Spaceflight exposure effects on transcription, activity, and localization of alcohol dehydrogenase in the roots of Arabidopsis thaliana

• Published in: Plant physiology (Bethesda) 1997-03, Vol.113 (3), p.685-693
• Main Authors: Porterfield, D.M. (Louisiana State University Agricultural Center, Baton Rouge, LA.), Matthews, S.W, Daugherty, C.J, Musgrave, M.E
• Format: Article
• Language: English
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; Alcohol Dehydrogenase - genetics; Alcohol Dehydrogenase - metabolism; ALCOHOL DESHIDROGENASA; Alcohols; ALCOOL DESHYDROGENASE; ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; ANOXIA; ANOXIE; Arabidopsis - enzymology; Arabidopsis - physiology; ARABIDOPSIS THALIANA; ARN MENSAJERO; ARN MESSAGER; BIOCHIMIE; Biological and medical sciences; BIOQUIMICA; Dehydrogenases; Enzymes; ESTRUCTURA CELULAR; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; GENES; GRAVIDEZ; GRAVITE; Hypoxia; Life Sciences (General); Metabolism; Microgravity; Oxygen; Plant growth; Plant physiology and development; Plant roots; Plant Roots - enzymology; Plants; RACINE; RAICES; Root tips; Space Flight; Space life sciences; STRUCTURE CELLULAIRE; TRANSCRIPCION; TRANSCRIPTION; Transcription, Genetic; ULTRAESTRUCTURA; ULTRASTRUCTURE; Whole Plant, Environmental, and Stress Physiology
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.3.685

Although considerable research and speculation have been directed toward understanding a plant's perception of gravity and the resulting gravitropic responses, little is known about the role of gravity-dependent physical processes in normal physiological function. These studies were conducted to determine whether the roots of plants exposed to spaceflight conditions may be experiencing hypoxia. Arabidopsis thaliana (L.) Heynh. plants were grown in agar medium during 6 or 11 d of spaceflight exposure on shuttle missions STS-54 (CHROMEX-03) and STS-68 (CHROMEX-05), respectively. The analysis included measurement of agar redox potential and root alcohol dehydrogenase (ADH) activity, localization, and expression. ADH activity increased by 89% as a result of spaceflight exposure for both CHROMEX-03 and -05 experiments, and ADH RNase protection assays revealed a 136% increase in ADH mRNA. The increase in ADH activity associated with the spaceflight roots was realized by a 28% decrease in oxygen availability in a ground-based study; however, no reduction in redox potential was observed in measurements of the spaceflight bulk agar. Spaceflight exposure appears to effect a hypoxic response in the roots of agar-grown plants that may be caused by changes in gravity-mediated fluid and/or gas behavior.