Plant biologists discover how sunflowers use internal circadian timing to follow the sun
Originally shared by Rob Jongschaap
Plant biologists discover how sunflowers use internal circadian timing to follow the sun
'... How do the plants move their stems during the day? Atamian put ink dots on the stems and filmed them with a video camera. On a time-lapse video, he could measure the changing distance between the dots.
When plants were tracking the sun, the east side of the stem grew more rapidly than the west side, he found. At night, the west side grew faster as the stem swung the other way. The team identified a number of genes that were expressed at higher levels on the sunward side of the plant during the day, or on the other side at night.
Harmer said that there appear to be two growth mechanisms at work in the sunflower stem. The first sets a basic rate of growth for the plant, based on available light. The second, controlled by the circadian clock and influenced by the direction of light, causes the stem to grow more on one side than another, and therefore sway east to west during the day.
As the sunflower matures and the flower opens up, overall growth slows and the plant stops moving during the day and settles down facing east. This seems to be because the circadian clock ensures that the plant reacts more strongly to light early in the morning than in the afternoon or evening, so it gradually stops moving westward during the day.
...'
http://www.deepstuff.org/plant-biologists-discover-sunflowers-use-internal-circadian-timing-follow-sun/
http://www.deepstuff.org/plant-biologists-discover-sunflowers-use-internal-circadian-timing-follow-sun/
Plant biologists discover how sunflowers use internal circadian timing to follow the sun
'... How do the plants move their stems during the day? Atamian put ink dots on the stems and filmed them with a video camera. On a time-lapse video, he could measure the changing distance between the dots.
When plants were tracking the sun, the east side of the stem grew more rapidly than the west side, he found. At night, the west side grew faster as the stem swung the other way. The team identified a number of genes that were expressed at higher levels on the sunward side of the plant during the day, or on the other side at night.
Harmer said that there appear to be two growth mechanisms at work in the sunflower stem. The first sets a basic rate of growth for the plant, based on available light. The second, controlled by the circadian clock and influenced by the direction of light, causes the stem to grow more on one side than another, and therefore sway east to west during the day.
As the sunflower matures and the flower opens up, overall growth slows and the plant stops moving during the day and settles down facing east. This seems to be because the circadian clock ensures that the plant reacts more strongly to light early in the morning than in the afternoon or evening, so it gradually stops moving westward during the day.
...'
http://www.deepstuff.org/plant-biologists-discover-sunflowers-use-internal-circadian-timing-follow-sun/
http://www.deepstuff.org/plant-biologists-discover-sunflowers-use-internal-circadian-timing-follow-sun/
Like a giant sun dial ,they follow the sun and then Sims.
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