21 December 2018

Plant ‘remembers’ two environmental factors through accumulation of single protein

The same protein that keeps plants from blooming in winter also helps them survive during floods. In a recent article in Nature Communications, plant ecophysiologists at the universities of Utrecht, Birmingham, and Nottingham wrote about how the vernalisation protein VRN2 accumulates in plants both under low temperature conditions and as a result of a lack of oxygen during floods.

The plants’ ‘memory’ enables them to adapt their growth to changing environments or seasonal differences. Many perennial plants, for example, register the long period of colder weather during winter, and delay blooming until spring based on that observation. Scientists have known for some time that protein Vernalization2 (VRN2) exerts some influence on that process. Vernalisation is the biological term for how cold temperatures influence growth processes.

Memory protein

Now, researchers have found that VRN2 also plays a crucial role in registering a lack of oxygen, which is usually the result of flooding. Utrecht University PhD Candidate Sjon Hartman and his supervisor Rens Voesenek were surprised by the increased concentration of a single protein caused by at least two extremely different environmental factors. Hartman: “VRN2 is really a kind of ‘memory protein’, which makes plants flexible in a dynamic environment. After all, plants can’t just get up and leave when conditions get tough.”

In bloom mode

During their study, the researchers also discovered how VRN2 actually works. It is part of the protein complex PRC2, which was known to be the switch that activates the plant’s bloom mode, but scientists were unsure as to how. Now it seems to have everything to do with the stability of VRN2. Hartman: “Under normal conditions, VRN2 is extremely unstable and is constantly being broken down. But when temperatures or oxygen levels decrease, the protein becomes more stable and begins to accumulate in the plant’s cells, which in turn activates the entire PRC2 complex. One of the resulting effects includes delaying the plant’s bloom.”

Publication

Oxygen-dependent proteolysis regulates the stability of angiosperm Polycomb Repressive Complex 2 subunit VERNALIZATION2

Daniel J. Gibbs, …, Sjon Hartman*, Laurentius A.C.J. Voesenek*, … en Michael J. Holdsworth.

*Affiliated with Utrecht University.

Nature Communications 9, 21 december 2018