In April 2020, we mark both the 50th celebration of Earth Day on April 22, and DNA Day on April 25. As both Earth and DNA are close to our JGI hearts, we’re highlighting genomic science research that feels especially relevant to living on a changing planet.
Transcript for Audio
ALISON: Hey! I’m Alison Takemura at the US Department of Energy Joint Genome Institute, or JGI.
Two special days occur in April: the 50th celebration of Earth Day on April 22, and DNA Day on April 25. Since both DNA and the Earth are close to our JGI hearts, we’re featuring some scintillating genomic science research that feels especially relevant to living on a changing planet.
In this short audio production, we’ll hear from Karolina Heyduk, an evolutionary plant biologist at the University of Hawai’i at Mānoa. I recently caught up with Karolina at the Plant and Animal Genomes, or PAG conference, when in-person meetings were still a thing, i.e. in January. She talked about her Community Science Project proposal with JGI, in which she’s studying a special kind of plant metabolism. This metabolism, called crassulacean acid metabolism, or CAM — that’s C-A-M, for short — helps plants that have it lose less water in a hot, dry environment. Figuring out how plants evolved to deal with hot and dry conditions could help us to one day develop plants that are more drought-tolerant. These kinds of innovations are particularly relevant as climate change intensifies and accelerates drought and desertification across the globe.
Karolina and I kicked off our conversation with a quick recap of how plants, in general, work.
KAROLINA: We all know plants take up water through their roots. But for them to be able to pull that water through the whole plant system, they need to open these pores in their leaves called stomata. And through those pores, water is moved into the atmosphere basically along its concentration gradient. So the movement of water through stomata is really important. And when those stomata are open, it’s the same pore in the leaf through which carbon dioxide enters the leaf for photosynthesis.
ALISON: Photosynthesis is what allows plants to make their own food from light and air – in particular, the part of the air that’s carbon dioxide.
KAROLINA: When plants get really hot or dry, they want to close those stomata to prevent water loss, but that also prevents CO2 from coming into the leaf and it basically starves the plants.
ALISON: That’s what might happen for a stressed typical plant, one that does what’s called C3 metabolism, named for a 3-carbon compound that plays an essential role. But other plants, which do CAM, can kind of clam up during the day, and open their stomata at night to absorb CO2 when it’s cooler. That way, they don’t lose all their water AND they still get the carbon dioxide they need.
Karolina is working to better understand what genetic features make CAM possible. So, she’s studying yuccas, a group of plants in the Agave family with fleshy, sword-like leaves, often with spikes along their edges.
KAROLINA: My work with the JGI focuses on a group of plants called yuccas. If you know Joshua Tree, that’s an example of a yucca species. And the cool thing about yuccas is that there are closely related species that use C3 and CAM.
ALISON: But plants don’t need to be restricted to either CAM or C3 metabolism. Karolina says plants can be somewhere in between.
KAROLINA: Plants can use a little bit of both pathways. Some plants can appear to be almost entirely C3, and then when they get drought stressed, they can up regulate that CAM. There are all sorts of other intermediate phenotypes where plants are using a little bit of both of the pathways.
ALISON: Karolina studies these CAM-C3 hybrids.
KAROLINA: Some of these hybrid genotypes that I look at can preferentially up-regulate CAM when they’re drought stressed, whereas others don’t seem to be able to. So it allows us to be able to tease apart some of the mechanisms that regulate that response to drought through CAM.
ALISON: We’ll hear more about CAM and Karolina’s quest in a future episode of our JGI podcast, Genome Insider.
I’m Alison Takemura. See you next time.