In a collaborative study, researchers from the UK and Japan conducted innovative field experiments to better understand how plants integrate circadian clock signals with environmental cues under natural conditions. This pioneering work involved scientists from the John Innes Centre, Kyoto University, and The Sainsbury Laboratory, Cambridge, and led to the development of statistical models that may predict how plants, including major crops, could respond to future climate changes.
"Our research highlights the value of international collaboration in cross-disciplinary scientific progress," said senior author Professor Antony Dodd, a group leader at the John Innes Centre. "It is fascinating to see how processes we have identified in the lab also work to influence plants under natural conditions."
Professor Hiroshi Kudoh from Kyoto University added, "Any living system has evolved in the context of its natural habitat. A great deal of work lies ahead to assess the function of genetic systems under natural conditions. This study was designed as one of the beginnings of such an endeavour."
Previously, Professor Dodd's team identified a genetic pathway controlled by the circadian clock that protects photosynthesizing plants from cellular damage in bright, cold conditions. The current study, published in 'PNAS', sought to identify this mechanism in nature, building on extensive "in natura" research led by Professor Kudoh.
The researchers conducted two field studies around the March and September equinoxes, analyzing a natural population of 'Arabidopsis halleri' in a rural Japanese field. They tracked gene expression changes in the plants over 24-hour cycles as light and temperature varied. The experiments involved collecting RNA samples from the plants every two hours, freezing them, and later analyzing them in the lab to monitor gene expression in the tissues.
The team also developed equipment to manipulate temperatures around the plants, replicating lab conditions in the field. Given that plants are highly sensitive to red and blue light, researchers wore green filters over their head torches during nocturnal visits to avoid affecting the results. "It is surprising how difficult it is to identify green plants with a green head torch in the middle of the night, in pouring rain," remarked Professor Dodd.
The researchers observed that wild plants showed the same sensitivity to cold and bright dawn conditions that had been noted in laboratory experiments. Using this data, they developed statistical models that accurately predict how gene expression regulated by the circadian clock responds to environmental signals throughout the day.
"We believe this is the first time anyone has modelled a whole circadian clock signaling pathway in plants growing outdoors," said Professor Dodd. "If we can produce models that can accurately predict gene expression in relation to environmental conditions, then it may be possible to breed plants that are able to adapt to future climate conditions."
Dr. Haruki Nishio from Shiga University, joint first author of the study, explained, "The flexibility of Bayesian time-series modelling allowed us to disentangle complex signal integration in natural environments. This approach has proven particularly effective for studies conducted in intricate environmental settings."
This study focused on plant responses at the gene expression level. The next phase of research will apply the statistical models developed here to plant physiological functions, such as photosynthesis rates or temperature adaptation.
Dr. Dora Cano-Ramirez, a circadian clock researcher now at the Sainsbury Laboratory Cambridge University and joint first author of the research, said: "The circadian clock regulates many key plant processes as shown in studies under laboratory settings; however, we have not known the extent to which these processes translate to field conditions until now." She added, "Understanding how circadian-regulated processes are aligned with a fluctuating environment by modeling this signaling pathway, could be useful in predicting plant responses in an increasingly unpredictable climate."
Research Report:Circadian and environmental signal integration in a natural population of Arabidopsis
Related Links
John Innes Centre
Understanding Time and Space
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