Entanglement of Arabidopsis Seedlings to a Mesh Substrate under Microgravity Conditions in KIBO on the ISS.

The International Space Station (ISS) provides a precious opportunity to study plant growth and development under microgravity (micro- G ) conditions. In this study, four lines of Arabidopsis seeds (wild type, wild-type MCA1-GFP, mca1 -knockout, and MCA1 -overexpressed) were cultured on a nylon lace mesh placed on Gelrite-solidified MS-medium in the Japanese experiment module KIBO on the ISS, and the entanglement of roots with the mesh was examined under micro- G and 1- G conditions. We found that root entanglement with the mesh was enhanced, and root coiling was induced under the micro- G condition. This behavior was less pronounced in mca1 -knockout seedlings, although MCA1-GFP distribution at the root tip of the seedlings was nearly the same in micro- G -grown seedlings and the ground control seedlings. Possible involvement of MCA1 in the root entanglement is discussed.