|Choi, Jane - FORMER USDA, ARS POST DOC|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2005
Publication Date: August 5, 2005
Citation: Luster, D.G., McMahon, M.B., Choi, J., Carter, M.L., Nunez, A., Frederick, R.D. 2005. Identification of proteins expressed in germinating Phakopsora pachyrhizi urediniospores [abstract]. Phytopathology. 95:S63. Technical Abstract: Phakopsora pachyrhizi is the causal agent of Asian soybean rust, a devastating disease that was recently identified in 9 U.S. states during the fall of 2004. In order to develop long-term strategies to combat this disease, we are focusing on proteins expressed in germinating spores and secreted by the fungus into the infection court prior to penetration. Our objectives in this study were to identify and characterize proteins expressed and secreted by P. Pachyrhizi urediniospores during germination. To accomplish this, we extracted and analyzed both total proteins and a cell wall protein fraction from P. pachyrhizi. Pachyrhizi urediniospores germinated on water for 18 hours. Trypsin-digested two-dimensional gel electrophoresis spots were peptide-fingerprinted and sequenced using Matrix-Assisted Laser Desorption/Ionization mass spectrometry with automated tandem time of flight fragmentation of selected ions. Proteins identified from the resulting peptide sequences by database searches within a confidence interval greater than or equal to 95 percent were evaluated and placed into functional categories. Proteins with putative roles in fungal infection and virulence were further identified from extracellular fractions washed from germinating urediniospores.