Gawer, M., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France
Norberg, P., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France
Chervin, D., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France
Guern, N., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France
Mazliak, P., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France
Kader, J.-C., Lab. de Physiol. Cell. et Molec., U. CNRS 2135, Univ. Pierre Marie C., Paris, France

The biosynthesis of polyphosphoinositides was studied in cultured tobacco cells from Wisconsin 38 (W 38) and Bright yellow 2 (BY 2) lines. Following changes in the culture conditions the labelling with [14C] inositol or [33P] orthophosphate of the phosphoinositides and other phospholipids was largely affected. The labelling depended on the growth stage and was higher in the 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 labelling of the PI cycle metabolites whereas a cold stress preferentially stimulated PA and PIP labelling. In such cells, the limited change of PIP2 compared with the high level of labelled PIP and/or PA suggested a direct participation of these latter compounds to the signalling process in tobacco cells.