Signals from the roots: how the plant hormone cytokinin influences flowering

Isabel Bartrina uses thale cress (Arabidopsis thaliana) as a model for her research. Photo: University of Graz / Pichler

Many do it in spring, others wait a little longer and some really get going in winter – when a plant begins to flower is controlled by various internal and external signals. In a study published in the renowned scientific journal Plant Physiology, researchers at the University of Graz were able to clarify the role played by the hormone cytokinin in this process. The findings are also interesting with regard to the breeding of crops for agriculture. In view of changing climatic conditions, adjustments to the start of flowering could help to secure yields.

The growth cycle of plants is influenced by a number of external conditions, above all temperature and sunlight. However, there are also internal controlling factors. These include the plant hormone cytokinin. “Cytokinin promotes flowering in both long and short days, with a particularly strong effect when there are only a few hours of daylight,” reports Isabel Bartrina, first and corresponding author of a current publication on this topic.

The plant physiologist from Tomáš Werner's research group at the University of Graz has investigated how cytokinin regulates flowering. “The strongest influence is exerted by specific forms of the hormone that are produced in the root: the so-called trans-zeatin,” says Bartrina. “If its transport is disrupted, flowering is delayed. These results reveal a surprising and hitherto little-noticed role of the roots in flowering induction.”

Cytokinin influences the levels of the microRNA molecules miR156 and miR172, which regulate the ageing process. “The higher the cytokinin level, the faster the plant matures, so to speak. Only when it has reached this stage can it flower,” explains the researcher. If the hormone is missing, flowering is delayed. The scientists used thale cress (Arabidopsis thaliana) as a model for their investigations.

The new findings could be used to breed crops whose flowering time needs to be adapted to climatic conditions or other requirements. This could be to avoid damage from late frosts or to ensure optimal pollination by bees.

Publication
Root-derived cytokinin regulates Arabidopsis thaliana flowering time through components of the age pathway
Plant Physiology
https://doi.org/10.1093/plphys/kiaf204

⇒ If you want to find out more about the inner life of plants and their secrets of success, you can study Biology at the University of Graz

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