Group Title: Utilization of autolytically active cell wall for characterization of tomato fruit softening /
Title: Utilization of autolytically active cell wall for characterization of tomato fruit softening
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Title: Utilization of autolytically active cell wall for characterization of tomato fruit softening
Physical Description: ix, 104 leaves : ill. ; 28 cm.
Language: English
Creator: Rushing, James Wayne, 1953- ( Dissertant )
Huber, Donald J. ( Thesis advisor )
Hall, Chesley B. ( Reviewer )
Humphreys, Thomas E. ( Reviewer )
Brown, Ross D. ( Reviewer )
Fry, Jack L. ( Degree grantor )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1985
Copyright Date: 1985
Subjects / Keywords: Horticultural Science thesis Ph. D
Tomatoes -- Ripening   ( lcsh )
Dissertations, Academic -- Horticulture -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Abstract: Cell walls from pericarp of normal tomato ( Lycopersicon esculentum Mil 1 . cv 'Rutgers') fruit released acid sugars in vitro in a reaction mediated by wall-bound polygalacturonase (PG; EC Release was negligible in walls from normal green and the ripening mutant rin fruit, reflecting the absence of PG in these tissues. Pectin solubilization was most extensive at pH 2.5 with a less pronounced optimum at 5.5. Brief exposure of cell wall to low (1.5) or high (7.5) pH resulted in reduction of autolytic activity, which also was inhibited by high temperature, calcium, and treatments employed to dissociate wall-bound protein. The rate and extent of acid sugar solubilization were dependent upon the techniques employed for handling the cell walls in vitro . Enzymically active cell walls subjected to either intermittent or continuous removal of the bathing medium released twice as muchpolyuronide as walls incubated in a static system. Protocol that maximized acid sugar solubilization was employed to determine the neutral sugar content and size distribution of pectic polymers released during autolysis. Approximately 2% of the initial wall dry weight was released as neutral sugars. The predominant products were galactose (50%) and arabinose (30%). Minor quantities of rhamnose, xylose, glucose, and mannose were also detected. The acid:neutral sugar ratio of soluble autolysis products decreased from 10.3 to 2.9 as wall degradation proceeded. Pectin molecular size did not change appreciably during autolytic reactions. Polyuronide solubilization was optimally enhanced by NaCl in the range of 200-300 mM. Pretreatment of enzymically active walls with 1 M NaCl in the pH range of 2.5-8.5 did not inhibit subsequent autolysis. The tenacity of PG-binding was further illustrated by the fact that 1 M NaCl treatments during wall extraction did not eliminate release of acid sugars. Interactions between pH, NaCl, and calcium were also investigated. The stimulation of wall-bound PG activity by 150-300 mM NaCl was most apparent at pH 2.5. Calcium (5 mM) did not inhibit autolysis at pH 2.5; however, at pH 4.5 calcium inhibition was apparent regardless of presence of NaCl. Polyuronide solubilization was negligible at pH 6.5 or 8.5.
Thesis: Thesis (Ph. D.)--University of Florida, 1985.
Bibliography: Bibliography: leaves 93-103.
Statement of Responsibility: by James Wayne Rushing.
Original Version: Typescript.
General Note: Vita.
 Record Information
Bibliographic ID: UF00099341
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000555150
oclc - 13573791
notis - ACY0028


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