Effect of Carbon Dioxide and Light on Ethylene Production in Intact Sunflower Plants

Abstract

High CO2 concentration (0.5%) increased the rate of ethylene production, measured in a continuous flow system, in intact sunflower (Helianthus auwus L.) plants. However, the rate of ethylene production subsided to near control levels after approximately 24 hours. The effect of high CO2 could only be observed in light. Although high CO2 concentration had no effect on the rate of ethylene production in darkness, prolonged exposure (approximately 16 hours) of plants to high CO2 in the dark prevented the increase in ethylene production when the plants were exposed to light and high C02.The interactions between CO2 and ethylene are of interest both for their role in the basic understanding of ethylene action in plants and for their use in preservation of produce, flowers, and fruits, etc. Little work has been done to study the effect of CO2 on the rate of ethylene production in plants. Aharoni and Lieberman (2) have reported recently that CO2 stimulates the ethylene production of tobacco leaf discs senescing in the dark. In an earlier report by Imaseki et al. (9), it was shown that the removal of CO2 from the atmosphere surrounding sweet potato tuber sections infected by black rot fungus decreased the rate of ethylene production. CO2 has been reported either to inhibit (15,20) or to have no effect (4) on ethylene production in ripening fruit but the results are difficult to interpret because of the possible effects of ethylene on its own production in these tissues (13).In most of the above cases, the experiments were done with excised plant parts sealed in closed systems. Numerous possible sources of error inherent in such techniques have already been pointed out (3,6). Further, with such systems it is not feasible to study the exact relationship between CO2 concentration and the rate of ethylene production on a temporal basis since the tissue is sealed for a considerable duration before sufficient amount of ethylene can accumulate to permit accurate analysis.Techniques have been developed in our laboratory that allow measurement of rate of ethylene production by the intact shoots of plants in a continuous flow system (3,6). Using these techniques, we have recently reported that an increase in the concentration of CO2 in the atmosphere surrounding the sunflower plants increased the rate of ethylene production (5). The change in rate of ethylene production was evident within the first few minutes of the carbon dioxide treatment. All the experiments reported in that paper were done in continuous light.The present study was undertaken to further explore the rela-'Financial assistance from the Natural Sciences and Engineering Re- MATERIALS AND METHODS The seedlings of sunflower (Helianthus annus L.) were started in trays containing vermiculite, in a constantly lit controlled environment growth chamber. The temperature in the growth chamber was maintained at 27 ± 1°C and the RH at 75%. After 7 d, the seedlings were transplanted to individual pots containing sand:vermiculite:peat moss (1:1:1).A 2-week-old plant ...

Bicarbonate/CO2-Facilitated Conversion of 1-Amino-cyclopropane-1-carboxylic Acid to Ethylene in Model Systems and Intact Tissues

“…Increased production of ethylene in response to enhanced levels of CO2 has been demonstrated for detached leaves and leaf discs of cocklebur (15), intact sunflower plants (6,12), tobacco leaf discs (1,2,18), and detached senescing oat leaves (14). The effect is obtained when CO2 is supplied either directly as a gas or indirectly as bicarbonate, and no increase in ethylene production ' is obtained when CO2 is removed with a KOH trap (15,18).…”

Sensitivity to 2,4-D in Sunflower as an Indicator of Tolerance to the Sunflower Midge (Diptera: Cecidomyiidae)

“…w house before testing. High light intensity before testing promotes ethylene production in the presence of CO 2 by increasing the activity of ACC oxidase in the last step of ethylene biosynthesis (Kao & Yang 1982, Bassi & Spencer 1982. Because the effect of 2,4-0 (promotion of ACC synthase, Fig.…”

“…Three replications of each hybrid were exposed to seven concentrations of 2,4-0 and a control. Because ethylene production is not affected by CO 2 concentration in the absence of light (Bassi & Spencer 1982), leaf disks were incubated in the dark. Because there may be a surge of ethylene production in response to the cutting of the disks (Suttle et al 1983), the jars were left open for the initial 2 h and sealed with lids fitted with a septum.…”

Ethylene Production by Attached Leaves or Intact Shoots of Tobacco Cultivars Differing in Their Speed of Yellowing during Curing

“…To date, there has been no report on ethylene measurements from single attached leaves incubated in an open system. In the present work, shoots or single leaves of intact plants were used for measurements of ethylene production.It is known that C02 affects the rate of ethylene evolution from tissues (6,11,16), presumably acting on the conversion of ACC4 to ethylene (16,19). However, there has been no report on the effect of CO2 on the possible differences in ethylene production among tissues at different stages of development.…”

“…It is known that C02 affects the rate of ethylene evolution from tissues (6,11,16), presumably acting on the conversion of ACC4 to ethylene (16,19). However, there has been no report on the effect of CO2 on the possible differences in ethylene production among tissues at different stages of development.…”