Jasmonates are key factors inducing exudation of gum polysaccharides : Mode of action of jasmonates focusing on ethylene interaction

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The purpose of this study was to know the mechanism of jasmonates(JAs) to induce gum formation in various plants especially in stone-fruit trees and tulips.(1)Exogenous application of jasmonates to various plant species in Rosaceae such as peach, apricot, sour cherry and plum induced gum formation. Exogenous applied ethylene (ethephon : ethylene-generating compound, Eth) also induced gum formation in these plant species. Simultaneous application of JAs and Eth showed synergistic effect on gum formation, suggesting that in stone-fruit trees JAs and Eth regulate gum formation by interacting with each other. An inhibitor of JA reduced Eth-induced gum formation in plum fruits, while that of Eth did not affect JA-induced one. The application of JAs to plum fruits s enhanced Eth production, while that of Eth did not increase endogenous level of JAs. These suggest that in stone-fruit trees, JAs play an important role in inducing gum formation by interacting with Eth.(2)In tulips (Tulipa gesne … More riana L.cv.Apeldoorn), based on the procedure to detect the endogenous factors inducing gum, jasmonic acid(JA) and methyl jasmonate (JA-Me) were successfully identified using a GC-MS. Total amounts of JAs (JA+JA-Me) in tulip stems were estimated with deuterium labeled ones as internal standards, being about 70 to 80 ng/g Fw. The application of JA and JA-Me substantially induced gums with Eth production. The application of Eth, however, induced no gummosis although it only slightly affected content of JAs in tulip stems. These results suggest that JAs are endogenous factors to induce gummosis in tulips. JAs stimulated Eth production, but application of ethylene had no effect on endogenous levels of JAs. JAs strongly decreased the total amount of soluble sugars in tulip, but Ethn did not, while both JA-Me and Eth stimulated senescence of the shoot shown by the loss of chlorophyll. These results suggest that gum formation induced by the application of JAs in tulip shoots is connected with the sugar metabolism. The mode of action of jasmonates in gummosis of tulip shoots will be discussed in relation to Eth production, sugar metabolism and senescence. Less