The changes of calmodulin (CAM) content in tomato (Lycpersicon esculentum Mill Dahong) fruits during ripening and senescence were determined by enzyme linked immunosorbent assay (ELISA). It was found that from the onset of climacteric the CaM content increased and reached the maximmum at the full ripe stage (P), then decreased during senescence. Corresponding to the changes of CaM content, the ACC content, the activity of ACC synthase and the internal ethylene concentiation (IEC) also increased with the cli...