Methyl jasmonate (JA-Me) applied to the abaxial side of the middle of leaf blade on the beginning of September extremely induced leaf senescence in Ginkgo biloba; three weeks after the treatment the leaves disappeared chlorophylls and became yellow, while the control leaves remained still green. Contrarily JA-Me applied to the adaxial side of leaves affected little to induce senescence. When JA-Me was treated on the abaxial side of a half of leaf blade across to the vein, the yellowing widely took place both in acropetal and basipetal directions along vein, but no yellowing was visible in the non-treated half. On the other hand, when JA-Me was applied to the abaxial side of a half of leaf blade along to the vein, yellowing was observed only in both sides of a small area along to the applied area, and little yellowing was visible in the neighboring lateral tissues. JA-Me treatment on the abaxial side of leaf blade greatly increased the levels of JA-Me and jasmonic acid in leaf blade and petiole. Endogenous abscisic acid levels substantially increased during natural and JA-Me-induced leaf senescence, but 1-aminocyclopropane carboxylic acid levels did not change. The contents of cytokinins, gibberellins and auxins identified changed little during natural and JA-Me-induced leaf senescence. These suggest that a cooperative crosstalk between JAs and various hormonal signals, especially abscisic acid, occurs in regulation of G. biloba leaf senescence. Possible different action of JA-Me applied to the abaxial and the adaxial sides of the leaves on leaf senescence is discussed.

中文翻译：

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茉莉酸甲酯诱导银杏叶片衰老：与植物激素内源水平的相关性

9月初在叶片中部背面施茉莉酸甲酯(JA-Me)极致银杏叶片衰老；处理三周后，叶子消失了叶绿素并变黄，而对照叶子仍然保持绿色。相反，将 JA-Me 应用于叶子的正轴侧几乎不会引起衰老。当JA-Me在叶脉的半叶背面进行处理时，沿叶脉的顶叶和基叶方向广泛发生黄化，但未处理的半叶未见黄化。另一方面，当将 JA-Me 沿叶脉施用于一半叶片的背面时，仅在沿施药区域的小区域两侧观察到变黄，并且在相邻的侧部组织中几乎不可见黄化。叶片背面的JA-Me处理大大增加了叶片和叶柄中JA-Me和茉莉酸的含量。在自然和 JA-Me 诱导的叶片衰老过程中，内源性脱落酸水平显着增加，但 1-氨基环丙烷羧酸水平没有变化。细胞分裂素、赤霉素和生长素的含量在自然和JA-Me诱导的叶片衰老过程中变化不大。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。叶片背面的JA-Me处理大大增加了叶片和叶柄中JA-Me和茉莉酸的含量。在自然和 JA-Me 诱导的叶片衰老过程中，内源性脱落酸水平显着增加，但 1-氨基环丙烷羧酸水平没有变化。细胞分裂素、赤霉素和生长素的含量在自然和JA-Me诱导的叶片衰老过程中变化不大。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。叶片背面的JA-Me处理大大增加了叶片和叶柄中JA-Me和茉莉酸的含量。在自然和 JA-Me 诱导的叶片衰老过程中，内源性脱落酸水平显着增加，但 1-氨基环丙烷羧酸水平没有变化。细胞分裂素、赤霉素和生长素的含量在自然和JA-Me诱导的叶片衰老过程中变化不大。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。在自然和 JA-Me 诱导的叶片衰老过程中，内源性脱落酸水平显着增加，但 1-氨基环丙烷羧酸水平没有变化。细胞分裂素、赤霉素和生长素的含量在自然和JA-Me诱导的叶片衰老过程中变化不大。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。在自然和 JA-Me 诱导的叶片衰老过程中，内源性脱落酸水平显着增加，但 1-氨基环丙烷羧酸水平没有变化。细胞分裂素、赤霉素和生长素的含量在自然和JA-Me诱导的叶片衰老过程中变化不大。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。这些表明 JA 和各种激素信号（尤其是脱落酸）之间的协同串扰发生在 G. biloba 叶片衰老的调节中。讨论了 JA-Me 应用于叶片背面和正面对叶片衰老可能产生的不同作用。