Genetic Discovery Reveals How Plants Respond to Blue Light and Cold

Background: Plants may be stuck in one place, but the world around them is constantly changing. In order to grow and flower at the right time, plants must constantly collect information about their surroundings, measuring things like temperature, brightness, and length of day. Still, it's unclear how all this information gets combined to trigger specific behaviors.

New findings: Scientists at the Salk Institute have discovered a genetic mechanism for how plants integrate light and temperature information to control their flowering.

In a new study published in Nature Communications on August 26, 2025, the researchers found an interaction between two genetic pathways that signals the presence of both blue light and low temperature. This genetic module helps plants fine-tune their flowering to the optimal environmental conditions.

In one pathway, blue light activates the PHOT2 blue light receptor, with help from partner protein NPH3. In another pathway, low ambient temperature allows a transcription factor called CAMTA2 to boost the expression of a gene called EHB1. Importantly, EHB1 is known to interact with NPH3, placing NPH3 at the convergence point of the blue light and low temperature signals. This genetic architecture effectively works as a coincidence detector, linking the presence of blue light and low temperature to guide the switch to flowering.

Why this is important: The Salk study describes an important component of plant growth, reproduction, and information processing. The newly discovered genetic module allows plants to have fine control over their flowering in low temperatures. Understanding this system will now help Salk's Harnessing Plants Initiative optimize crop growth under changing environmental conditions. 

Author quote: "When animals don't like the environment that they are in, they move," says first author of the study Adam Seluzicki, a staff researcher at Salk. "Plants don't have this option, so they collect as much information as they can to understand their environment and respond appropriately. We have now discovered a genetic system that plants use to combine blue light and low temperature information to regulate an important step in their growth and reproduction, which will have important implications for future food production."

Other authors: Other authors include Joanne Chory of Salk. This manuscript is dedicated to Chory, one of the world's most influential plant biologists, who passed away on November 12, 2024.

Funding: The work was supported by the National Institutes of Health (R35 GM122604, P30 014195, S10 OD026929), the Howard Hughes Medical Institute, the Chapman Foundation, the Helmsley Charitable Trust, and the Salk Institute Pioneer Postdoctoral Endowment Fund.