Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, LE12 5RD, Loughborough, UK.
Planta. 1983 Mar;157(2):174-9. doi: 10.1007/BF00393652.
A critical role in the initiation of ripening has been proposed for pectolytic enzymes which are known to be involved in fruit softening. The hypothesis that tomato (Lycopersicon esculentum Mill.) ripening is controlled by the initial synthesis of the cell-wall-degrading enzyme polygalacturonase (EC 3.2.1.15), which subsequently liberates cell-wall-bound enzymes responsible for the initiation of ethylene synthesis and other ripening events, has been examined. A study of kinetics of ethylene evolution and polygalacturonase synthesis by individual fruits in a ripening series, employing an immunological method and protein purification to identify and measure polygalacturonase synthesis, showed that ethylene evolution preceded polygalacturonase synthesis by 20h. Exogenous ethylene stimulated the synthesis of polygalacturonase and other ripening events, when applied to mature green fruit, whereas the maintenance of fruits in a low ethylene environment delayed ripening and polygalacturonase synthesis. It is concluded that enhanced natural ethylene synthesis occurs prior to polygalacturonase production and that ethylene is responsible for triggering polygalacturonase synthesis indirectly. Possible mechanisms for ethylene action are discussed.
已有人提出果胶酶在成熟启动中起着关键作用，众所周知，果胶酶参与了果实软化。人们曾假设番茄（Lycopersicon esculentum Mill.）的成熟受细胞壁降解酶聚半乳糖醛酸酶（EC 3.2.1.15）的初始合成控制，该酶随后释放出负责引发乙烯合成和其他成熟事件的细胞壁结合酶。通过对成熟系列中单果的乙烯释放动力学和聚半乳糖醛酸酶合成的研究，采用免疫学方法和蛋白质纯化来鉴定和测量聚半乳糖醛酸酶合成，结果表明乙烯释放比聚半乳糖醛酸酶合成早 20 小时。当外源性乙烯应用于成熟的绿果时，它会刺激聚半乳糖醛酸酶和其他成熟事件的合成，而将果实保持在低乙烯环境中会延迟成熟和聚半乳糖醛酸酶合成。因此可以得出结论，增强的天然乙烯合成发生在聚半乳糖醛酸酶产生之前，并且乙烯通过间接作用触发聚半乳糖醛酸酶合成。还讨论了乙烯作用的可能机制。
