ULTRASTRUCTURAL-CHANGES PRODUCED IN PLANTLET LEAVES AND PROTOPLASTS OF VITIS-VINIFERA CV CABERNET-SAUVIGNON BY EUTYPINE, A TOXIN FROM EUTYPA-LATA

Eutypine is a toxin produced by Eutypa lata (Pers.: Pr.) Tul., the cau sal agent of dying-arm disease of the grapevine. Ultrastructural alter ations induced by eutypine in leaf cells and protoplasts isolated from plantlets of Vitis vinifera cv. Cabernet Sauvignon, a very sensitive variety cultured in vitro, were observed for the first time by transmi ssion electron microscopy. Eutypine caused early cytoplasm lysis and v esiculation followed by chloroplast swelling with thylakoid dilation. The eutypine-induced alterations of the cellular ultrastructure are si milar to those previously described in vivo in the leaves of diseased grapevines. These results confirm that eutypine, synthesized by E. lat a mycelium present in the trunk or arms, is involved in symptom expres sion of eutypiosis in the herbaceous parts of grapevine.