Protein disorder in crop stress adaptation

Global climate change has caused severe weather events such as droughts and high temperatures. These environmental stresses have severe impact on crop plant growth and food security such as fewer grains and smaller crop yields. Investigating how crop plants respond to environmental challenges is a fundamental issue in plant biology research and will raise strategic thinking for future sustainable agriculture.

This proposal aims at elucidating the role of protein disorder in crop plant stress responses as well as the mechanisms of action of the macromolecules involved in the underlying biological processes.

Intrinsically disordered proteins (IDPs) are a group of proteins natively lacking defined three-dimensional structures. The disordered features enable IDPs to have conformational flexibility and quick responsiveness to environmental stresses, thus serve as regulatory hubs and interact with various partners depending on different circumstances. Literatures suggest that IDPs may play critical roles in plant adaptation to environmental challenges.

For example, the abiotic stress-tolerant bioenergy crop switchgrass and the desiccation-tolerant resurrection grass have the highest proportion of proteins with intense disorder. Furthermore, tardigrade disordered proteins have been shown to play a crucial role in surviving desiccation. Disordered dehydrins have also been shown to protect plants under dehydration stress conditions. The precise functions and mechanisms of action are still largely unknown.

To understand the mechanism of IDPs involved in plant stress responses, the structural tool nuclear magnetic resonance (NMR) spectroscopy will be used in this study to map the conformational dynamics of IDPs and describe the mechanisms. Three stress responsive IDPs from rice and barley will be used as case studies to provide structural insight into protein disorder in plant stress responses.

Within this objective, a breakthrough technology in plant cell NMR method will be developed, which will benefit general plant biologists in terms of monitoring of plant protein dynamics and interaction in vivo in both the time and space dimensions and investigation on molecular mechanism of various developmental processes and stress responses.

IDPs are key triggers of liquid-liquid phase separation (LLPS) complexes, also known as biomolecular condensates, which allow the spatiotemporal organization of biochemical reactions by concentrating macromolecules locally. In this proposed research, proximity labeling of two stress-induced IDPs followed by affinity purification and identification of the protein components of LLPS complexes and verification of their interactions and LLPS properties via NMR and cell biology tools will address the function of LLPS in plant stress responses.

Since the current IDP databases are mainly focused on mammalian cells and biomedically related proteins, this study will establish the database regarding crop stress responsive IDPs, starting from rice and extending to other crops, which will benefit plant biologists who work on crop science and stress biology.

Given the increasing periods of heat and drought due to global climate change, it has become important to understand the strategies that crop plants utilize to cope with various stresses. The proposed research will provide new methods to study plant IDPs in stress responses, fundamental knowledge and mechanistic insights into plant stress physiology, and novel ideas for facing global climate change and solving food security problems.