ASGSB 1998 Annual Meeting Abstracts

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AUXIN-REGULATED GENE EXPRESSION OF TRANSGENIC TOMATO SEEDLINGS UNDER ALTERED GRAVITY ENVIRONMENTS. C.B. Vyas¹ and W.C. Piastuch². ¹Department of Animal Sciences, University of Vermont, Burlington and ²Plant Space Biology Laboratory, Dynamac Corporation, Kennedy Space Center, FL.

Plant growth and development has been shown to be affected in a microgravity environment. Studies have shown various morphological and physiological changes including inhibited growth, reduction in cell division, chromosomal damage, and disoriented growth. The growth hormone auxin is involved in plant growth and development and is shown to play a role in the gravitropic response. Recently it has been shown that corn plants grown in microgravity do not exhibit any overall changes in auxin levels. Therefore, if auxin levels are not affected in microgravity, perhaps the transport or tissue sensitivity to auxin may be affected in altered gravity environments. It is the objective of this study to measure auxin inducible gene expression and protein expression under altered gravity environments in a transgenic tomato line containing the GH3-GUS transgene system. Tomato seedlings were grown in altered gravity environment on a clinostat or centrifuge. Hypocotyls were harvested, then inverted and placed into an agar media containing auxin. The hypocotyls were place in various gravity environments for 24 hours. The hypocotyls were removed and placed in either X-GLUC substrate or frozen in liquid nitrogen for protein extraction. Protein was isolated through phenol:chloroform extraction and separated by two-dimensional SDS PAGE for comparative analysis.

Results have shown that the staining patterns of the hypocotyls were similar between various treatment groups. However, parenchyma staining was found to be more intense than vascular bundle staining. Auxin transport measured through X-GLUC staining found no significant differences between the various altered gravity environment. Significant variation in hypocotyl staining occurred in all treatments. Protein analysis between vertically grown plants and clinorotated plants found that protein expression may be diminished in clinorotated plants. (Supported by the NASA Space Life Sciences Training Program)

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