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What plant genes can teach us

Just like us, plants also produce growth hormones, and they also go through an ageing process. The study of the genes and mechanisms behind these processes is useful not only for crop breeding and agriculture, but also for medical research. That is the view held by Professor of Plant Developmental Genetics Remko Offringa. Inaugural lecture on 16 March.

Plants are remarkable organisms, according to Remko Offringa: they can direct their own growth and development. Researchers, breeders and growers all try to influence these processes to ensure that we have enough – especially healthy – food, or to allow us to decorate our homes with colourful flowers. Offringa studies which genetic characteristics are important for plants’ growth and development. That knowledge will eventually make it possible to breed plants that yield more crops, in an environmentally conscious way. As well as its agricultural applications, this research is also producing fundamental new insights which can be used in industrial biotechnology or medical science.

Growth hormones in plants

One of the important substances Offringa studies is auxine, the key growth hormone in plants. It was the first hormone to be discovered in plants, partly thanks to experiments carried out by Charles Darwin. During his research into natural selection, Darwin was interested in how plants move, for example under the influence of gravity and the sun, and how this helps them to adapt to their environment. Darwin studied how canary grass seedlings lean towards the light, and discovered that this was due to the cells on the dark side stretching more than the cells on the light side. He worked out that there must be a substance which sends a signal down the plant from the top of the seedling. More than 40 years later, auxine was found to be the substance responsible for sending this signal.

Adapting to the environment

Finding out how auxine works will benefit farmers and growers. Taking thale cress (Arabidopsis thaliana) as a model, Offringa’s colleagues are currently investigating how factors such as light or the availability of nutrients affect certain molecules within the plant which direct the way in which auxine is distributed. The plant uses these mechanisms to adapt its structure to its environment and growing conditions.

Two thale cress plants. The plant on the right displays an enhanced expression of the REJUVENATOR gene, which causes the plant to grow more.
Two thale cress plants. The plant on the right displays an enhanced expression of the REJUVENATOR gene, which causes the plant to grow more.

Combating ageing

Auxine also directs the ‘REJUVENATOR’ gene, which plays an important role in a young plant’s development. When this gene is stimulated more than usual, cells in the adult plant can be restored to a stage of life one or two stages earlier. This gives the cells a kind of genetic reset – hence the name – which enables thale cress plants to live longer, flower more often and produce more biomass and seeds. Another surprising discovery was that REJUVENATOR also suppresses photosynthesis, and thereby also the production of sugars. In plants, sugars accelerate the transitions between the different life stages, which also speeds up the ageing process. Sustained high blood sugar levels also cause cells to age more quickly in humans, which leads Offringa to propose that, through research into the REJUVENATOR gene, we can learn a lot about our own ageing process. Knowing how the gene brings about a genetic reset is also useful for research into human stem cells: plant genes can teach us a lot about ourselves.