Abraham H. Halevy

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Pollination initiates a syndrome of developmental events that contribute to successful reproduction, including perianth senescence, changes in pigmentation, and ovule differentiation in preparation for impending fertilization. In orchid flowers, initiation of each of these processes in distinct floral organs is strictly and coordinately controlled by(More)
The possible involvement of Ca2+ as a second messenger in snapdragon (Antirrhinum majus L.) shoot gravitropism, as well as the role of ethylene in this bending response, were analyzed in terms of stem curvature and gravity-induced asymmetric ethylene production rates, ethylene-related metabolites, and invertase activity across the stem. Application of Ca2+(More)
Medium type, its water status and the relative humidity in the culture vessel modified carnation leaf development in vitro. Carnation shoot apices cultured on liquid or on 0.8% agar solidified media developed into plantlets having succulent and translucent leaves which are not transplantable to non-aseptic conditions. Increasing the agar and/or sucrose(More)
Removal of stamens, or even of only the anthers, at an early stage of corolla development, before the start of main anthocyanin production, inhibited both growth and pigmentation of attached corollas of Petunia. When only one or two stamens were removed from one side, the inhibition was restricted to the corolla side adjacent to the detached stamens.(More)
The application of Ethrel (2-chloroethane phosphonic acid), an ethylene-releasing compound, to monoecious cultivars of cucumber and squash and an andromonoecious cultivar of muskmelon, caused a shift towards femaleness in all three species. The increase in femaleness manifested itself in several symptoms: a decrease in the number of staminate (male)(More)
Ethylene evolved from monoecious and gynoecious cucumber (Cucumis sativus) plants grown under short and long day conditions was determined. More ethylene was evolved from floral buds and apices bearing buds than from whole seedlings of comparable weight. More ethylene also was evolved from apices of the gynoecious than from those of the monoecious type.(More)
The putative Ca(2+)-channel blocker LaCl3 prevented the gravitropic bending of cut snapdragon (Antirrhinum majus L.) spikes (S. Philosoph-Hadas, S. Meir, I. Rosenberger, A.H. Halevy [1996] Plant Physiol 110: 301-310) and inhibited stem curvature to a greater extent than vertical and horizontal stem elongation at the bending zone. This might indicate that(More)
EGTA, a specific Ca(2+) chelator, inhibited the flowering response of Pharbitis nil when applied to the cotyledons immediately before the inductive dark period. Calcium sprayed 30 minutes after the EGTA blocked the effect of EGTA. The length of the critical dark period was increased both by EGTA and by LaCl(3). The calmodulin antagonists W-7 and(More)
Pink Petuniahybrida (cv Hit Parade Rosa) corollas were found to contain photosynthetically active chloroplasts. The corolla chloroplasts were similar to those of green leaves in size and structure. The chlorophyll (Chl) content of Petunia corollas increased during early stages of flower development, reaching a maximum just before anthesis. Chloroplasts(More)
Pretreatment of detached carnation petals (Dianthus caryophyllus cv White Sim) for 24 hours with 0.1 millimolar of the cytokinins n(6)-benzyl-adenine (BA), kinetin, and zeatin blocked the conversion of externally supplied 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene and delayed petal senescence by 8 days. The normal enhanced wilting and increase(More)