A team of researchers from multiple universities in Europe discovered a new mechanism that plants use to sense temperatures, according to a study published in PNAS. The authors believe these results could help find solutions to counteract some of the issues caused by early flowering and poor growth caused by climate change.
The increase in temperatures is having detrimental consequences for plants. In higher temperatures, plants tend to flower earlier and accelerate the reproductive process, lowering crop yields.
To understand this process, these researchers are working on the plants’ circadian rhythm, which controls growth and metabolism. The key protein in this mechanism is called Early Flowering 3 (EFL3). This protein reacts to various environmental clues, including light and temperature, to regulate the expression of certain genes that determine how plants grow and bloom.
Using the model plant Arabidopsis thaliana, the researchers found that, as temperature increases, ELF3 goes through a process called separation and can exist in two liquid phases.
“We believe that when it goes through phase separation, it sequesters different protein partners like transcription factors, which translates into faster growth and early flowering as a function of elevated temperature,” explained Chloe Zubieta, CNRS Research Director from the Laboratoire de Physiologie Cellulaire et Vegetale at the CEA Grenoble and co-corresponding author of the publication. “We are trying to understand the biophysics of the prion-like domain inside ELF3, which we think is responsible for this phase separation.”
ELF3 needs to be in solution, which means it cannot be studied using X-ray crystallography. Instead, the authors used X-ray scattering to find a highly disordered structure never seen before. “I’ve seen many prion-like domains involved in phase separation, but this is the first time I saw something fundamentally different,” said Mark Tully, ESRF scientist on BM29 and co-corresponding author of the publication.
The prion-like forms a large oligomer, which is key for phase separation. This oligomer appears to contain about 30 copies of the protein organised into a ball and acts as a scaffold, which is probably essential to interact with other proteins in the plant. When the team increased the temperature, the ELF3 balls got together to form a liquid phase and eventually an ordered stack.
“If we manage to tune when phase separation occurs as a function of temperature, by mutating different amino acid residues, we could ultimately delay flowering of plants under warmer conditions, allowing them to establish more biomass and make more fruits and seeds,” said Stephanie Hutin, a scientist at the CEA and first author of the paper. “Therefore, the next step in this research will be to add a different form of the ELF3 gene to the model plant Arabidopsis thaliana and to see what happens when we grow them at warm temperatures. If our model is correct, we could do the same in crop species that have trouble adapting to warmer conditions”, concluded the researcher.
Hutin S, Kumita JR, Strotmann VI, Dolata A, Ling WL, Louafi N, Popov A, Milhiet PE, Blackledge M, Nanao MH, Wigge PA, Stahl Y, Costa L, Tully MD, Zubieta C. Phase separation and molecular ordering of the prion-like domain of the Arabidopsis thermosensory protein EARLY FLOWERING 3. Proc Natl Acad Sci U S A. 2023 Jul 11;120(28):e2304714120. doi: 10.1073/pnas.2304714120