A. De Marco et Ka. Roubelakis-angelakis, Specific features of the ascorbate/glutathione cycle in cultured protoplasts, PL CELL REP, 18(5), 1999, pp. 406-411
Protoplasts: isolated from Nicotiana ln tabacum ( L.) leaves were cultured
for 6 days in liquid medium and some features of their antioxidant capacity
were investigated. Ascorbate exported into the culture medium was oxidized
non-enzymically, whereas important modifications of the enzymic scavenging
activity were detected inside protoplasts. A new pool of isoenzymes, most
of them with cytoplasmic characteristics, ensures the increased ascorbate p
eroxidase activity. The specific activity of other enzymes involved in the
ascorbate/glutathione cycle, such as dehydroascorbate reductase and glutath
ione reductase, and of glutathione peroxidase were modified, resulting in c
ultured protoplasts with quantitative differences in antioxidant capacity c
ompared to leaves. The hypothesis presented here suggests that the new scav
enging system is related to differences in the compartment-specific accumul
ation of active oxygen species following protoplast isolation.