Phosphoinositides and stress-induced changes in lipid metabolism of tobacco cells

The biosynthesis of polyphosphoinositides was studied in cultured tobacco c ells from Wisconsin 38 (W 38) and Bright yellow 2 (BY 2) lines. Following c hanges in the culture conditions the labelling with [14C] inositol or [33P] orthophosphate of the phosphoinositides and other phospholipids was largel y affected. The labelling depended on the growth stage and was higher in th e actively growing BY 2 cells than in W 38 cells. Addition of hormones such as 2,4-D or abscisic acid (ABA) resulted in transient changes in the label ling of the PI cycle metabolites whereas a cold stress preferentially stimu lated PA and PIP labelling, In such cells, the limited change of PIP2 compa red with the high level of labelled PIP and/or PA suggested a direct partic ipation of these latter compounds to the signalling process in tobacco cell s. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.