Y. Mor

Changes in 1-aminocyclopropane-1-carboxylic-acid content of cut carnation flowers in relation to their senescence

The rise in ethylene production accompanying the respiration climacteric and senescence of cut carnation flowers (Dianthus caryophyllus L. cv. White Sim) was associated with a 30-fold increase in the concentration of 1-aminocyclopropane-1-carboxylic acid (ACC) in the petals (initial content 0.3 nmol/g fresh weight). Pretreatment of the flowers with silver thiosulfate (STS) retarded flower senescence and prevented the increase in ACC concentration in the petals. An increase in ACC in the remaining flower parts, which appeared to precede the increase in the petals, was only partially prevented by the STS pretreatment. Addition of aminoxyacetic acid (2 mM) to the solution in which the flowers were kept completely inhibited accumulation of ACC in all flower parts.

Changes in ethylene production and 1-aminocyclopropane-1-carboxylic acid content of pollinated carnation flowers

Pollination of flowers of standard carnation (Dianthus caryophyllus L. cv. White Sim) with pollen from flowers of miniature carnations (D. caryophyllus L. cv. Exquisite) caused them to wilt irreversibly within 1 to 2 days. Pollination stimulated a sequential increase in ethylene production by stigmas, ovaries, receptacles, and petals of the flowers. The ACC content of the stigmas increased rapidly in the first few hours after pollination. The possibility that subsequent production of ethylene by other parts of the flower is stimulated by translocated ACC is discussed. Ethylene production and ACC content of other parts of the flower reached their maximum 24 h after pollination. The petal tissues contributed the bulk of the ethylene productionper flower thereafter. There appears to be a qualitative difference between the enzyme in the stigmas converting ACC to ethylene and that in other parts of the flower.

Role of the ovary in carnation senescence.

Abstract Ovary growth in carnation flowers was inhibited by pre-treatments with silver thiosulfate which retarded petal senescence. Although the start of ovary growth preceded visible wilting of untreated flowers, the ovary does not appear to control carnation senescence. Its removal did not alter the time of senescence, and isolated petals wilted at the same time as those on intact flowers. The ovary normally competes weakly for metabolites with the petals; growth of the ovary occurred only when the petals were removed or started to senesce, if the sink strength of the ovary was increased by injecting growth regulators or if sucrose was supplied exogenously. It seems unlikely that the growth of the ovary is dependent on reallocation of carbohydrate materials from the petals.