By: Fariss Samarrai | University Communications
It’s summertime, and fields are colored with an array of flowering plants – some of them sunflowers – that are dutifully watching the rising sun. Plant biologists at the University of Virginia and two universities in California have now discovered how young sunflowers use their internal circadian clock – acting through growth hormones – to follow the sun from east to west during the day, then return to face east by dawn as they grow.
“Many studies have examined the plants’ clocks’ role in modulating growth under controlled conditions, but this is really one of the first to show that under ever-changing natural conditions out in the field, the clock works with light cues to direct growth in ways that have major consequences for biomass and reproduction,” said one of the study authors, biologist Benjamin Blackman of UVA and the University of California, Berkeley. He conducted his research supported by a National Science Foundation grant from the Plant Genome Research Program at a field site at UVA’s Morven Farm, along with former Harrison Undergraduate Research Scholar Evan Brown, a 2014 UVA alumnus.
The paper appears in the current edition of the journal Science.
Blackman worked with Stacey Harmer, a University of California, Davis molecular biologist who studies plant circadian clocks. Harmer’s lab previously had discovered links between “clock” genes and the plant hormone auxin, which regulates growth. But Harmer and Blackman needed an example to work on, and they found it in the sunflower.