Production of Viroid-Free Grapevines by Shoot Tip Culture

Abstract

Viroids have been shown to be widespread in all rootstocks and varieties tested. Evaluation of the effect of viroids on the growth and productivity of grapevines, as well as on grape quality, relies on the availability of viroid-free grapevines. Grapevine shoot tips (0.1 - 0.2 mm in length) from a viroid-infected plant containing one or two leaf primordia were cultured <i>in vitro</i>. They developed into multiple-shoot cultures. The shoots were easily rooted into whole plantlets that were successfully transplanted to soil. Analysis by nucleic acid extraction and sequential polyacrylamide gel electrophoresis showed that all shoot tip recovered plants were viroid-free, in contrast with the mother plant which contained two viroid-like RNAs. The micropropagation system, also described, ensures the availability of large numbers of viroid-free grapevines when needed.