Date of Award
Master of Science
Theses & dissertations (Interdisciplinary)
Genetics; Bioinformatics and Computational Biology
Fusarium Solani f. sp. glycines (Fsg) have been reported to produce at least two phytotoxins. Cell-free Fsg-culture filtrates containing phytotoxins have been shown to induce the development of foliar sudden death syndrome (SDS) symptoms in soybean. We have investigated the changes in protein profiles of symptomatic leaves created by treatment with cell-free Fsg-culture filtrates prepared from Fsg isolates. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis was conducted to test the protein profiles of symptomatic and healthy leaves. An approximately 55 kDa protein was found to be degraded in leaves with SDS foliar symptom. MALDI-TOF MS was applied to determine the mass fingerprint of this protein. A protein sequence database (NCBInr 2003) search using the mass fingerprint revealed that the 55 kDa protein is the ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco, E.C. Number: 18.104.22.168) large subunit, which is involved in carbon assimilation adn photorespiration. The Rubisco large subunit degradation was confirmed by western hybridation. Light was important for degradation of Rubisco large subunit by cell-free Fsg-culture filtrates. Degradation of Rubisco large subunit is accompanied by accumulation of reactive oxygen species following exposure of cell-free Fsg-culture filtrate-fed seedlings to light. Terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay data suggested that programmed cell death is iniated in leaves of seedlings fed with cell-free Fsg culture-filtrates. The degradation of Rubisco large subunit, accumulation of free radicals and programmed cell death also occured in leaves fed with active column fractions prepared from cell-free Fsg-culture filtrates. It is suggested that cell-free Fsg culture-filtrted cause SDS foliar symptoms in a light dependent manner and foliar symptom development is accompanied by degradation of Rubisco large subunit and accumulation of reactive oxygen species.
Ji, Junli, "Investigation of soybean sudden death syndrome caused by Fusarium solani f. sp. glycines cell-free-culture-filtrates" (2004). Retrospective Theses and Dissertations. 20634.