ISHS Acta Horticulturae 179: V International Symposium on Growth Regulators in Fruit Production
MORPHACTIN-INDUCED INHIBITION OF ABCSISSION IN CITRUS LEAVES |
| Authors: | R. Goren, Y. Aron, S.P. Monselise, M. Huberman |
| Keywords: | cellulase, chlorflurecol-methylester, IAA transport, IAA-glucose, IAA-aspartate, polygalacturonase |
| Abstract:
Morphactin (chlorflurecol-methylester, 10-6M to 10-3M) inhibited polar auxin transport in midrib sections of citrus leaves, but not as a result of lack of free auxin in the absorbing apical segment of the midrib. Morphactin also induced the conjugation of IAA to aspartic acid (IAAsp) and glucose (IAAglu), and delayed abscission. However, at the level of 10-3M this delaying effect was much lower, probably due to the presence of ethylene which is induced by morphactin at this concentration. The stimulatory effect of ethylene on abscission was inhibited by morphactin during the first 10 to 16 hours after excision and exposure of leaves to ethylene. Morphactin also inhibited the activity of cellulase and polygalacturonase at the abscission zone. It is suggested that morphactin inhibits abscission by delaying the activity of cell-wall degrading enzymes, a mechanism which is not related to morphactin's inhibition of auxin transport to the abscission zone. | |
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