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Horváth G, Slíz-Balogh J, Horváth Á, Egri Á, Virágh B, Horváth D, Jánosi IM. Sunflower inflorescences absorb maximum light energy if they face east and afternoons are cloudier than mornings. Sci Rep 2020; 10:21597. [PMID: 33299003 PMCID: PMC7725789 DOI: 10.1038/s41598-020-78243-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/17/2020] [Indexed: 11/09/2022] Open
Abstract
The mature inflorescence of sunflowers (Helianthus annuus) orients eastward after its anthesis (the flowering period, especially the maturing of the stamens), from which point it no longer tracks the Sun. Although several hypothetical explanations have been proposed for the ecological functions of this east facing, none have been tested. Here we propose an atmospheric-optical explanation. Using (i) astronomical data of the celestial motion of the Sun, (ii) meteorological data of diurnal cloudiness for Boone County located in the region from which domesticated sunflowers originate, (iii) time-dependent elevation angle of mature sunflower heads, and (iv) absorption spectra of the inflorescence and the back of heads, we computed the light energy absorbed separately by the inflorescence and the back between anthesis and senescence. We found that the inflorescences facing east absorb the maximum radiation, being advantageous for seed production and maturation, furthermore west facing would be more advantageous than south facing. The reason for these is that afternoons are cloudier than mornings in the cultivation areas of sunflowers. Since the photosynthesizing green back of mature heads absorbs maximal energy when the inflorescence faces west, maximizing the energy absorbed by the back cannot explain the east facing of inflorescences. The same results were obtained for central Italy and Hungary, where mornings are also less cloudy than afternoons. In contrast, in south Sweden, where mornings are cloudier than afternoons, west-facing mature inflorescences would absorb the maximum light energy. We suggest that the domesticated Helianthus annuus developed an easterly final orientation of its mature inflorescence, because it evolved in a region with cloudier afternoons.
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Affiliation(s)
- Gábor Horváth
- Environmental Optics Laboratory, Department of Biological Physics, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary.
| | - Judit Slíz-Balogh
- Environmental Optics Laboratory, Department of Biological Physics, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary.,Department of Astronomy, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary
| | - Ákos Horváth
- Meteorological Institute, Universität Hamburg, Bundesstrasse 55, 20146, Hamburg, Germany
| | - Ádám Egri
- Danube Research Institute, MTA Centre for Ecological Research, Karolina út 29-31, 1113, Budapest, Hungary
| | - Balázs Virágh
- Environmental Optics Laboratory, Department of Biological Physics, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary
| | - Dániel Horváth
- Environmental Optics Laboratory, Department of Biological Physics, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary
| | - Imre M Jánosi
- Department of Physics of Complex Systems, ELTE Eötvös Loránd University, Pázmány sétány 1, 1117, Budapest, Hungary
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Atamian HS, Creux NM, Brown RI, Garner AG, Blackman BK, Harmer SL. Circadian regulation of sunflower heliotropism, floral orientation, and pollinator visits. Science 2016; 353:587-90. [PMID: 27493185 DOI: 10.1126/science.aaf9793] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/15/2016] [Indexed: 11/02/2022]
Abstract
Young sunflower plants track the Sun from east to west during the day and then reorient during the night to face east in anticipation of dawn. In contrast, mature plants cease movement with their flower heads facing east. We show that circadian regulation of directional growth pathways accounts for both phenomena and leads to increased vegetative biomass and enhanced pollinator visits to flowers. Solar tracking movements are driven by antiphasic patterns of elongation on the east and west sides of the stem. Genes implicated in control of phototropic growth, but not clock genes, are differentially expressed on the opposite sides of solar tracking stems. Thus, interactions between environmental response pathways and the internal circadian oscillator coordinate physiological processes with predictable changes in the environment to influence growth and reproduction.
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Affiliation(s)
- Hagop S Atamian
- Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Nicky M Creux
- Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Robin Isadora Brown
- Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA
| | - Austin G Garner
- Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA
| | - Benjamin K Blackman
- Department of Biology, University of Virginia, PO Box 400328, Charlottesville, VA 22904, USA. Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA
| | - Stacey L Harmer
- Department of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
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Detecting leaf pulvinar movements on NDVI time series of desert trees: a new approach for water stress detection. PLoS One 2014; 9:e106613. [PMID: 25188305 PMCID: PMC4154739 DOI: 10.1371/journal.pone.0106613] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 08/02/2014] [Indexed: 11/23/2022] Open
Abstract
Heliotropic leaf movement or leaf ‘solar tracking’ occurs for a wide variety of plants, including many desert species and some crops. This has an important effect on the canopy spectral reflectance as measured from satellites. For this reason, monitoring systems based on spectral vegetation indices, such as the normalized difference vegetation index (NDVI), should account for heliotropic movements when evaluating the health condition of such species. In the hyper-arid Atacama Desert, Northern Chile, we studied seasonal and diurnal variations of MODIS and Landsat NDVI time series of plantation stands of the endemic species Prosopis tamarugo Phil., subject to different levels of groundwater depletion. As solar irradiation increased during the day and also during the summer, the paraheliotropic leaves of Tamarugo moved to an erectophile position (parallel to the sun rays) making the NDVI signal to drop. This way, Tamarugo stands with no water stress showed a positive NDVI difference between morning and midday (ΔNDVImo-mi) and between winter and summer (ΔNDVIW-S). In this paper, we showed that the ΔNDVImo-mi of Tamarugo stands can be detected using MODIS Terra and Aqua images, and the ΔNDVIW-S using Landsat or MODIS Terra images. Because pulvinar movement is triggered by changes in cell turgor, the effects of water stress caused by groundwater depletion can be assessed and monitored using ΔNDVImo-mi and ΔNDVIW-S. For an 11-year time series without rainfall events, Landsat ΔNDVIW-S of Tamarugo stands showed a positive linear relationship with cumulative groundwater depletion. We conclude that both ΔNDVImo-mi and ΔNDVIW-S have potential to detect early water stress of paraheliotropic vegetation.
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Okazaki Y. Blue light inactivates plasma membrane H(+)-ATPase in pulvinar motor cells of Phaseolus vulgaris L. PLANT & CELL PHYSIOLOGY 2002; 43:860-868. [PMID: 12198188 DOI: 10.1093/pcp/pcf099] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Unilateral blue light irradiation induces bending of pulvini of Phaseolus vulgaris towards the source of light. The pulvinar bending is caused by a decrease in turgor pressure of motor cells that are irradiated with blue light. Decrease in the turgor pressure is caused by the net efflux of K(+) and counter anions, accompanying membrane depolarization. In the present study the effect of blue light on the activity of plasma membrane H(+)-ATPase was studied in relation to the membrane depolarization. The activity of the plasma membrane H(+)-ATPase was measured using protoplast suspensions prepared from laminar pulvini from primary leaves. A pulse of blue light under continuous red light irradiation induced both a transient increase in the external pH and transient inhibition of the vanadate-sensitive ATPase. Continuous blue light irradiation under continuous red light irradiation induced both a sustained increase in the external pH and sustained inhibition of the vanadate-sensitive ATPase. These results show that blue light inhibits the activity of the plasma membrane H(+)-ATPase. Inactivation of the plasma membrane H(+)-ATPase supports the membrane depolarization induced by the blue light irradiation.
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Affiliation(s)
- Yoshiji Okazaki
- Department of Biology, Osaka Medical College, Sawaragicho 2-41, Takatsuki, 569-0084 Japan.
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