How plants respond to heat stress, Study

A new study has found that to survive short periods of heat stress, plants activate a molecular pathway called the heat-shock response.

The research has been published in the 'EMBO Journal'.

This heat-shock response (common to all organisms) protects cells from damage inflicted by proteotoxic stress, which damages proteins. Such stress is not only caused by heat but can also result from exposure to certain toxins, UV light, or soil salinity.

The heat shock response protects cells in various ways, one of them being the production of so-called heat-shock proteins, which serve as molecular shields that protect proteins by preventing misfolding.

Plants respond to heat stress by activating heat shock factors and also other molecular players. In particular, hormones as chemical messengers are involved. Among the hormones that plants produce are brassinosteroids, which primarily regulate their growth and development.

But, in addition to their growth-promoting properties, brassinosteroids have other interesting abilities, one of them being their ability to increase the heat stress resistance of plants, and researchers at TUM have recently discovered what contributes to this protective ability.

Using the model plant Arabidopsis thaliana, a research group led by Prof. Brigitte Poppenberger was able to elucidate how a specific transcription factor - a special protein responsible for switching certain sections of the DNA on or off - is regulated by brassinosteroids. This transcription factor, called BES1, can interact with heat shock factors thereby allowing genetic information to be targeted towards the increased synthesis of heat shock proteins.

When BES1 activity was increased, plants became more resistant to heat stress, and when it is decreased, they became more sensitive to it. Furthermore, the group demonstrated that BES1 was activated by heat stress and that this activation is stimulated by brassinosteroids.

"These results are not only of interest to biologists trying to expand our understanding of the heat shock response but also have the potential for practical application in agriculture and horticulture," said Prof. Poppenberger.

Bio-stimulants containing brassinosteroids are available and can be tested for their ability to increase heat stress resistance in plants. Such substances are natural products that are approved for organic farming and thus could be used without problems.

Alternatively, BES1 may be an interesting target for breeding approaches. This could be used to create varieties that are more resistant to heat stress and thus provide more stable yields in the event of future heat waves.