Electrophysiological study on ethylene induction in fruit and vegetables.

以黄瓜（Cucumis sativus L.）果实为研究对象，对直流电对乙烯生物合成的影响进行了电生理研究。1) 1 ~ 3mA直流电诱导乙烯合成，1h时出现尖峰。这种突然的乙烯合成诱导伴随着1-氨基环丙烷-1-羧酸（ACC）合成酶和ACC氧化酶的同样突然的激活。2)从黄瓜果实中获得了至少6种不同的ACC合酶cdna。通过northern印迹法，在黄瓜果实中直流电表达了5种ACC合成酶mrna。3)对黄瓜果实组织特性进行电阻抗分析，了解阻抗组分与直流电诱导下乙烯生物合成的关系。阻抗由五个分量计算；电容代表质膜和细胞器膜，电阻代表细胞外空间、细胞质和细胞器内部。直流电为3 mA时，细胞器膜的电容、胞外间隙和细胞质的电阻均急剧增加。乙烯作用抑制剂二氮环戊二烯消除了直流电诱导的胞外空间电阻，但对细胞器膜电容的增加和细胞质电阻没有影响。结果表明，外部施加电流可能通过改变细胞器膜和/或细胞质pH的功能产生信号来诱导ACC合酶。

Electrophysiological studies on ethylene biosynthesis was conducted with application of direct current to cucumber (Cucumis sativus L.) fruit.1) Direct current of 1 to 3mA induced ethylene synthesis with a sharp peak at 1h. This abrupt induction of ethylene synthesis was accompained by an equally abrupt activations of 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase.2) At least six different cDNAs for ACC synthase were obtained from cucumber fruit. By northerm blotting, five ACC synthase mRNAs were expressed withdirect current in cucumber fruit.3) Electrical impedance analysis of tissue properties was conducted in order to understand the relationship between impedance components and ethylene biosynthesis induced by direct current in cucumber fruit.Impedances were calculated from five components ; capacitances representing plasma membrane and organelle membranes, and resistances representing extracellular space, cytoplasm, and organelle interior. With direct current of 3 mA,capacitance of organelle membranes and resistances of extracellular space and cytoplasm were increased abruptly.Diazocyclopentadiene, an inhibitor of ethylene action, eliminated the direct current induction of resistance of extracellular space, but no effect on the increase in capacitance of organelle membranes and resistance of cytoplasm. The results indicate that an extemally applied current may generate signal (s) by altering the functions of organelle membranes and/or cytoplasmic pH to induce ACC synthase.