro shoot proliferation of virus-free explants of cv. Agiorgitiko was also studied and woody plant medium (WPM) proved to be the most effective. The presence of cytokinin 6-benzyladenine (BA) alone resulted in chlorotic plantlets, while supplementation with the auxin naphthaleneacetic acid (NAA) enhanced proliferation rate. Root induction at two temperature regimes (22±2°C and 26±2oC) revealed that higher temperature was more effective in the presence of IBA (indole-3-butyric acid) rather than NAA.