At a Glance
- Three recent projects on the ISS National Lab demonstrate diverse applications for plant research in space.
- Through a collaboration with Budweiser, barley — the fourth largest cereal crop — seeds will be grown and studied on the ISS.
- The latest in a series of experiments from the University of Florida will further fundamental plant biology knowledge through imaging and molecular analysis.
- The Tomatosphere education program offers project-based learning opportunities for students throughout North America.
It doesn’t take a green thumb to know how dependent plants are on the Earth. Plants draw water and nutrients from the soil to grow and flourish. Even the act of “planting” involves digging a hole in the Earth’s surface and putting a seed in it. But, what would happen if you removed Earth from “planting”?
Using the International Space Station (ISS) U.S. National Laboratory, scientists are getting to the root of how the Earth’s gravity affects the way seeds germinate and plants grow. The research not only seeks to answer fundamental questions about plant biology but also help us better understand how to improve plant growth on Earth. This means paving the way for advances from determining how plants can grow in stressful environments to producing higher crop yields to even creating a tastier beer.
Building a Better Beer (and Beyond!)
As part of the SpaceX CRS-13 mission, an upcoming experiment will send barley (Hordeum vulgare) — an essential component of beer — to space. The experiment, a collaboration with Budweiser, will examine how the barley seeds are affected by life in space.
These seeds will spend 30 days onboard the ISS both being stored and germinating. On Earth, barley is stored in cool, dry places, and poor conditions can mean bad beer (yuck!). This experiment will first determine whether the ISS is a suitable environment to store barley seeds.
Then, it’s time to grow. Barley seeds will be grown in microgravity and given the same amounts of water and nutrients as on Earth. If the seeds grow as they do on the ground, they will reach 6 to 10 inches tall.
Microgravity conditions can be stressful for a growing plant, but so can conditions on Earth. Drought and temperature extremes challenge growing plants. For example, variations in the climate can cause the starch to protein ratio in barley to differ. Interestingly, some barley strains react differently to stress than others. Exposing barley to microgravity may reveal to scientists which genes are involved in allowing some variations of barley to survive in harsh conditions, giving insight into which varieties might be better suited to certain climates.
These experiments do more than just improve what’s in your glass. It also improves what’s on your plate.
Digging Deeper with Petri Plants
In addition to the potential commercial impacts, the ISS plant experiments offer the opportunity for a more basic understanding of plant biology. A series of experiments from the University of Florida have explored a fundamental question on how gravity affects the way roots oriented themselves downward.
Auxin, a plant hormone, was known to control the growth of roots in the downward direction. Through a process known as the “reverse fountain” model, auxin travels down the core of the root, to the root tip, and finally back up the outermost layer of root cells. Gravity was assumed to influence this process.
After spending some time onboard the ISS, the Arabidopsis thaliana (a model plant species) told a different story. Despite the near absence of gravity, auxin maintained the same reverse fountain model as seen on Earth. This means the way in which plant roots orient is not a function of gravity and instead an inherent feature of plant growth and development.
The series of experiments that revealed these conclusions were supported by both the ISS National Lab and NASA and included both the Characterizing Arabidopsis Root Attractions-1 (CARA-1, affectionately called “Petri Plants”) project and APEX03-2 (Advanced Plant EXperiments), which investigated plants of various ages and genetic backgrounds.
For these cutting-edge discoveries, repetition is key to drawing accurate scientific conclusions—ensuring that the results are consistent across flights. As such, another installment in this series of experiments will soon be making its way to the ISS on SpaceX CRS-13. CARA-2 will utilize advances in RNA isolation techniques to further explore gene expression in the samples. Additional Light Microcopy Module imaging will also take place to confirm the initial findings.
Both the CARA and APEX03-2 experiments used the Light Microcopy Module to visualize the distribution of auxin in the root tips. This method allows real-time analysis of live plants via a modified Leica RXA microscope, which can be operated by the ISS crew or by researchers on the ground. Upon return to Earth, preserved plants were also examined using confocal microscopy.
Experiments for Budding Scientists
Understanding the effects of microgravity on plants is not just for scientists. Since 2000 the STEM educational project, Tomatosphere, has allowed K-12 school children throughout North America to see the effects of microgravity on plants as well. Tomato seeds flown to the ISS and back (most recently on SpaceX-11) are provided to classes, allowing the students to take on the role of scientist, observing and qualifying the differences between space tomatoes and Earth tomatoes.
When a classroom participates they receive 30-35 seeds. The tomato experiment becomes a scientific quest. Just like scientist, students conduct a blind experiment, not knowing which seeds were space seeds and which were terrestrial. Tomatosphere offers not only a chance to understand plant biology and agriculture but also a means of understanding scientific principles: making predictions based on data, minimizing bias through controlled experiments, and collecting/recording data.
Over the course of several weeks, students observe the plants and take detailed reports of their growth patterns, noting differences in germination. Given their keen observations, students then can hypothesize which plant is from space. And, in the end they find out if their hypothesis was correct.
Tomatosphere has shown continued success, bringing experiments to a breadth of students: from summer camps, to homeschoolers, to Girl and Boy Scout troops. In 2017 alone, they reached more than 20,000 classrooms (that’s 500,000 students!).
With this success, comes potential. Future experiments from Tomatosphere are set to contain HOBO data loggers, measuring temperature, humidity and pressure. Additional plans include expanding the experiments to active research projects in which high school students can analyze molecular data postflight alongside collection of visual observations.
Seeding the Future
So, what are plants without Earth? Vital sources of knowledge and discovery. Advances in plant biology continue to flourish onboard the ISS, addressing persisting fundamental questions and supporting commercial and educational endeavors. Ultimately, sending plants to space betters the plants of Earth, and more importantly, helps the people who depend on them.