Abstract
We have reported that the overexpression of AtNUDX2, which have ADP-ribose pyrophosphatase activity, leads to the enhancement of oxidative stress tolerance in Arabidopsis. The free ADP-ribose is produced by the reverse process of poly(ADP-ribosyl)ation reaction and by the turnover of β-NAD. In this study, we analyzed the effect of ADP-ribose metabolism on oxidative stress in Arabidopsis. The transcript level of AtNUDX7, a homologue of AtNUDX2, was markedly induced under high light, drought, paraquat or high salinity. Similar results were observed in the levels of poly(ADP-ribose) polymerase and poly(ADP-ribose)glycohydrolase involved in the poly(ADP-ribosyl)ation reaction. The amounts of NAD+ and ATP in the transgenic plants overexpressing AtNUDX2 or 7 were decreased at much lower rate than those in the wild-type with the paraquat treatment. These results suggest that AtNUDX2 and 7 suppress the consumption of NAD+ and ATP by activation of poly(ADP-ribosyl)ation reaction under the stress conditions.
