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ANTHER STRUCTURE AND POLLEN DEVELOPMENT IN BRASSICA PLANTS GROWN DURING SPACEFLIGHT A. Kuang¹ and M. E. Musgrave^{2 1}Department of Biology, The University of Texas – Pan American, Edinburgh, TX  78539; ²Biology Department, University of Massachusetts, MA  01003

     Anthers play an important role in providing nutrients and acting as  chambers for pollen development. There is little information available  regarding the correlation of anther development and pollen development in the microgravity environment.  The current study investigates the changes in the structure of anthers and corresponding pollen grains of Brassica rapa L., cv. CrGC#1-33 plants grown on board the MIR space station and on the ground.  Brassica rapa plants (13 d-old) developed on the MIR space station and on the ground were preserved in a buffered solution containing 1% formaldehyde and 0.5% glutaraldehyde. Post-flight, flowers were dissected from the preserved plants and post-fixed in 1% Osmium.  Anthers from those flowers were processed and prepared for light and electron microscope observation.  The results show that numerous large starch grains are present in the cells of the anther wall and filaments in space plants, while starch grains are rarely observed in those cells of the ground plants.  There is no difference on the organization of the anther wall between space and the ground control materials.  However, the inner layer of anther wall, tapetum, was swollen and the tapetal plasmodium intruded into the anther chambers.  The swollen tapetal layer persisted to a later developmental stage in the spaceflight material whereas it degenerated at an earlier developmental stage in the ground plants.  Most pollen grains appeared normal.  The results suggest that despite the storage of starch grains in the anther wall and the persistence of tapetum, the nutrients necessary for pollen development were supplied in microgravity.

     (Supported by NASA grant NAG2-1375.)