The authors say that their discovery could lay the groundwork for engineering crops that are able to harness FLOE1's abilities in order to withstand the detrimental effects of climate change. "We believe that this is the first study that provides information on how seeds can directly perceive their hydration state and act upon it," Rhee added. Because the FLOE1 aggregation is temporary and reversible, it can act as a go or no-go signal, halting germination if water availability is determined to be less than optimal, or allowing it to proceed if the environment has enough water to support successful growth. When a dormant seed senses moisture in its proximity, FLOE1 almost instantaneously assembles in the cell to test the waters, so to speak, and determine whether the conditions are good for the seed to reactivate and start growing.
"We found that FLOE1's ability to very quickly initiate this type of temporary gathering is crucial to its functionality." "Think of an organelle as an office building where components of the cell are assigned to complete their physiological jobs whereas, these phase-separation-enabled assemblies are more like a maker faire or hackathon, where proteins can come together to accomplish a task and then disburse when it's complete," Rhee said. This mechanism allows cells to dynamically compartmentalize biomolecules into membrane-less assemblies, rather than cordoning them off in a cellular organelle surrounded by a membrane. The key to FLOE1's capabilities is a recently discovered biophysical phenomenon that's a hot research topic right now called phase separation.
"So, a protein like FLOE1 is crucial to a plant's ability to walk the tightrope between too soon and too late." Once germination starts, the plant cannot go back into its hibernation state-the genie can't be put back in the bottle," Dorone explained.
"Despite the extraordinary toughness of many seeds, plants are still at their most vulnerable during this stage of their lives, because germination must be precisely timed to ensure the greatest chance of survival. Their findings have major implications for understanding plant ecology in a warming world and for the possibility of designing drought-resistant crops that can survive climate change and fight world hunger.ĭorone, Rhee, Boeynaems, Gitler, and their colleagues-including Carnegie's Benjamin Jin, Shannon Hateley, Flavia Bossi, Elena Lazarus, and Moises Exposito-Alonso-used molecular, physiological, and ecological research techniques to reveal a previously uncharacterized protein that they named FLOE1. New work jointly led by Carnegie's Yanniv Dorone and Sue Rhee and Stanford University's Steven Boeynaems and Aaron Gitler discovered a protein that plays a critical "go, or no-go" role in this process-halting germination if the soil's hydrological conditions are less than ideal or allowing it to proceed if the chances of survival are good. However, the mechanism by which the baby plant senses water and reactivates cellular activity has remained a mystery until now. This protects the embryonic plant inside from a variety of environmental stresses until conditions are favorable for growth and survival. Palo Alto, CA-Dehydrated plant seeds can lay dormant for long periods-over 1,000 years in some species-before the availability of water can trigger germination. view moreĬredit: Video is courtesy of Jannice G. Video: Electron tomographic reconstruction and segmentation of membrane-bound organelles (in blue) of an Arabidopsis embryo cell.
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