Climate change is altering the genetic programming of plants

Plants and other organisms can physiologically adapt to changing environmental conditions, but this ability has its limitations. In a new study from the University of Würzburg, researchers have investigated why plants often malfunction when exposed to extreme conditions. 

The leaves of a dandelion are much smaller in sunny locations where less leaf area is needed to adequately support photosynthesis. This is an example of a plant’s genetic programming.

However, under persistent heat stress, dandelions may deviate from their normal programming. As a result, they can develop a wide range of unnatural leaf shapes in a response that is referred to as a “hidden reaction norm.”

“Organisms withstand normal ranges of environmental fluctuations by producing a set of phenotypes genetically programmed as a reaction norm; however, extreme conditions can expose a misregulation of phenotypes called a hidden reaction norm,” explained the researchers.

“Although an environment consists of multiple factors, how combinations of these factors influence a reaction norm is not well understood.”

Prior to this study, the exact cause of hidden reaction norms has been largely unknown. But as Earth’s climate continues to shift, it is more important than ever before to understand what triggers such abnormalities.

The investigation was focused on a variety of malformed leaves that sometimes develop in the carnivorous Australian pitcher plant Cephalotus follicularis. In an effort to pinpoint the cause of hidden reaction norms, the researchers exposed the plants to different conditions for twelve weeks in growth chambers.

“The hidden reaction norms of this plant could be revealed when uncommon combinations of benign or neutral environmental stimuli prevail,” said Dr. Kenji Fukushima. This causes the plant to deviate from its normal programming, forming either flat, photosynthetically active leaves or leaves that are transformed into insect traps.

When plants were exposed to summer temperatures with fewer daylight hours, they increasingly formed misregulated leave phenotypes. These are the precise conditions that are becoming more common in many regions of the world due to climate change – hotter temperatures on spring and autumn days with less daylight. 

“Our results suggest that even if individual cues are within the range of natural fluctuations, a hidden reaction norm can be exposed under their discordant combinations,” concluded the researchers.

“We anticipate that climate change may challenge organismal responses through not only extreme cues but also through uncommon combinations of benign cues.”

The study is published in the journal Proceedings of the Royal Society B.

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By Chrissy Sexton, Earth.com Staff Writer