Submitted to: Journal of Sugarbeet Research
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/1999
Publication Date: N/A
Technical Abstract: It has long been known that the major enzymes involved in sucrose catabolism in plants are the invertases and sucrose synthases. The role of these enzymes in sucrose losses in sugarbeets during growth and development and postharvest storage, however, is unclear. Past studies have provided conflicting results as to the relative importance of these two enzymes in sucrose loss in sugarbeet. These conflicts may arise from the nature of the enzymes involved. In most plants, invertase and sucrose synthase are not single enzymes, but families of enzymes, consisting of several isoforms. It is likely that the different isoenzymes of an enzyme family perform different functions and are important at different developmental stages. Enzyme activity assays, however, typically measure total activity for the family, no the individual isoenzymes. My objectives is to determine the relative role of the individual isoenzymes for sucrose catabolism by comparing their activity relative to sucrose content and respiration. Total sucrose synthase activity, soluble and insoluble acid invertase activity, and alkaline invertase activity will be measure d in relation to carbohydrate content and root respiration. Activity of the individual isoenzymes will then be determined using activity staining of isoelectric focusing or nondenaturing protein gels and RT-PCR. This approach will be used to examine the roles of sucrose synthase and invertase isoenzymes during growth and development and postharvest storage. This paper will present the research goals, research plan preliminary results of this work.