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United States Department of Agriculture

Agricultural Research Service

Title: Contribution of Cytochrome C and Alternative Axidase Pathways to Respiratory Sucrose Loss in Postharvest Sugarbeet (Beta Vulgaris L.) Roots.

Authors
item Fugate, Karen
item Anderson, Marc - NORTH DAKOTA STATE UNIV
item Finger, Fernando - UNIV FEDERAL DE VICOSA

Submitted to: American Society of Sugarbeet Technologists
Publication Type: Proceedings
Publication Acceptance Date: February 21, 2003
Publication Date: July 15, 2003
Citation: KLOTZ, K.L., ANDERSON, M., FINGER, F. CONTRIBUTION OF CYTOCHROME C AND ALTERNATIVE AXIDASE PATHWAYS TO RESPIRATORY SUCROSE LOSS IN POSTHARVEST SUGARBEET (BETA VULGARIS L.) ROOTS. Proceedings of the 1st Joint International Institute for Beet Research and the American Society of Sugar Beet Technologists Congress. 2003. p. 915-919.

Interpretive Summary: It is estimated that respiration is responsible for approximately 70% of the sucrose loss that occurs during sugarbeet root storage. Respiration is the process that breaks down carbohydrates to carbon dioxide to generate metabolic energy and substrates needed to maintain healthy tissue during storage, heal wounds acquired during harvest and defend against pathogens. Two respiratory pathways, the cytochrome c oxidase pathway and the alternative oxidase pathway, contribute to total respiration in all plants. In sugarbeet, little information is available on the role of these two pathways in sucrose utilization and postharvest losses. This information, however, would improve our understanding of this physiological process and may provide insight into methods to reduce postharvest respiratory sucrose loss. Analyses of the changes in total respiration and the contribution of the two pathways in sugarbeet roots subjected to different storage conditions and durations, and in response to typical harvest stresses are in progress. Initial results indicate that the cytochrome c respiratory pathway predominates in healthy roots, and that the relative activities of the two pathways change little in response to wounding, time in storage, or storage temperature. Respiration was approximately 8-fold higher at the root surface than in the internal tissue of the root, and internal tissue of the crown respired at a rate that was approximately 1.5-fold greater than the internal tissue of the root.

Technical Abstract: It is estimated that respiration is responsible for approximately 70% of the sucrose loss that occurs during postharvest storage of sugarbeet roots. Respiration provides the metabolic energy and carbon substrates needed to maintain healthy tissue during storage, heal wounds acquired during harvest and defend against pathogens. Two respiratory pathways, the cytochrome c oxidase pathway and the alternative oxidase pathway, contribute to total respiration. In sugarbeet, little information is available on the role of these two pathways in sucrose utilization and postharvest losses. This information, however, would improve our understanding of this physiological process and may provide insight into methods to reduce postharvest respiratory sucrose loss. Analyses of the changes in total respiration and the contribution of the two pathways in sugarbeet roots subjected to different storage conditions and durations, and in response to typical harvest stresses are in progress. Initial results indicate that the cytochrome c respiratory pathway predominates in healthy unwounded and wounded sugarbeet roots, and that the relative capacities of the two pathways change little in response to wounding, time in storage, or storage temperature. Respiration was approximately 8-fold higher at the root surface and 1.5-fold higher in the internal tissue of the crown than in the root internal tissue.

Last Modified: 11/1/2014
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