Cell-type-specific environmental signal integration networks controlling a binary developmental switch during the life cycle of plants

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A growing human population is placing increasing demands on agriculture, with current production needing to double by the year 2050. Compounding this challenge are the effects of climate change which are limiting the yields we have previously come to expect. The need to develop crop varieties resistant to the yield-limiting effects of environmental change is urgent. The information generated by this project will be vital to the successful development of new crop varieties with sustainably high yields across a range of environmental conditions.In order to ensure their survival and reproductive success, plants have evolved the ability to alter the timing of decisions during their life cycle in response to a wide variety of signals from their environment. Key choices during plant development include the decision to reproduce, or start flowering, and the decision to commence growth, which begins with the germination of their seeds. Both of these transitions are influenced by more than one cue from the environment, including light, temperature and nutrients. The process of signal integration describes the incorporation of multiple pieces of information into a single verdict. This amalgamation of information occurs in plants through a complex series of interactions between various molecules. This project will use seed germination as a model system to understand how diverse environmental signals are integrated into a single binary decision, to terminate dormancy and start germination. Many individual factors mediating seed responses to the environment have been uncovered previously. What is not known is how these individual components interact with one another to form a signal integration network. This proposal will fill this gap in our understanding by defining the molecular network which plants use to merge diverse environmental cues into a single decision to commence their growth. The project will as well define previously uncharacterized components of the signal integration process, and explain how information from the environment is passed onto the final molecular targets that drive the final decision.It is well known that plants use multiple pieces of information to guide their developmental transitions, yet it much less clear in which cells this decision-making process occurs. The proposal will investigate the role of a specialized sub-group of cells within the plant embryo that we have recently uncovered as a site where diverse signals are integrated into a single decision. The way the environment controls the signal integration network within each of these cells will be determined, characterizing a cellular decision-making centre in plants. The information derived from this project will represent a step change in our ability to develop crop plants with robust yields across a wide range of environmental conditions. Previous attempts to modify plant response to the environment using individual components have been met with limited success, largely due to the lack of understanding of how these isolated factors exert their influence through a complex series of interactions within molecular signal integration networks. In order to accurately and robustly modify plant response to the environment, we must first understand what these networks are, and how they function to control plant responses. This knowledge can be used to tactically perturb key interactions, rather than individual components, to achieve a desired output.Another factor limiting the success of modifying plant response to the environment is a lack of understanding of the spatial control of these processes. Distinct decisions are made within distinct sites. The ability to target modifications to interactions present within specific cells that are making key decisions will greatly enhance our ability to modify plant behaviour in response to the environment.