Let’s Grow Beans in Space!

Although they seem like normal, everyday plants, beans have a hidden superpower that could make them indispensable crops for spaceflight.

credit: Kien Cuong Bui

What makes them special?

Beans, peas, and the other members of the family Fabaceae are called legumes, and many legumes are able to do something that other plants can’t: they can make root nodules. Essentially, root nodules form when root cells send out chemical signals to attract bacteria, the bacteria enter the root cells, and the root forms a special “nodule” of root tissue around the bacteria. The root nodule provides everything the bacteria need to survive (like oxygen and sugar), and in return the bacteria produce nitrogenase, a form of nitrogen that plants can absorb. Nitrogen is abundant in the air, but most organisms cannot use it in this gaseous form—only nitrogen-fixing organisms like these bacteria can fix nitrogen into an organic form that other organisms (like plants and animals) can use. Nitrogen is one of the primary nutrients that all organisms need to survive, and is a key component of fertilizers. Legumes don’t need to be fertilized with nitrogen as often as non-legumes, which could make legumes even more useful as space crops.

Legumes in Space

Although legumes are vital to global agriculture, we’ve only grown legumes in space a handful of times. Around 1980, pea seedlings were grown in the Oasis 1AM to study the organelles in the meristem and root cap. Between 2003 and 2005, Russian cosmonauts grew pea plants in LADA to study pea growth, development, and genetic status in space. Astronauts grew soybean briefly in the ADVASC, and lentils in the EMCS. Several other studies have examined legume seeds that were sent into space but were germinated back on Earth.

Unfortunately, none of these experiments examined root nodulation in space. This is a problem because the astronauts and plants on long-duration missions will need nitrogen to survive, and chemical nitrogen fixation is too energy-intensive to be feasible. Mining minerals from the Moon and Mars wouldn’t solve this problem either—we’ve found all essential minerals for plants in lunar and martian soils except reactive nitrogen. In order to address the gap in legume research, a group called Magnitude.io is planning to send a legume to space, with the help of school-age children across the world. They will send their space plant growth chamber, ExoLab-8, to the ISS in February of 2021, and k-12 classrooms across the world are conducting their own ground trials to prepare for the mission. Not only is Magnitude.io preparing to address the gap in legume research, but they’re also helping children learn about astrobotany and contribute to real-life research.

A few previous studies indicate that nitrogen-fixing bacteria can bind to roots and start developing nodules in microgravity, so legumes will probably be able to develop nodules next February. But until we see the results of Magnitude.io’s experiment, many questions will remain unanswered. Please keep your eye out in spring of 2021 to learn the results of this research! Studying legume root nodules on the ISS will bring us a few steps closer to the next goalpost: growing enough food crops to feed astronauts on the journey to Mars.

Let’s grow beans in space!

References