Giving Plants Superpowers: A Conversation with Gözde Demirer

Gözde Demirer wants to give plants superpowers—the ability to sustainably feed the world, or to handle drought and climate change, for example—and to do it all while improving the health of the environment. A mask and cape won't do. Instead, she uses the tools of nanotechnology, synthetic biology, and genetic engineering, and leverages the help of plants' trusty sidekicks: beneficial microbes in the soil.

Demirer is the Clare Boothe Luce Assistant Professor of Chemical Engineering at Caltech. Her work focuses on three main areas: developing nanoparticles that can efficiently deliver biomolecule cargoes into plants, making genetic engineering tools more effective and precise in plants, and figuring out ways to harness beneficial interactions between plants and the microbes that live in and around them.

Demirer was born and raised in Istanbul, Turkey, where she earned her undergraduate degree in chemical and biological engineering at Koç University. She completed her graduate training in chemical and biomolecular engineering at UC Berkeley in 2020 and at that time was offered a faculty position at Caltech. She opted to complete a postdoctoral position at the UC Davis Department of Plant Biology before joining the Caltech faculty in 2022.

We sat down with Demirer to learn more about the roundabout way she came to her specialty and some of the possibilities she envisions for plants with superpowers.

Can you please give us a broad overview of your group's work?

We develop creative synthetic biology and nanotechnology tools to be able to precisely manipulate plants and their microbiomes to improve plant health. We would like to increase plant production and resilience by improving plant genes and genomes using new genetic-engineering techniques so that they are more suitable for growth under the changing climate.

At the same time, we are interested in improving environmental health. Current agricultural practices involve the use of excess chemical fertilizers and pesticides, which results in eutrophication, soil degradation, greenhouse gas emissions coming from agricultural fields, and loss of biodiversity. That means that agriculture is a big contributor to human-caused climate change. We try to improve plants such that we can grow them without harming the environment using less agrochemicals and natural resources. For example, we are interested in taking advantage of beneficial microbes, instead of using synthetic fertilizers, to fix soil nutrients or get them into a form that plants can use.

You mentioned genetic-engineering techniques. Can you please talk about how you use that in your work with plants?

One of the genetic-engineering capabilities that we have been focusing on recently is the ability to insert a specific gene into a targeted location within a plant genome, which has many powerful uses in fundamental plant biology and also biotechnology applications. We are working to develop gene-editing machinery that can do that. Much of this machinery has originated in bacteria and has been engineered to work well in mammalian cells. However, by design, they don't work well in plants. The simplest example is that the CRISPR molecules are optimized to work in the human body at 37 degrees Celsius [98.6 degrees Fahrenheit] while plants exist at room temperature, maybe 20 degrees [68 degrees Fahrenheit]. In transferring from the human body to plants, the enzymes lose most of their efficiency simply because of that temperature decrease. But there are many other reasons why these molecules are less efficient in plants. These molecules work with bacterial proteins, bacterial genomes, and when we put them into plants, it's a completely different genome architecture—different proteins, different genes. And they're not very efficient. So, in one approach, we engineer genetic engineering machinery in a way that they will function better specifically in plant cells. And in another approach, we try to discover genetic engineering machinery from eukaryotic organisms that may be easier and more efficient to translate to plants.

How did you end up working in plant genetic engineering?

My background as an undergraduate researcher was in developing nanomaterials for drug delivery into human systems. I was working with cancer and diabetes. I thought that I would probably stay in similar fields.

But when I started considering labs as a grad student at UC Berkeley, there was a principal investigator who was just getting started, Markita Landry. She had been working with nanoparticles that her lab wanted to use as sensors of neurotransmitter release in the brain. They would release them into the area between the cells in the brain, but instead of staying there, the nanoparticles actually entered the neuronal cells. These cells are very hard to deliver anything into, so Markita started to think the nanoparticles could be useful for delivering to cells that are hard to get into, and we realized that plant cells are also very challenging to deliver genes or small molecules into, given their rigid cell wall. We got very excited about the impact that nanoparticles could have in plant biology and bioengineering. Neither of us had a background in plant biology, so we started together from scratch!

What was it like going back to learn something entirely new?

Initially, it was a lot to learn. Luckily, we had collaborators who were plant biologists who got us started. Later, I decided to do a postdoc at UC Davis where there is a lot of plant biology expertise. It was very helpful to learn from people who have been working with actual crops and who've been engineering plant genes and genomes.

Wow! So that conversation with Dr. Landry has turned into the focus of your lab?

Well, we do a lot of work on delivery into plants and on improving genetic engineering, but we also focus on the fundamental understanding of how these processes are controlled in plants.

In plants, we often don't know which genes are responsible for which function. For example, if we want to make plants drought resilient, we don't know which gene to edit. Even if we have the best tools to deliver cargo and to do genetic engineering, we also need to know which genes to change so that the plants become more resilient. So, we also do some of that work, trying to understand plant gene functions and how they are regulated so that whatever we end up doing in the lab will also be applicable in the field.

We are also very interested in plant-microbe interactions. Microbes do a lot to keep the soil around plants healthy, and we are not really taking advantage of that. My lab is trying to understand how we can enrich beneficial bacteria in the soil microbiome. This could be very useful when there's a nutrient deprivation, for example.

Manipulating the plant microbiome is an area I started working on when I came to Caltech. The first thing we are trying to do is to find the chemical communication molecules that plants use to "talk" with microbes. These are not well known. We don't know exactly what comes from a plant to a microbe that causes microbes to cluster around the plant's roots. We know that carbon substrates and chemoattractants are involved. We are figuring out now that each type of bacteria likes a different type of carbon. And if you change what type of carbon comes from a plant, you can also control what type of microbes are in the soil.

We usually ask faculty members about their hobbies and other interests. Do you have any?

I like a lot of outdoor activities. I try to go out hiking, biking, exercising, seeing new places. In my job, I do a lot of sitting, so I like to do something that gets me moving.