Oxidative stress in recalcitrant tissue cultures of grapevine

Thiobarbituric acid reactive substances (TBARS), and fluorescent compounds 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 vinifera L. cultivar, Sultanina. These compounds increased during the early stages of dedifferentiation (callogenesis)of nodal stem explants. Catalase activity was not detected in the original explant, but was induced during callogenic dedifferentiation. Conversely, superoxide dismutase activity was detectable in the original explant, but diminished during the first week of callus induction. Transfer to callus induction medium promoted a large increase in the sulfhydryl content of nodal tissues. TBARS and fluorescent products accumulated in Sultanina callus during long-term culture (over 6 months). The possibility that oxidative stress may contribute to culture recalcitrance in this vine is discussed.