Transgene expression patterns indicate that spaceflight affects stress signal perception and transduction in Arabidopsis

The use of plants as integral components of life support systems remains a cornerstone of strategies for long-term human habitation of space and extra terrestrial colonization. Spaceflight experiments over the past few decades have refined the hardware required to grow plants in low-earth orbit and h ave illuminated fundamental issues regarding spaceflight effects on plant g rowth and development. Potential incipient hypoxia, resulting from the lack of convection-driven gas movement, has emerged as a possible major impact of microgravity. We developed transgenic Arabidopsis containing the alcohol dehydrogenase (Adh) gene promoter linked to the beta -glucuronidase (GUS) reporter gene to address specifically the possibility that spaceflight indu ces the plant hypoxia response and to assess whether any spaceflight respon se was similar to control terrestrial hypoxia-induced gene expression patte rns. The staining patterns resulting from a 5-d mission on the orbiter Colu mbia during mission STS-93 indicate that the Adh/GUS reporter gene was acti vated in roots during the flight, However, the patterns of expression were not identical to terrestrial control inductions. Moreover, although terrest rial hypoxia induces Adh/GUS expression in the shoot apex, no apex staining was observed in the spaceflight plants. This indicates that either the nor mal hypoxia response signaling is impaired in spaceflight or that spaceflig ht inappropriately induces Adh/GUS activity for reasons other than hypoxia.