A Circadian Rhythm in the Level of the Carbon Dioxide Compensation Point in<i>Bryophyllum</i>and<i>Coffea</i>

Jones, Max; Mansfield, T. A.

doi:10.1093/jxb/21.1.159

Cited by 23 publications

(8 citation statements)

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“…T h e endogenous rhythm brings stomata into a state of preparedness to open (Mansfield & Heath, 1961 ;Stilfelt, 1963), as is evident from a decrease in osmotic potential (Stilfelt, 1967) and expansion (Stilfelt, 1965 ; of guard cells; actual opening occurs if light, temperature-increase or C0,-free air is given at the apposite phase of the rhythm. Thus, the three factors appear to play equivalent roles in opening; the similarities of their responses in rhythms are well documented (Wilkins, 1960(Wilkins, , 1962Jones & Mansfield, 1970, 1972. Accordingly, Mansfield ( 1 9 7 6~) suggests that stomata are merely exhibiting a pattern of behaviour that is common to several physiological processes, and argues that the 'tacit assumption ' that light is the principal promoter of opening is basically wrong.…”

Section: Are Stomatal Movements Controlled By L I G H T ?mentioning

confidence: 99%

Photocontrol of Stomatal Movements

Pemadasa

1981

Biological Reviews

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Summary 1. Opening in light is a feature common to the majority of functional stomata, but the current argument is against the traditional view that light is the principal environmental promoter of opening, because stomata can open in the dark in response to CO2 removal and/or temperature increase. In this review, evidence is provided that light is more efficient and effective than other physical factors in both producing and maintaining wide opening. However, light acts on stomata both directly and indirectly, in conjunction with changes in, for example, CO2 balance, water regime and temperature of the leaf tissue. 2. Three general categories of light effects on stomata are recognized: (a) photosynthetic effects driven by metabolic processes, induced or enhanced by light, (b) hydrophotic effects mediating through light‐induced changes in epidermal turgor, and (c) photothermal effects arising from light‐dependent changes in leaf temperature. 3. Photosynthetic effects involve both CO2 depletion, and starch mobilization, malate synthesis, H+ extrusion, and accumulation of K+ and C1‐ in guard cells; these processes are triggered by light of different qualities: (a) Both blue and red light are involved in photosynthetic CO2 fixation, utilizing energy from photosynthetic light reaction(s), which provides C precursors for synthesis of stornatal starch. (b) Blue light, but not red, enhances starch mobilization, PEP carboxylase activity and respiration. Accordingly, blue light is postulated to enhance hydrolysis of stornatal starch providing C3 precursors for malate synthesis via PEP‐fixation of endogenous CO2; the active extrusion of H+, derived from malate, is coupled with K+ influx to guard cells. Malate and C1‐ are competitive anions, for K+, and one begins to play a progressively more important role as the other becomes limiting; in intact leaves, however, malate plays a more decisive role. These processes are driven by the energy from blue‐light‐enhanced respiration. (c) Both photosynthetic fixation and PEP carboxylation act as CO2 sensors, but the exact role of CO2 in the stornatal mechanism has yet to be determined. 4. Hydrophotic and photothermal effects facilitate guard cell expansion by releasing epidermal pressure through enhanced evaporative water loss, and are, therefore, indirect effects of light; photothermal effects may also contribute to metabolic processes outlined in paragraph 3. 5. Stomatal closure in the dark accompanies starch synthesis, malate reduction, efflux of K+ and C1‐ from guard cells, and accumulation of CO2 in substomatal cavities. Malate may be converted to starch via C2 compounds. Guard cells release K+ and C1‐ into apoplastic space, from which they are removed by neighbouring cells. The entry of K+ into neighbouring cells is supposed to be coupled with H+ extrusion. These processes are dependent on respiratory energy. 6. The differential abaxial and adaxial stomatal light responses are related to inherent metabolic differences between the two epidermes, but the biochemical basis is not...

