title: Spaceflight reduces somatic embryogenesis in orchardgrass (Poaceae).
abstract: Somatic embryos initiate and develop from single mesophyll cells in in vitro cultured leaf segments of orchard-grass (Dactylis glomerata L.). Segments were plated at time periods ranging from 21 to 0.9 d (21 h) prior to launch on an 11 d spaceflight (STS-64). Using a paired t-test, there was no significant difference in embryogenesis from preplating periods of 14 d and 21 d. However, embryogenesis was reduced by 70% in segments plated 21 h before launch and this treatment was significant at P=0.0001. The initial cell divisions leading to embryo formation would be taking place during flight in this treatment. A higher ratio of anticlinal:periclinal first cell divisions observed in the flight compared to the control tissue suggests that microgravity affects axis determination and embryo polarity at a very early stage. A similar reduction in zygotic embryogenesis would reduce seed formation and have important implications for long-term space flight or colonization where seeds would be needed either for direct consumption or to grow another generation of plants.
authors.affiliation: Department of Plant and Soil Science, The University of Tennessee, Knoxville 37901-1071, USA. congerbv@utk.edu
authors.forename: B V
authors.initials: BV
authors.lastname: Conger
authors.forename: Z
authors.initials: Z
authors.lastname: Tomaszewski
authors.forename: J K
authors.initials: JK
authors.lastname: McDaniel
authors.forename: A
authors.initials: A
authors.lastname: Vasilenko
mesh_terms: D002869:Chromosome Aberrations; D046508:Culture Techniques; D008540:Meiosis; D048629:Micronuclei, Chromosome-Defective; D018515:Plant Leaves / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D006109:Poaceae / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D011058:Pollen / Q000196:embryology; D013026:Space Flight; D014893:Weightlessness