Study reveals key process by which plants switch between different stress responses

To design effective strategies that protect significant agricultural crops from climate change, it is important to understand how plants react to stressful environmental conditions.

Photo of flowering Arabidopsis thaliana. Image Credit: Shutterstock.

A new study, headed by Zhiyong Wang, Shouling, Xu, and Yang Bi from the Carnegie Institution for Science, shows a crucial process through which plants change between dampened and intensified stress reactions. The researchers’ study has been published by the Nature Communications journal.

Plants must select between various response strategies to survive in a variable environment, and these strategies are based on external environmental conditions as well as internal energy and nutritional demands. For instance, a plant may either speed up or delay its lifecycle, based on the availability of stored sugars that constitute its energy supply.

We know plants are able to modulate their response to environmental stresses based on whether or not nutrients are available. But the molecular mechanisms by which they accomplish this fine tuning are poorly understood.”

Zhiyong Wang, Department of Plant Biology, Carnegie Institution for Science

For many years, plant biologists from the Carnegie Institution for Science have been designing a treasure trove of studies on a system through which plants detect the available nutrients. A sugar molecule is the one that gets attached to proteins and modifies their behavior. Dubbed O-linked N-acetylglucosamine, or O-GlcNAc, this sugar tag is linked to changes in cell growth, gene expression, and cell differentiation in both plants and animals.

O-GlcNAc functions have been extensively studied in the context of various human disorders, like neurodegeneration, cancer, and obesity, but are relatively less understood in plants. Then in 2017, the Carnegie-led research team became the first to detect scores of plant proteins altered by O-GlcNAc, offering a basis to completely evaluate the nutrient-sensing network regulated by it.

In this latest analysis, the research team from Wang’s laboratory, which included lead authors Bi, Zhiping Deng, Dasha Savage, Thomas Hartwig, and Sunita Patil, and Xu’s laboratory which included Ruben Shrestha and Su Hyun Hong, demonstrated that one of the proteins altered by the O-GlcNAc tag offers a cellular physiological connection between stress response and sugar availability.

Apoptotic Chromatin Condensation Inducer in the Nucleus, or Acinus for short, is an evolutionarily conserved protein that is known to play various roles in the processing and storage of cell’s genetic material in mammals.

Through an extensive series of proteomic, genomic, and genetic experiments, the research team from the Carnegie Institution for Science has shown that in the case of plants, Acinus creates a protein complex that is similar to its mammalian equivalent and plays a special role in controlling stress reactions as well as the crucial developmental changes, like seed germination and flowering.

The study also revealed that the sugar alteration of the Acinus protein enables the availability of nutrients to modulate the sensitivity of a plant to environmental stress and to regulate the time for seed germination and flowering.

Our research illustrates how plants use the sugar sensing mechanisms to fine tune stress responses. Our findings suggest that plants choose different stress response strategies based on nutrient availability to maximize their survival in different stress conditions.”

Shouling Xu, Department of Plant Biology, Carnegie Institution for Science

Looking ahead, the team wants to examine additional proteins that are tagged by O-GlcNAc to find out how this essential system could be used to combat hunger.

Understanding how plants make cellular decisions by integrating environmental and internal information is important for improving plant resilience and productivity in a changing climate. Considering that many parts of the molecular circuit are conserved in plant and human cells, our research findings can lead to improvement of not only agriculture and ecosystems, but also of human health.”

Zhiyong Wang, Department of Plant Biology, Carnegie Institution for Science