This project seeks to understand how plants sense and respond to heat stress. This is an important topic for society because virtually all the food we consume is ultimately dependent on plants. The productivity of plants is highly influenced by heat stress. For example, it has been predicted that for every additional 1 ºC temperature increase as a consequence of climate change, crop yields of staples such as wheat and rice will decrease by about 10 %. Global food security is therefore at a high risk from increasing heat waves that can have major impacts on agricultural yields. Climate change is causing hotter, drier, summers and these are becoming more frequent. Despite the major importance of this topic, we understand relatively little about how plants actually sense and respond to heat. Work in my group has lead to the discovery of several mechanisms by which plants sense and respond to temperature. One particularly interesting temperature sensor involves protein phase change. During protein phase change, proteins are able to change from being fully soluble in a watery solution to being in droplets, much like a salad dressing separates into oil and vinegar.
This ability of proteins to sense temperature by undergoing "phase change" reflects a major temperature sensing mechanism in plants. This grant seeks to capitalize on this discovery and expand our understanding of how plants sense temperature in this way. By understanding how molecules in plants sense temperature, we ultimately aim to breed new crops that are more resilient to climate change. This will help safeguard food security.
Before we are able to directly work on crop plants, for this project we must first make fundamental discoveries about how protein phase change in response to temperature occurs. This work is done in the model plant Arabidopsis thaliana, since this is the most thoroughly understood plant from a scientific perspective owing to its excellent tractability as a model system.
Specific objectives of this project include:
-Determining how the amino-acid sequence of proteins controls the protein phase change response to temperature
We are identifying proteins that contain particular sequence motifs that confer temperature dependent phase change. We are then analyzing these sequences to identify the features that trigger temperature responsiveness. The goal of this objective is to understand thermosensing with sufficient clarity that we are able directly engineer new temperature responsive behavior by altering the amino acid composition of temperature responsive proteins.
-Identifying the temperature responsive proteome
Major advances in studying how proteins work in the cell now make it possible to study how proteins respond to temperature in the cell directly. We are therefore analyzing the cellular proteome to identify the major temperature responsive proteins. By comparing these with proteins that contain protein phase change sequence motifs, we are able to identify the proteins that likely undergo protein phase change and are thermally responsive. This will allow us to create a comprehensive understanding of the key thermosensors of the cell.
-Understanding how protein production is altered by temperature
As well as protein activity, the synthesis of some proteins by translation is also influenced by temperature. For example, RNA can adapt different conformations at different temperatures. We will investigate to see if these mechanisms are widely used in plants to sense and respond to temperature.
-Engineering desired temperature response pathways in plants. By taking the combined knowledge of both how proteins as well as mRNA responds to temperature, we will seek to engineer desired temperature responsive networks in cells. We will try this in both yeast, since it is a very tractable model system, as well as Arabidopsis.
