TEMPERATURE VARIABILITY IS INTEGRATED BY A SPATIALLY-EMBEDDED DECISION-MAKING CENTER TO BREAK DORMANCY IN ARABIDOPSIS SEEDS
Topham, A.T.1, Taylor, R.E.1, Yan, D.2, Nambara, E.2, Johnston, I.G.1 and Bassel, G.W.1
1School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
2Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
Contact: George Bassel, firstname.lastname@example.org
Plants perceive and integrate information from the environment to time critical transitions in their life cycle. Some mechanisms underlying this quantitative signal processing have been described, while others await discovery. Seeds have evolved a mechanism to integrate environmental information by regulating the abundance of the antagonistically acting hormones ABA and GA. Here we show that hormone metabolic interactions and their feedbacks are sufficient to create a bistable developmental fate switch in Arabidopsis seeds. A digital single cell atlas mapping the distribution of hormone metabolic and response components revealed these to be enriched within the embryonic radicle, identifying the presence of a decision-making center within dormant seeds. The responses to both GA and ABA were found to occur within distinct cell types, suggesting crosstalk occurs at the level of hormone transport between these signaling centers. We describe theoretically, and demonstrate experimentally, that this spatial separation within the decision-making center acts to preferentially process variable temperature inputs from the environment to promote the breaking of dormancy. In contrast to other noise-filtering systems including human neurons, the functional role of this spatial embedding is to leverage variability in temperature to transduce a fate-switching signal within this biological system. Fluctuating inputs therefore act as an instructive signal for seeds enhancing the accuracy with which plants are established in ecosystems, and distributed computation within the radicle underlies this signal integration mechanism.
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