A recent study employs a range of groundbreaking field experiments to demonstrate how plants merge signals from their circadian clocks with environmental factors in ever-changing natural settings.
Much of our understanding of plant circadian rhythms stems from controlled laboratory experiments where factors like light and temperature can be meticulously managed.
However, there is limited knowledge on how these biological timing mechanisms function in the unpredictably dynamic natural world, where they have evolved to synchronize living organisms with daily and seasonal rhythms.
A groundbreaking joint study between researchers from the UK and Japan has made strides to bridge this gap with a series of inventive field experiments that reveal how plants integrate clock signals with environmental indicators in naturally variable conditions.
This collaborative team, comprising members from the John Innes Centre, Kyoto University, and The Sainsbury Laboratory in Cambridge, has developed statistical models based on these field studies, which may enhance our understanding of how plants, including major crops, could adapt to future temperature changes.
“Our research underscores the importance of international partnerships in advancing scientific knowledge across disciplines,” stated senior author Professor Antony Dodd, a group leader at the John Innes Centre. “It’s captivating to see the mechanisms we identified in laboratory settings also influencing plants in their natural environments.”
Professor Hiroshi Kudoh from Kyoto University commented, “Every living system has evolved within the framework of its natural surroundings. There is much work to be done to evaluate the genetic systems’ functions in natural contexts. This study represents the first steps in such an essential investigation.”
A prior study led by Professor Dodd identified a genetic pathway regulated by the biological clock, which protects photosynthesizing plants from cellular damage in extreme bright and cold conditions.
In the current study, published in Proceedings of the National Academy of Sciences (PNAS), the research team aimed to identify this same mechanism in real-world scenarios, drawing on substantial prior research led by Professor Hiroshi Kudoh.
Through two field studies near the March and September equinoxes, they examined a natural population of Arabidopsis halleri plants at a rural field site in Japan.
The researchers tracked how gene expression in the plants changed over 24-hour cycles as light and temperature varied.
They extracted RNA from the plants every two hours, preserved these samples by freezing, and transported them back to the lab for analysis to monitor gene expression levels in the plant tissues.
The team also devised equipment to manipulate the temperatures around the plants, allowing them to replicate laboratory conditions from their earlier work.
Plants respond acutely to red and blue light, prompting the researchers to use green filters on their headlamps to ensure they remained invisible to the plants during nighttime visits.
“Identifying plants with a green head torch in the pouring rain at night is surprisingly challenging,” noted Professor Dodd.
Using data gathered from their samples, the researchers identified patterns in gene expression within the already established genetic pathway that connects insights from the plant’s circadian clock with signals from light and temperature.
Their findings indicated that plants in the wild exhibit the same sensitivity to cold and bright dawn conditions that had been noted in earlier laboratory experiments.
Based on this data, the team constructed statistical models that can accurately predict how circadian clock-regulated gene activity responds to environmental signals throughout the day in natural settings.
“We believe this is the first instance of modeling an entire circadian clock signaling pathway in plants growing outside,” remarked Professor Dodd.
“If we can develop models to accurately predict gene expression in response to environmental factors, it may be possible to breed plants capable of adapting to changing climate conditions.”
Dr. Haruki Nishio from Shiga University, a co-first author of the study, stated: “The versatility of Bayesian time-series modeling enabled us to untangle complex signal integration within natural environments, proving particularly effective for studies in challenging ecological contexts.”
This research focused on plant responses at the gene expression level. The next phase of this work will involve applying the statistical models developed to physiological functions in plants, such as photosynthesis rates and temperature adaptability.
Dr. Dora Cano-Ramirez, a circadian clock researcher currently at The Sainsbury Laboratory, Cambridge University, and another co-first author, commented: “The circadian clock controls many crucial plant processes, as demonstrated in laboratory studies, but we have not fully understood how these processes translate into field conditions until now.”
“Grasping how circadian-regulated processes align with variable environments through modeling this signaling pathway could assist in anticipating plant responses in an increasingly uncertain climate.”
“Circadian and environmental signal integration in a natural population of Arabidopsis,” is detailed in PNAS.
