New Biosensor Could be Key to Timing Fruit Ripening

A new biosensor targeting ethylene, a fruit ripening hormone, is shedding light on how ethylene impacts plants not only during ripening but also in processes such as seed germination and pathogen defense. The innovative technique has the potential to extend the shelf life of produce, find better solutions for combating some plant diseases and develop more resilient plant varieties.

“The goal of this project was to develop a biosensor for visualizing when and where ethylene functions in plants, at what point it’s activated and in which tissues it is active,” says Anna Stepanova, a professor in the Department of Plant and Microbial Biology at NC State University and corresponding author of a paper describing the research.

The biosensor uses a specifically engineered plant line that can detect the presence of ethylene. Areas of the plant where ethylene is present glow through the use of a fluorescent protein gene or stain blue through the use of an enzyme gene.

“Whichever parts of the plant express these engineered ‘reporter’ genes in response to ethylene, those parts of the plant will glow in the dark or turn blue,” Stepanova says. “This allows us to see by the naked eye or with magnification by microscopy which cells in what conditions respond to the plant hormone ethylene.”

Collaborator Jose Alonso, William Neal Reynolds Distinguished Professor and University Faculty Scholar in plant and microbial biology, says the new tool opens the door for researchers to better understand the hormone’s role not only in ripening but also in a plant’s response to pathogens, nodulation, and relationships between ethylene and parasitic plants. The technology used to develop this biosensor could also potentially be used to adjust the timing of ripening in fruit.

“When the fruit starts ripening, it produces more ethylene,” Alonso says. “So you could take this [biosensor], fuse it to a gene that inhibits ripening, so that now when you have more ethylene you actually can reduce the speed of ripening.”

Anna Yaschenko, a doctoral candidate in plant biology, co-authored the paper, published in the Plant Biotechnology Journal, with former NC State postdoctoral research scholars Josefina-Patricia Fernandez-Moreno and Mario Fenech. The research gave Yaschenko hands-on experience with applying various scientific techniques, including testing the biosensor’s response in the plant Arabidopsis under different conditions. Researchers also tested the biosensor in tomato plants.

“I was looking to see where the blue was when I was staining them, specifically which tissues of the plants would light up under different ethylene conditions,” Yaschenko says. “I also characterized some of the fluorescent lines to make sure we had a full set of all the transgenic plants that we had generated.”

The research extended Yaschenko’s synthetic biology research into a real-world experiment.

“This was kind of the real-life application of what I am studying, of how to optimize [biosensors] in order to get expected levels of expression of genes or hormones,” Yaschkeno says.

Stepanova says ongoing collaborative work with international researchers now aims to leverage the biosensor’s DNA elements to create biosensors that are compatible with one another to monitor multiple hormones simultaneously to understand how they interact in processes like plant growth, heat stress, infections and more.

“One of our ultimate goals is to try to reduce food waste because we lose a lot of fruits and vegetables due to overripening and senescence (the deterioration of plants over time),” Stepanova says. “Both of these processes are controlled by ethylene so we hope that our tool will help us identify conditions or treatments or genotypes that are better at postharvest storage.”

This post was originally published in College of Agriculture and Life Sciences News.