| Abstract: | Polygalacturonase (PG) was studied during ripening and senescence of postharvest tomatofruit at pink stage at low and normal temperature. The results showed that the PG activity increased, thendecreased during ripening and senescence of tomato. Low temperature inhibited but ethylene enhanced PGactivity. Ethylene also enhanced caimodulin content, which was dependent on Ca2+ concentration in cell.When EGTA(Ca2+ chelator), verapamil (Vp) and LaCl3 (Ca2+ channel blockers), trifluoperazine and chloro-promaize (two CaM antagonisms) were used to treat tomato fruit at green mature stage with ethylene, theycould reverse ethylene-induced increase in PG activity, but Vp, chloropromaize (CPZ), trifluoperazine(TFP) could not directly influence PG activity, which indirectly indicated that influx of Ca2+ from the ex-tracellular space including the cell wall via the Ca2+ channel localized in plasma membrane and CaM were re-quired for ethylene-induced PG activity increase and that ethylene signal transduction may be related to Ca2+- CaM messenger system. |
