Advanced Plant Experiment-10 (APEX-10)

Plant and microbial associations are key to the success of individual plants, but scientists do not yet understand how the space environment may alter these associations. Plant-Microbe Interactions in Space (APEX-10) tests whether the beneficial microbe Trichoderma harzianum confers increased stress resilience and improved growth to seedlings of tomato plants (Lycopersicum esculentum) when the two are grown together in microgravity.

Experiment launched to the International Space Station (ISS) on the NG-20 Commercial Resupply Service mission in January, 2024.

Plants and microbes form intimate associations that are key determinants of an individual plant’s success. An important gap in the understanding of plant growth in spaceflight is how exposure to the space environment may alter these associations. The Plant-Microbe Interactions in Space (APEX-10) investigation focuses on testing the hypothesis that the beneficial microbe Trichoderma harzianum confers increased stress resilience and improved growth in tomato seedlings (Lycopersicum esculentum) when grown together in microgravity on the International Space Station.

Following sample return, a combination of RNAseq, growth analysis, 13C isotopic analysis (to monitor photosynthetic water use efficiency), glycomics (to monitor alterations in cell wall composition), and ionomics (to monitor nutrient uptake and distribution) are used to gain a greater understanding of how plants and microbes respond to spaceflight and how this environment may affect their interactions. In addition, this research addresses the practical hypothesis that some of the deleterious effects of spaceflight on plant growth and development can be mitigated by interactions with defined beneficial microbes.

APEX-10 examines whether beneficial microbes can mitigate some of the negative effects of spaceflight on plant growth and development. Results could provide insight into how plant-microbe interactions are affected by spaceflight and specifically whether T. harzianum could serve as a biostimulant to counteract some of the stresses of spaceflight on plant growth.

This project could help provide insight into plant-microbe interactions, especially those between T. harzianum and plant roots. This insight may support steps to optimize these beneficial interactions to increase plant productivity on Earth as well as in space.