Articles
RECOVERY OF VIRUS-FREE ALMOND PLANTS BY SHOOT-TIP GRAFTING IN VITRO
It consists of aseptically grafting a 0.5–1.5 mm long shoot-tip from infected plants on 10 to 14-days-old Nemaguard peach seedlings grown in vitro. The grafted plants are grown for 4–6 weeks in vitro and then transplanted to the greenhouse.
A 40 to 50% incidence of grafting success and 75 to 85% of survival on transplanting were routinely obtained.
The influence of shoot tip size (0.5–0.9 mm and 1.0–1.5 mm) and the growing conditions of infected plants (under open air and growth chamber at 35°/30°C) on elimination of Prunus necrotic ringspot virus (PNRSV), Prune dwarf virus (PDV) and Apple mosaic virus (ApMV) was studied.
All plants recovered by STG were free of ApMV, regardless of shoot tip size or growing conditions of infected plants.
PNRSV and PDV could not be eliminated from plants growing in the open air but they were easily eliminated from plants growing in the growth chamber.
Shoot-tip size had no influence on elimination of PNRSV, and around 80% of the micrografted plants were free of this virus.
This parameter had a clear influence on elimination of PDV, since all plants regenerated from 0.5–0.9 mm long shoot-tips were healthy, whereas only 46% of plants regenerated from 1.0–1.5 mm long shoot-tips were free of PDV.