Is jasmonic acid involved in the endogenous regulation of Dendrobium orchid flower senescence?
1995
Porat, R. | Borochov, A. | Halevy, A.H.
Jasmonic acid (JA) and its methyl ester (JA-Me) are naturally occurring plant compounds that have been reported to accelerate senescence in several plant tissues. JA biosynthesis involves cleavage of linoleic acid from membrane phospholipids and oxidation by lipoxygenase (LOX). Exogenous application of JA-Me to Dendrobium orchid flowers accelerated their senescence and induced an increase in ethylene production and in 1-aminocyclopropane-1-carboxylic acid (ACC) content. The effects of JA-Me on Dendrobium flower senescence were similar to that of pollination. To study the possible involvement of JA in the endogenous regulation of Dendrobium flower senescence, we examined the effects of JA biosynthesis inhibitors, the activity of LOX and the accumulation of jasmonates following pollination of Dendrobium flowers. We found that treating flowers with the LOX inhibitors salicylhydroxamic acid (SHAM) and n-propyl gallate (n-PG) had no effect on the pollination-induced senescence of the flowers. Furthermore, during the 50-h period from pollination to the completion of wilting, there was no increase in LOX activity. During the 10-h period from pollination to the initiation of ethylene production there was no change in jasmonate levels. These results indicate that although exogenous application of JA-Me enhances ethylene production and Dendrobium flower senescence, LOX activity and jasmonates are probably not involved in the endogenous regulation of this process.
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