Photosynthetic patterning: a mechanism for sun tracking

Fisher, F. J. F.; Fisher, Penny

doi:10.1139/b83-290

Cited by 12 publications

(10 citation statements)

References 14 publications

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“…While two previous studies (8,9) indicated that photosynthetic activity and ambient CO2 concentrations affected heliotropic leaf movements in Lavatera cretica, we did not observe any dependence on these factors in P. vulgaris. Our results are in agreement with Koller's (15) suggestion that photosynthesis does not play any role in perception of vectorial excitation in heliotropic movements.…”

Section: Discussioncontrasting

confidence: 99%

Heliotropic Leaf Movements in Common Beans Controlled by Air Temperature

Fu¹,

Ehleringer²

1989

Plant Physiol.

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Heliotropic leaf movements were examined in common beans (Phaseolus vulgaris cv Blue Lake Bush) under outdoor and laboratory conditions. Heliotropic leaf movements in well-watered plants were partly controlled by temperature, and appeared to be independent of atmospheric humidity and CO2 concentration. When environmental conditions were held constant in the laboratory, increased air temperature caused bean leaves to orient more obliquely to a light source. Ambient C02, intercellular C02, and net photosynthesis were not correlated with the temperatureinduced changes in heliotropic movements, nor did they significantly affect these movements directly. The effect of air temperature on leaf movements need not be mediated through a change in leaf water potential, transpiration, or leaf conductance. Air temperature modified laminar orientation in light through its effect on tissue temperature in the pulvinal region, not that of the lamina or petiole. However, under darkness the temperature effects on leaf movements were not expressed. Active heliotropic movements in response to air temperature allowed lamina temperature to remain close to the thermal optimum of photosynthesis. This temperature effect underlies a commonly observed pattem of leaf movements under well-watered conditions: a tendency for leaves to face the sun more obliquely on hot days than cool days.Active and continuous leaf movements in response to the movement of the sun (heliotropic leaf movements) have been described for a large number of native plants and crops (3,6,7). Species with heliotropic movements orient their leaves perpendicularly, obliquely or parallel to the sun's direct rays, thus regulating the radiant energy incident by the leaf lamina. Heliotropic leaf movements are induced by blue light (15,24,26,28). The site of light perception is located at the pulvinus in the Fabaceae (15,22,24,25,27), and in the leaf lamina in the Malvaceae (16,23). Fisher and Wright (9) report that the heliotropic response was eliminated in the absence of ambient C02, suggesting an essential requirement of positive net photosynthesis for heliotropic leafmovements in Lavatera cretica. However, Koller (15) argued that it was unlikely that photosynthetic activity played any role in perception of vectorial excitation, since photosynthetically active red light was ineffective for vectorial excitation (23, 29). While many observations have shown that heliotropic leaf movements are controlled by vectorial light (15-17, 23, 27), little attention has been given to the possible dependence of heliotropic move- ' Supported by grants from the National Science Foundation and U.S. Department of Agriculture-Competitive Research Grants Office.

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Section: Discussioncontrasting

confidence: 99%

Heliotropic Leaf Movements in Common Beans Controlled by Air Temperature

Fu¹,

Ehleringer²

1989

Plant Physiol.

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“…The mechanism by which leaves perceive iight direction is stiil unknown. A photosynthetic mechanism for vectoriai iight sensing such as that proposed for Lavatera cretica (Fisher and Fisher 1983) is unlikely in Lupinus succulentus because the site of light perception is located in the pulvinus, not the lamina. In addition, a photosynthetic model predicts that leaves would re-spond equally well to blue or red light, but thus far only blue light has been demonstrated to activate solar tracking in Lupinus succulentus (Vogelmann and Bjorn 1983), Malva neglecta (Yin 1938), and Lavatera cretica (Koller 1980).…”

Section: Resultsmentioning

confidence: 99%

“…In L. succulentus, an irradiation period as short as 1 h can activate leaf movement which proceeds at a maximum measured velocity of 15° h^^ Only blue light is effective (Vogehnann and Bjorn 1983) and in both Lavatera cretica and Lupinus succulentus only the upper leaf surface is sensitive to vectorial light. Recently, a photosynthetic mechanism has been proposed as a hypothesis for vectorial light perception in Lavatera cretica (Fisher and Fisher 1983). Here it was proposed that microshading of leaf veins by smal!…”

Section: Introductionmentioning

confidence: 99%

Site of light perception and motor cells in a sun‐tracking lupine (Lupinus succulentus)

Vogelmann

1984

Physiologia Plantarum

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Vogelmann, T. C, 1984. Site of light perception and motor ceils in a sun-tracking lupme (Lupinus succulentus). -Physioi. Plant, 62: 335-340.From the results of shading experiments and irradiation of leaves from different directions, the pulvinus has been identified as the site of light perception in leaves of tne sun-tracker, Luptnus succulentus Dougl. Within the pulvinus, the light-sensitive region IS located on the adaxial surface of the base of each leaflet. This is coincident with the site of the motor cells which are located in the peripheral four cell layers Motor cells were visualized by microscopy and undergo dramatic changes in cel! volume as leaflets incline to orient perpendicular to an oblique beam of light Communication between leaflets appears to be minimal because each leaflet has the capacity to perceive and orient towards a light beam independently of the others Hypotheses for the mechanism of directional light perception are discussed.Additional key words -Diahelionasty, diaheliotropism, phototropism, pulvinus solar-trackmg. f < trequests).

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“…3, using a two degree positive displacement in the direction of irradiation as datum: L (left) and R (right) indicates light direction). According to the differential photosynthate hypothesis (Fisher & Fisher, 1983b), movements are triggered by photosynthate gradients across the pulvinar phloem! Under normal conditions of photosynthesis, photosynthate concentrations in actively translocating phloem would be expected to remain high (Esau, 1969).…”

Section: Discussionmentioning

confidence: 99%

THE DEPENDENCE OF SUNTRACKING IN LAVATERA CRETICA L. UPON CARBON DIOXIDE AVAILABILITY

Fisher

Wright²

1984

New Phytologist

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SUMMARYWhen CO2 is withheld from the leaves of Lavatera cretica L., the normal phototropic tracking response to an oblique light source becomes weakened within 60 min and after 2 h is eliminated altogether. If CO2 is also withheld throughout a preceding 24 h dark period, even the initial tracking response in the light under carbon dioxide deprivation is eliminated. Normal tracking resumes in both cases when CO2 is again provided. Alternating directions of oblique illumination, under normal atmospheric COj levels, produce a synchronized response cycle with a short phase lag, but carbon dioxide deprivation results in the adoption of a neutral intermediate position.The results are in accord with the hypothesis that uneven distribution patterns in photosynthetic activity, resulting from the oblique illumination of the lamina, lead to the pulvinar turgor gradients responsible for suntracking movements in this species.

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Photosynthetic patterning: a mechanism for sun tracking

Cited by 12 publications

References 14 publications

Heliotropic Leaf Movements in Common Beans Controlled by Air Temperature

Heliotropic Leaf Movements in Common Beans Controlled by Air Temperature

Site of light perception and motor cells in a sun‐tracking lupine (Lupinus succulentus)

THE DEPENDENCE OF SUNTRACKING IN LAVATERA CRETICA L. UPON CARBON DIOXIDE AVAILABILITY

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