Attempts to eliminate phytoplasmas from grapevine clones by tissue culture techniques

Individual lines of Vitis vinifera Barbera and Chardonnay were obtained by in vitro culture of axillary buds collected from phytoplasma-affected mother plants. The molecular assays did not detect the "flavescence doree" (FD) phytoplasma in the 66 lines tested after 6-9 months of culture, while the "bois noir"-associated phytoplasma was detected in 22 out of 50 lines. Despite the observed inefficiency of the FD phytoplasma in infecting micropropagated grapevine plants, additional strategies for phytoplasma elimination are advisable. Preliminary assays on the sensitivity of grapevine explants to oxytetracycline showed that axillary bud cultures were severely damaged by 100 mg(.)1(-1) oxytetracycline in the culture medium, while 50 mg(.)1(-1) did not inhibit the growth of plantlets with young roots.