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Section: Are Stomatal Movements Controlled By L I G H T ?mentioning

confidence: 99%

Photocontrol of Stomatal Movements

Pemadasa

1981

Biological Reviews

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“…One reasonable hypothesis to explain the oscillating step response specifications would be that the CO2-concentration in the leaf varies in a circadian fashion (Jones and Mansfield 1970, Wilkins 1959,1960,1962a,b, 1967, Warren and Wilkins 1961, see also review by Queiroz 1974. This hypothesis is supported by the following facts:…”

Section: Transpiration Responses To 10 Mw/cm^ Magnitude Steps At mentioning

confidence: 99%

Regulation of Transpiration in Avena. Responses to White Light Steps

Brogårdh

Johnsson

1975

Physiologia Plantarum

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The transient responses in transpiration rate of the primary leaf of 8-days-old oat plants were studied when step changes in the white light irradiance were administered to the plants. A light or dark step was achieved by an instant increase or decrease, respectively, of the irradiance on the leaf surface. Usually the light step responses consisted of one rapid response (rise time 1-2 min) and one slow response (rise time 5-10 min). The dark step response had a fall time of about 10 min.At a high irradiance level and in CO2-free air the slow response disappeared. This could mean that the slow response is CO2controlled. The rapid response was still present under these conditions and is therefore probably caused by other processes than the slow response.In long time experiments several cycles of a circadian rhythm (period 26-28 h) could be followed in the light step responses. Thus the rapid response was small at that time of the day when the slow response was most pronounced and vice versa. The endogenous nature of the rhythm was established in phase-shift experiments. It is concluded that experiments on stomatal dynamics must take circadian variations into account.paper such specifications are studied in transpiratory step response experiments. Thus the influence of irradiance, CO2-concentration and diurnal rhythm on the dynamics of the water regulation of the plant are investigated. Material and Methods a. Plant materialOat plants (Avena sativa L. cv. Blenda, Svalof, Sweden), 8 days old, were used in the experiments. The plants were grown on a metal mesh in contact with tap water and were illuminated with white light (10 W/cm^, Osram L80 W/22) between 08:00 and 20:00 hours. For more details on the growth conditions, see Johnsson (1973).All responses except those in section g were studied in excised plants (without seed and root system). The excision was performed at the leaf base and in distilled water. The leaf base was then kept in distilled water throughout the experiment.

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“…Among higher plants, lightinduced electron flow (19) and carbohydrate partitioning (4,6) may be influenced by circadian rhythms. Gas exchange studies with several species have indicated diurnal changes in CO2 compensation points and dark respiration rates (7,17,21). Circadian rhythms in net assimilation under constant light with constant ambient CO2 levels have been reported for several species, including barley (10), peanut (21), and Chenopodium (7).…”

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Circadian Rhythms in Photosynthesis

Hennessey

Field²

1991

Plant Physiol.

145

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Net carbon assimilation and stomatal conductance to water vapor oscillated repeatedly in red kidney bean, Phaseolus vulgaris L., plants transferred from a natural photoperiod to constant light. In a gas exchange system with automatic regulation of selected environmental and physiological variables, assimilation and conductance oscillated with a free-running period of approximately 24.5 hours. The rhythms in carbon assimilation and stomatal conductance were closely coupled and persisted for more than a week under constant conditions. A rhythm in assimilation occurred when either ambient or intercellular CO2 partial pressure was held constant, demonstrating that the rhythm in assimilation was not entirely the result of stomatal effects on CO2 diffusion. Rhythms in assimilation and conductance were not expressed in plants grown under constant light at a constant temperature, demonstrating that the rhythms did not occur spontaneously but were induced by an external stimulus. In plants grown under constant light with a temperature cycle, a rhythm was entrained in stomatal conductance but not in carbon assimilation, indicating that the oscillators driving the rhythms differed in their sensitivity to environmental stimuli.The availability of light changes more rapidly and predictably over the course of a day than the level of any other resource essential for photosynthesis. Because the daily rhythm of light and darkness is so predictable, it is frequently used as the signal to entrain endogenous circadian rhythms. Circadian rhythms are ubiquitous among eukaryotic organisms and regulate a wide range of physiological and behavioral processes (5,11,25). Circadian rhythms have been described extensively in plants, but few studies have considered the role these rhythms may play in modifying photosynthetic rates in vascular plants. Circadian rhythms could play a potentially important role in coordinating photosynthetic activity with diurnal changes in light availability.Evidence from several approaches indicates that circadian rhythms influence photosynthetic processes. Rhythms in stomatal conductance are well documented and were described by Francis Darwin almost 100 years ago (9). More recently,

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A Circadian Rhythm in the Level of the Carbon Dioxide Compensation Point inBryophyllumandCoffea

Cited by 23 publications

References 0 publications

Photocontrol of Stomatal Movements

Photocontrol of Stomatal Movements

Regulation of Transpiration in Avena. Responses to White Light Steps

Circadian Rhythms in Photosynthesis

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