The molecule cAMP, which plays essential roles in mammalian cells, is less well understood in plants. In a new Science Advances paper , researchers from the Institute of Science and Technology Austria (ISTA) and international collaborators demonstrate that plants use two forms of cAMP in parallel to regulate normal cellular processes and respond to stress, while maintaining crosstalk between them. That crosstalk provides redundancy, so that if one fails, the other can compensate, allowing plants to respond more robustly to a wider range of environmental factors. Ultimately, the findings could help improve crop resilience and productivity in a rapidly changing climate.
Plants can't escape danger. To cope with stresses such as heat, freezing, flooding, drought, or infection, they rely on biological mechanisms evolved over millions of years.
Different life forms face unique environmental challenges, driving them to evolve distinct biological processes. Although animals, plants, and microbes share many molecular mechanisms, insights from animal models often don't apply directly to other kingdoms.
Cyclic adenosine monophosphate, also known as cAMP , is a fundamental signaling molecule known to play essential roles in both animal and plant cells. However, although its production and role in mammalian cells are well understood, its functions in plants remain largely unknown.
Now, ISTA alum Mingyue Li and professor Jiří Friml at the Institute of Science and Technology Austria (ISTA) have teamed up with scientists in Germany, Saudi Arabia, the Czech Republic, and the United States to shed light on cAMP in the plant model Arabidopsis thaliana, commonly known as mouse ear cress or thale cress.
Twin molecules with distinct but partially overlapping properties
In animal systems, the main form of cAMP, called 3',5'-cAMP, is involved in the transfer of signals between nerve cells, hormone signaling, and the regulation of metabolic functions. This predominant form of cAMP is derived from the cell's energy currency, ATP. However, cAMP has a 'twin' form: a molecule with the same chemical formula but different atomic bonds. Concretely, the phosphate group is attached to the adenosine molecule at a different location. This other form, called 2',3'-cAMP, is associated with RNA degradation and stress response. Its levels are tightly controlled in mammalian cells because excessive amounts can be toxic.
Li, Friml, and their colleagues now show that, while both forms of cAMP exist in plants, the levels of 2',3'-cAMP—the 'other' form of the molecule—are over 60 times higher than those of 3',5'-cAMP, the main form found in animals.
Using a battery of molecular and cell biology techniques, the team demonstrates that the two forms of cAMP exhibit largely distinct functions in plant metabolism as well as in protein and gene regulation. While 3',5'-cAMP appears to fine-tune responses related to growth, maintenance, nutrient status, and normal cell function, 2',3'-cAMP triggers much broader effects in plants, including specialized metabolic pathways and broad stress responses. However, they also show that these functions partially overlap, suggesting that plants may have evolved distinct ways to adapt to environmental challenges.
Cross-talking signaling pathways
Maintaining two parallel but interconnected cAMP pathways could help plants fine-tune cellular regulation and distinguish among different external stimuli, including stress factors. Crosstalk between the pathways provides redundancy, so that if one fails, the other can compensate, allowing plants to respond more robustly to a wider range of environmental factors.
Ultimately, understanding how plants regulate stress and routine cellular functions could help boost crop productivity and enhance resilience to climate change.
