MEMBRANE LIPIDS INVOLVED IN THE REGULATION OF FLOWER SENESCENCE

Authors:	A. Borochov, H. Spiegelstein, R. Porat
Abstract: Flower senescence is accompanied by a decline in the content of membrane components, including nonspecific decreases in phospholipids. The aim of this work was to investigate the possible involvement of products of phospholipid metabolism in the regulation of petunia flower senescence. During the cut flower's development and senescence, a transient increase in the content of diacylglycerol (DAG) in the petal membranes was found, peaking towards wilting. Phorbol 12-myristate 13-acetate (PMA), a phorbol ester, is water-soluble and acts in various cellular metabolic processes, including kinase activation. PMA is an analog of DAG, and therefore serves as a useful tool for studying DAG's role in cell metabolism. Treating petunia flowers with 5 to 20 μM PMA enhanced wilting in a concentration-dependent manner. In addition, flower fresh weight and protein content declined earlier in PMA-treated flowers. The membrane lipid microviscosity of PMA-treated flowers increased faster than that of control flowers and the treatment induced an earlier ethylene production. Pre-treatment with STS nullified PMA's effects on flower senescence. Our results indicate a role for lipid metabolites in the regulation of flower senescence and support the possible role of kinase activity in this process.
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