Studies Of Relationship Between Ca～(2+), CaM, Its Target Enzymes And Ethylene Inducing Maturation, Ripening And Senescence Of Tomato And Strawberry Fruits

Main physiological and biochemical parameters were studied in different mature stage and during ripening and senescence of tomato and strawberry fruits at pink stage after harvest under low and normal temperature .The results showed that during maturation, ripening and senescence of tomato, obvious changes took place in ethylene production, respiration, polygalacturonase(PG) activity , lycopene, chlorophyll and soluble protein in cell wall ; for strawberry ,there was no obvious changes in respiration and ethylene production but in activity oxygen metabolism, soluble protein content and composition. The features during maturation , ripening and senescence of tomato was different from strawberry.Ethylene induced the peak of respiration and ethylene production to emerge in advance, enhanced increase in PG activity , content of lycopene, and soluble protein in cell wall and degradation of chlorophyll in tomato fruit at green mature stage, which showed that ethylene is the most important factor starting and promoting maturation, ripening and senescence of tomato fruit. Ethylene had no affect on respiration, SOD activity , content of GVand H2O2 ,but could promote ethylene production rate, induce 34KD protein expression and enhance degradation of soluble protein in strawberry, which indicated that for strawberry, ethylene was not related to respiration and activity oxygen metabolism, but involved in regulation of maturation ,ripening and senescence through promoting ethylene autocatalysis, inducing special protein expression and enhancing degradation of soluble protein.When EGTA (Ca fehelalor),Verapmil and LaCl3 (Ca2+channcl blockers) were used to treat tomato fruit at green mature and strawberry fruit at while stage with ethylene, they could reverse ethylene-induced increase in ethylene production in tomato and strawberry, PG activity , lycopene content , soluble protein content in cell wall intomato and degradation in soluble protein in strawberry, which indicated blocking Ca2+channel in plasma membrane or chelaling Ca21 can decrease intracellular Ca2', further inhibite ethylene-induced maturation, ripening and senescence of fruit. The results indirectly indicated that influx of Ca2+ from the extracellular space including the cell wall via the Ca2+ channel localized in plasma membrane is required for ethylene-induced maturation, ripening and senescence of fruits and that ethylenc signal transduction may be related to Ca2+ messenger. Regulating intracellular Ca2+ concentration may influence ethylene-induced maturation, ripening and senescence of fruits.During maturation , ripening and senescence of tomato and strawberry fruits, calmodulin(CaM), a receptor protein of Ca2+, had similar changing trend, but the time when CaM peak appeared was different and related to storage life of fruit. CaM peak in strawberry fruit appeared earlier than in tomato fruit. Low temperature postponed emerging of CaM peak , indicating that the change of CaM content was associated with maturation , ripening and senescence of fruits. Ethylene increased CaM content in tomato and strawberry fruits, which was promoted by additional Ca2+ and inhibited by blocking Ca + channel or chelating extracellular Ca +. The results indicated that ethylene-inducd CaM accumulation was dependent on changing of cytoplasmic Ca2+concentration. The effect of ethylene on CaM was related to ethylene concentration. Trifluoperazine(TFP )and Chloropromaize(CPZ)are CaM antagonism. When they were used to treat tomato and strawberry fruit with ethylene, they inhibited ethylene-induced increase in respiration, PG activity ,lycopcne accumulation of tomato , ethylene production and degradation in soluble protein of strawberry, indicating that CaM involved in inducing of ethylene on major parameters related to maturation, ripening and senescence of tomato and strawberry fruits. Therefor , this paper proposed that Ca"f-CaM messenger system may involved in inducing of ethylene on maturation, ripening and senescence of climacteric fruit tomato and non-climacteric fruit...