Polyethersulfone (PES) Membrane on Agar Plates as a Plant Growth Platform for Spaceflight

Plant biology experiments in microgravity face many challenges, among which are the constraints of the growth platforms available on the International Space Station (ISS). Protocols for preservation and sample return to Earth often limit efficient dissection of seedlings for downstream tissue-specific analysis. The Advanced Plant Experiment (APEx)-07 spaceflight experiment required a large quantity of dissectible, well-preserved seedlings suitable for omics analysis. During preflight tests, protocols were developed for using an agar-polyethersulfone (PES) membrane platform for seedling growth that allowed for seedling germination and growth aboard the ISS and rapid freezing to provide intact seedlings for dissection and extraction of high-quality DNA, RNA, and protein. Each component of the growth setup was carefully examined: membrane color, hydration and growth substrate, capacity for delayed germination, growth duration, harvest approach, and preservation pipelines were all individually optimized. Sterilized Arabidopsis seeds were adhered to PES membrane with guar gum. Membranes were laid onto 0.8% agar containing 0.5x Murashige and Skoog (MS) in 10 cm square Petri dishes and held at 4 °C until the experiment was actuated by placing the Petri dishes at room temperature. Seedlings were grown vertically for 12 days. PES membranes were removed from the agar, placed in the Petri dish lid, wrapped in foil, and frozen at −80 °C. Seedlings were dissected into roots and shoots and provided high-quality DNA, RNA, and protein. The system is simple, potentially adaptable for seedlings of multiple species, scalable and cost effective, and offers added versatility to existing ISS plant growth capabilities.