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HELICAL SECONDARY CELL WALL  ORIENTATION  OF DEVELOPING PLANTS FROM THE NORTHERN HEMISPHERE  AFTER CLINOSTAT TREATMENT.  J.G. Taylor and N.D.  Livers.  Department of Biological Sciences, Ouachita Baptist University, Arkadelphia, Arkansas.

     An area of importance in future space travel research must include the growth and maintenance of plants in space.  Understanding the basic developmental characteristics of plants is essential in establishing a system that could be maintained in a weightless environment.  One very important anatomical feature of higher plants is the presence of secondary cell walls that give strength and rigidity to plant cells allowing a plant to attain a larger size.  Understanding secondary cell wall development can give insight into plant viability.  This research investigates the established helical secondary wall pattern of xylem cells in developing plants in the northern hemisphere and compares that pattern to differences that may be found in the same species grown in the southern hemisphere and in clinostat manipulated conditions.  Differences may be found between the northern and southern hemispheres due to the Coriolis Effect exerted by the rotation of the earth and possible disruption of normal gravitational influences on secondary wall development by use of a clinostat.  Microscopic analysis of control specimens of bean, radish, and Arabidopsis in collaboration with researchers in Argentina, South Africa, and China has demonstrated that the same specimens grown in those locations have no visible anatomical differences in helical secondary cell wall patterns when compared to the controls.  Each specimen was found to have a counter-clockwise spiraling orientation of the helical cell walls.  Specimens grown on a clinostat showed some minor variability in overall plant development, especially the roots, but the helical secondary cell wall orientation showed no obvious differences to the controls.  These results indicate that the Coriolis Effect and clinostat manipulations do not induce alterations in the helical cell wall patterns established in the embryos of the seed used in these experiments.

     (Supported by NASA: OBU10038 and OBU10039.)