A team of researchers from the United Kingdom and the Netherlands has identified a mechanism that enables angiosperms (flowering plants) to sense and remember changes in their environment.
Histochemical staining of Arabidopsis thaliana: (i) 7-day-old seedling primary root tip, (ii) rosette leaf, (iii) cauline leaf and (iv) inflorescence of Col-0 and prt6-1 lines expressing wild type VRN2-GUS. Scale bar in (i) – 500 μm. Image credit: Gibbs et al, doi: 10.1038/s41467-018-07875-7.
Plants’ memory function enables them to accurately coordinate their development in response to stress or to the changing seasons.
For example, many plants remember the extended cold of winter, which ensures that they only flower in spring when warmer temperatures return.
One way they do this is through a group of proteins called PRC2 (polycomb repressive complex 2).
In the cold these proteins come together as a complex and switch the plant into flowering mode.
Little is known about how PRC2 detects environmental change to make sure it is only active when needed.
The new study, led by scientists from the Universities of Birmingham and Nottingham, provides new insight into the ‘environment sensing’ function of PRC2.
The researchers discovered that a core component of the complex — a protein called VRN2 (polycomb group protein VERNALIZATION 2) — is extremely unstable.
In warmer temperatures and when oxygen is plentiful, VRN2 protein continually breaks down.
When environmental conditions become more challenging, for example when a plant is flooded and oxygen is low, VRN2 becomes stable and enhances survival.
VRN2 protein also accumulates in the cold. This allows the PRC2 complex to trigger flowering once temperatures rise.
The study authors investigated the reasons for this and found a surprising similarity between plant responses to cold and low oxygen experienced during flooding.
“Plants have a remarkable ability to sense and remember changes in their environment, which allows them to control their life cycle,” said study co-lead author Dr. Daniel Gibbs, a researcher in the School of Biosciences at the University of Birmingham.
“VRN2 is continually being broken down when it is not needed, but accumulates under the right environmental conditions. In this way, VRN2 directly senses and responds to signals from the environment, and the PRC2 remains inactive until required.”
“It is possible that this mechanism could be targeted to help create plants that are better adapted to different environmental scenarios, which will be important in the face of climate change.”
“Interestingly, animals also have the PRC2 complex, but do not have an unstable VRN2 protein,” said study co-lead author Professor Michael Holdsworth, from the University of Nottingham.
“This system appears to have evolved specifically in flowering plants. Perhaps it gives them more flexibility in their ability to adapt and respond to environmental change, which is important since they are fixed in the ground and can’t move.”
The research is published in the journal Nature Communications.
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Daniel J. Gibbs et al. 2018. Oxygen-dependent proteolysis regulates the stability of angiosperm polycomb repressive complex 2 subunit VERNALIZATION 2. Nature Communications 9, article number: 5438; doi: 10.1038/s41467-018-07875-7
