PLANT PHYSIOLOGY , Vol 109, Issue 2 637-643, Copyright © 1995 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Effect of High Temperature on Plant Growth and Carbohydrate Metabolism in Potato
A. M. Lafta and J. H. Lorenzen
Department of Plant Sciences, North Dakota State University, Fargo, North Dakota 58105
This study was undertaken to determine the role of sucrose-metabolizing
enzymes in altered carbohydrate partitioning caused by heat stress. Potato
(Solanum tuberosum L.) genotypes characterized as susceptible and tolerant
to heat stress were grown at 19/17[deg]C, and a subset was transferred to
31/29[deg]C. Data were obtained for plant growth and photosynthesis. Enzyme
activity was determined for sucrose-6-phosphate synthase (SPS) in mature
leaves and for sucrose synthase, ADP-glucose pyrophosphorylase, and
UDP-glucose pyrophosphorylase in developing tubers of plants. High
temperatures reduced growth of tubers more than of shoots. Photosynthetic
rates were unaffected or increased slightly at the higher temperature. Heat
stress increased accumulation of foliar sucrose and decreased starch
accumulation in mature leaves but did not affect glucose. SPS activity
increased significantly in mature leaves of plants subjected to high
temperature. Changes in SPS activity were probably not due to altered
enzyme kinetics. The activity of sucrose synthase and ADP-glucose
pyrophosphorylase was reduced in tubers, albeit less quickly than leaf SPS
activity. There was no interaction of temperature and genotype with regard
to the enzymes examined; therefore, observed differences do not account for
differences between genotypes in heat susceptibility.