OXIDATIVE STRESS IN RECALCITRANT TISSUE-CULTURES OF GRAPEVINE

Thiobarbituric acid reactive substances (TBARS), and fluorescent compo unds with spectral characteristics typical of products associated with oxidative stress in senescent and aging plant and animal cells, were detected in tissue cultures of the recalcitrant grapevine Vitis vinife ra L. cultivar, Sultanina. These compounds increased during the early stages of dedifferentiation (callogenesis) of nodal stem explants. Cat alase activity was not detected in the original explant, but was induc ed during callogenic dedifferentiation. Conversely, superoxide dismuta se activity was detectable in the original explant, but diminished dur ing the first week of callus induction. Transfer to callus induction m edium promoted a large increase in the sulfhydryl content of nodal tis sues. TBARS and fluorescent products accumulated in Sultanina callus d uring long-term culture (over 6 months). The possibility that oxidativ e stress may contribute to culture recalcitrance in this vine is discu ssed.