Showing papers by "Shimon Mayak published in 1994"
TL;DR: The results of the present study suggest that in response to ethylene, activation of an existing enzyme is taking place first, followed by an increase in expression of ACC oxidase and ACC synthase mRNAs.
Abstract: The plant hormone ethylene triggers and enhanced ethylene synthesis in certain ripening fruits and senescing flowers. Unlike most carnation (Dianthus caryophyllus L.) cultivars exhibiting climacteric rise in ethylene production at the onset of senescence, cv. Sandrosa does not show this phenomenon naturally. In order to understand the mechanism of autocatalytic ethylene production, we exposed carnation flowers cv. Sandrosa to ethylene which resulted in an enhanced capacity for ethylene synthesis in the petals. A short time response of one hour was measured for an increase in ACC oxidase activity, about five hours in advance of an increase in ACC synthase activity and ethylene production. The observed enhancement was dependent on the presence of exogeneous ethylene, and could be partially inhibited by prior treatment of the petals with α-amanitin or cycloheximide. The results of the present study suggest that in response to ethylene, activation of an existing enzyme is taking place first. This is followed by an increase in expression of ACC oxidase and ACC synthase mRNAs.
27 citations
TL;DR: Western blot analyses of petal extracts after various exposure times to ethylene alone or in the presence of translation or transcription inhibitors suggested that accumulation of the 70-kDa protein is due primarily to ethene-induced synthesis, and data indicated that the protein is specifically expressed in carnation petals and not in petals of several other flowers.
Abstract: Ethylene enhances senescence of carnation (Dianthus caryophyllus L.) flowers. Sephacryl S-200 gel filtration followed by SDS-PAGE of extracts of petals exposed to ethyiene revealed the increase or appearance of proteins with molecular masses of 70, 60, 35 and 33 kDa, and a concomitant decrease in proteins with molecular masses of 62. 45. 34. 30 and 26 kDa.
The 70-kDa protein, which was not detected in untreated flowers, was isolated and polyclonal antibodies were prepared against it. Its N-terminal sequence (20 amino acids) was identical to that of a portion of the deduced protein encoded by cDNA clone pSR 12. recently isolated by others from carnation petals. Western blot analyses of petal extracts after various exposure times to ethylene alone or in the presence of translation or transcription inhibitors suggested that accumulation of the 70-kDa protein is due primarily to ethylene-induced synthesis. The apparent induction by ethyiene was further supported by data indicating that the protein is not formed in flowers pre-treated with silver thiosulfale. an inhibitor of ethylene action, prior to exposure to ethylene. Ethylene induction of the protein was found only in petal tissue, and the protein was not detected in other carnation plant organs. Immunological studies revealed that the protein is specifically expressed in carnation petals and not in petals of several other flowers. Southern and northern analyses using an SRI2 cDNA probe indicated that the genomic DNA of petunia, carnation, and gerbera contain fragments homologous to SRI2. Gene expression products were however, only detected in petals of ethylenetreated carnation flowers.
8 citations