THE CHANGES IN FATTY ACID PROFILE DURING SENESCENCE AND METHYL JASMONATE-INDUCED SENESCENCE OF Ginkgo biloba LEAVES

The present study describes changes in fatty acid (FA) composition in Ginkgo biloba leaves subjected to senescence and to senescence induced by methyl jasmonate (MeJA). Green leaves were treated with MeJA in lanoline on the abaxial or adaxial side of the leaf blades. After three weeks of treatment, leaf blades and petioles were collected separately for FA analyses. Additionally, petioles and leaf blades were sampled for analyses before the experiment and after 6 weeks when leaf senescence was occurring. Linolenic (C18:3) and palmitic (C16:0) acids appeared to be the quantitatively most abundant FA in leaf blades and petioles of G. biloba. Both leaf senescence and that induced by MeJA caused a decrease in unsaturated FA content, especially linolenic (C18:3). However, the decrease in C18:3 acid in both leaf blades and petioles was greater when MeJA was applied to the abaxial side than when it was applied to the adaxial side of leaves or during senescence. At the same time, saturated FA content increased, resulting in a significant decrease in the ratio of total unsaturated to saturated FA. Since leaf fatty acids occur mainly as components of cell membranes, changes in their composition may have a crucial effect on membrane function and stability, as pointed out in the discussion of the results.