Early habituation of maize (Zea mays) suspension-cultured cells to 2,6- diclorobenzonitrile is associated with the enhancement of antioxidant status

Abstract

The cellulose biosynthesis inhibitor 2,6-diclorobenzonitrile (DCB) has been widely used to gain insights into cell wall composition and architecture. Studies of changes occurring during incipient habituation to DCB can provide information on early cell mechanisms leading to cope with DCB-induced stress. In this context, maize cultured cells with a reduced amount of cellulose were obtained by stepwise habituation to low DCB concentrations. The results reported here attempt to elucidate the putative role of an antioxidant strategy during incipient habituation. The short-term exposure to DCB of non-habituated maize cultured cells induced a substantial increase in oxidative damage. Concomitantly, short-term treated cells presented an increase in class III peroxidase and glutathione S-transferase activities and total glutathione content. Maize cells habituated to 0.3 – 1 μM DCB (incipient habituation) were characterised by a reduction in the relative cell growth rate, an enhancement of ascorbate peroxidase and class III peroxidase activities, and a net increment in total glutathione content. Moreover, these cell lines showed increased levels of glutathione S-transferase activity. Changes in antioxidant/detoxifying status enabled 0.3 and 0.5 μM DCB-habituated cells to control lipid peroxidation levels, but this was not the case of maize cells habituated to 1 μM DCB, which despite showing an increased antioxidant capacity were not capable of reducing the oxidative damage to control levels. The results reported here confirm that exposure and incipient habituation of maize cells to DCB are associated with an enhancement in antioxidant/detoxifying activities which could play a role in incipient DCB habituation of maize cultured cells