Uses dimethylallyl diphosphate and isopentenyl diphosphate to catalyze the cis-prenyl chain elongation and produce the 10 carbon product neryl diphosphate. dimethylallyl diphosphate + isopentenyl diphosphate = diphosphate + neryl diphosphate Expressed in leaf trichomes and stem trichomes. Belongs to the UPP synthetase family.