Apparently not synchronised
In spring all plants of the same species appear to flower at the same time. Their age apparently does not matter. Now American researchers show that age may indeed have a role.
Synchronised flowering of plants is the source of exuberant floral splendour. At the same time it helps with the pollination of the flowers. To make sure that their flowering is in step with that of others of their species plants use many environmental factors. Like temperature and daylength. But the age of the plant also plays a role. As for success a plant needs to flower before it dies.
The researchers decided to study to what effect age plays a role in flowering time. This they did using plants that need a cold period before they can flower. In addition they kept all other environment factors constant so that they did influence on the outcome. In comparison with plants that did not need a cold period to flower, the flowering of plants that did require a cold period appeared to be more synchronized.
With the emphasis on appeared. Closer analysis made clear that also plants that need a cold period flower asynchronous. Plants that germinated well before the cold period started flowered sooner after the cold period than plants that had just germinated at the start of the cold period. Although those last ones were younger when flowering.
The rate of FT activation appears to be correlated with the age of the leaf
To find an explanation the researchers studied how strongly the flowering-gene FT and the FT repressing gene FLC were turned on in the different leaves of the plant. FT appeared to be strongly expressed in leaves that grew during and after the cold period, but was hardly expressed in leaves that were present before the cold period started. In contrast FLC was strongly expressed in leaves that grew before the cold period, but less in leaves that grew during the cold period, and mostly turned off in leaves that grew after the cold period.
FT was not turned on at the same rate as FLC was turned off. From this it appears that during the cold period FT is not losing its repression by FLC but probably also activated by an unknown factor. The amount of activation appears to correlated with the age of the leaf that the researchers were studying.
All together a lot of assumptions. But enough to be able to say that there are other factors, in addition to a cold period, that determine when a plant flowers. One of the factors that the researchers like to study in more detail is age.
Literature
Huang, P.-K., Schmitt, J. and Runcie, D.E. (2024), Exploring the molecular regulation of vernalization-induced flowering synchrony in Arabidopsis. New Phytol. https://doi.org/10.1111/nph.19680
Plant en Zo 