菠萝果实发育过程中有机酸含量及相关代谢酶活性的变化

以菠萝品种卡因为试验材料,测定了不同发育时期果实中有机酸含量及其有机酸代谢相关酶—磷酸烯醇式丙酮酸羧化酶(PEPC)、柠檬酸合成酶(CS)的活性变化,并对果实中酸积累与酶活性的关系进行了分析。结果表明,卡因菠萝果实中所含有机酸有柠檬酸、苹果酸、酒石酸、乙酸、草酸、马来酸,其中主要有机酸为柠檬酸(约占62%)、其次为苹果酸(约占14%)、酒石酸、乙酸和草酸的含量较低,马来酸微量。随着果实的发育,柠檬酸含量呈低-高-低的变化趋势,苹果酸、草酸、乙酸、酒石酸含量均呈下降趋势,柠檬酸在果实成熟时占主要优势,是果实主要的有机酸。在幼果期到果实迅速生长后期(花后10～70d),柠檬酸合成酶(CS)和磷酸烯醇式丙酮酸羧化酶(PEPC)活性与柠檬酸含量呈显著正相关。进入果实青熟期(花后90d)后,果实柠檬酸含量变化与PEPC和CS活性并无明显联系,此期酸积累不仅仅依赖这些酶的活性水平,还与其他因素有关。

Changes in organic acid concentrations and the relative enzyme activities during the development of Cayenne pineapple fruit

The contents of organic acids and the activities of organic acid-metabolizing enzymes,including phosphoenolpyuvate carboxylase(PEPC)and citrate synthetase(CS)were studied and their correlations were analyzed during the fruit development of pineapple cv. Cayenne. The results showed that there were citric acid,malic acid,tartaric acid,acetic acid,oxalic acid and maleate in fresh Cayenne fruit .The dominant organic acids in ripe fruit were critic acid (62%) and malic acid (14%).Concentration of citric acid gradually increased during fruit development and peaked 20 days before harvest and then declined slightly,while the other acids declined gradually. Correlation analyses showed that there was an significant positive correlation between the content of citric acid and the activities of CS and PEPC at the first and second stage of fruit development (10 to 70 d after anthesis). The activities of PEPC and CS showed no significant correlation to the changes in citric acid after the green maturing stage,indicating that acid accumulation might also involve actions of other factors.