ASGSB 1999 Annual Meeting Abstracts

ETHYLENE INDUCED ABNORMALITY IN "SUPER DWARF" WHEAT REPRODUCTIVE DEVELOPMENT IS IDENTICAL TO MIR-GROWN SAMPLES. D.L. Bubenheim and J.Stieber. NASA Ames Research Center, Ecosystem Science and Technology, Moffett Field CA.

Super-dwarf wheat grown on the Mir space station using the Svet Greenhouse exhibited morphological, metabolic and reproductive abnormalities compared with normal wheat.  Of prominent importance were the abnormalities associated with reproductive ontogeny and the total absence of seed formation on Mir.  Changes in the apical meristem associated with transition from the vegetative phase to floral initiation and development of the reproductive spike were all typical of "Super Dwarf" wheat up to the point of anthesis.  Observation of ruptured anthers from the Mir-grown plants revealed what appeared to be normally developed pollen. These pollen grains, however, contain only one nucleus, while normal viable pollen is trinucleate. A potentially important difference in the flight experiment, compared with ground reference studies, was identified - a high level of atmospheric ethylene (1200 ppb).  Ground studies conducted exposing "Super-dwarf" wheat to ethylene just prior to anthesis resulted in manifestation of the same abnormalities observed in the space flight samples.

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