Plants can be larks or night owls just like us

Plants have the same variation in body clocks as that found in humans, according to new research that explores the genes governing circadian rhythms in plants.

The research shows a single letter change in their DNA code can potentially decide whether a plant is a lark or a night owl. The findings may help farmers and crop breeders to select plants with clocks that are best suited to their location, helping to boost yield and even the ability to withstand climate change.

The circadian clock is the molecular metronome which guides organisms through day and night – cockadoodledooing the arrival of morning and drawing the curtains closed at night. In plants, it regulates a wide range of processes, from priming photosynthesis at dawn through to regulating flowering time.

These rhythmic patterns can vary depending on geography, latitude, climate and seasons – with plant clocks having to adapt to cope best with the local conditions.

Researchers at the Earlham Institute and John Innes Centre in Norwich wanted to better understand how much circadian variation exists naturally, with the ultimate goal of breeding crops that are more resilient to local changes in the environment – a pressing threat with climate change.

To investigate the genetic basis of these local differences, the team examined varying circadian rhythms in Swedish Arabidopsis plants to identify and validate genes linked to the changing tick of the clock.

Dr Hannah Rees, a postdoctoral researcher at the Earlham Institute and author of the paper, said: “A plant’s overall health is heavily influenced by how closely its circadian clock is synchronised to the length of each day and the passing of seasons. An accurate body clock can give it an edge over competitors, predators and pathogens.

“We were interested to see how plant circadian clocks would be affected in Sweden; a country that experiences extreme variations in daylight hours and climate. Understanding the genetics behind body clock variation and adaptation could help us breed more climate-resilient crops in other regions.”

The team studied the genes in 191 different varieties of Arabidopsis obtained from across the whole of Sweden. They were looking for tiny differences in genes between these plants which might explain the differences in circadian function.

Their analysis revealed that a single DNA base-pair change in a specific gene – COR28 – was more likely to be found in plants that flowered late and had a longer period length. COR28 is a known coordinator of flowering time, freezing tolerance and the circadian clock; all of which may influence local adaptation in Sweden.

“It’s amazing that just one base-pair change within the sequence of a single gene can influence how quickly the clock ticks,” explained Dr Rees.

The scientists also used a pioneering delayed fluorescence imaging method to screen plants with differently-tuned circadian clocks. They showed there was over 10 hours difference between the clocks of the earliest risers and latest phased plants – akin to the plants working opposite shift patterns. Both geography and the genetic ancestry of the plant appeared to have an influence.

“Arabidopsis thaliana is a model plant system,” said Dr Rees. “It was the first plant to have its genome sequenced and it’s been extensively studied in circadian biology, but this is the first time anyone has performed this type of association study to find the genes responsible for different clock types.

“Our findings highlight some interesting genes that might present targets for crop breeders, and provide a platform for future research. Our delayed fluorescence imaging system can be used on any green photosynthetic material, making it applicable to a wide range of plants. The next step will be to apply these findings to key agricultural crops, including brassicas and wheat.”

The results of the study have been published in the journal Plant, Cell and Environment.

###

Notes to editors
Please contact Greg Jones at the Earlham Institute with any media queries: Tel +44 (0)7792 154497 or [email protected]

Rees, H. et al, Naturally occurring circadian rhythm variation associated with clock gene loci in Swedish Arabidopsis accessions. Plant, Cell and Environment, 2020. DOI: 10.1111/pce.13941

The Earlham Institute (EI) is a world-leading research institute focusing on the development of genomics and computational biology. EI is based within the Norwich Research Park and is one of eight institutes that receive strategic funding from Biotechnology and Biological Science Research Council (BBSRC) – £5.43m in 2017/18 – as well as support from other research funders. EI operates a National Capability to promote the application of genomics and bioinformatics to advance bioscience research and innovation.

EI offers a state-of-the-art DNA sequencing facility, unique by its operation of multiple complementary technologies for data generation. The Institute is a UK hub for innovative bioinformatics through research, analysis and interpretation of multiple, complex data sets. It hosts one of the largest computing hardware facilities dedicated to life science research in Europe. It is also actively involved in developing novel platforms to provide access to computational tools and processing capacity for multiple academic and industrial users and promoting applications of computational bioscience. Additionally, the Institute offers a training programme through courses and workshops, as well as an outreach programme targeting key stakeholders and wider public audiences through dialogue and science communication activities.

earlham.ac.uk