Program Book - 27th Fungal Genetics Conference

FULL POSTER SESSION ABSTRACTSLaboratory, NC State University, Raleigh, NC.Magnaporthe oryzae, the causative agent of rice blast disease, infects plant leaves via formation of an appressorium which facilitates penetration of theleaf surface. In an effort to better understand the physiological changes accompanying the earliest stages of infection-related development, a nano-LCMS/MS-based global proteomics examination of conidial germination and cAMP-induced appressoria formation was undertaken at four distinctdevelopmental time points resulting in the identification of 3200 proteins. Label free quantification by spectral counting identified 591 proteins whoserelative abundance changed during germination. Furthermore, treatment of germinating conidia with cAMP to induce appressorium formation resulted inthe identification of 493 proteins whose relative abundance changed compared to untreated samples. In developing appressoria, changes in cell wallmodifying, transport, extracellular and plasma membrane localized proteins were observed. Proteomic analysis of a M. oryzae cAMP-dependent proteinkinase A (cpkA) mutant defective in appressorium formation following treatment with cAMP identified a subset of proteins whose regulation is dependenton cAMP signaling. A comparison of proteome and transcriptome data revealed little correlation between protein and transcript regulation. Finally, tobetter define the role of protein phosphorylation and the CPKA protein kinase during the development of appressoria, the phosphoproteome of M. oryzaeis being investigated. To date, a total of 980 phosphoproteins have been identified from conidia and experiments designed to identify changes in proteinphosphorylation during appressorium formation are in progress.574. Characterization of the binding site and downstream targets of the MST12 transcription factor in Magnaporthe oryzae. Guotian Li, Guanghui Wang,Jin-Rong Xu. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN.Rice blast caused by Magnaporthe oryzae is one of the most devastating diseases on rice. In M. oryzae, appressorium formation is regulated by PMK1mitogen-activated protein kinase (MAPK) pathway. Its orthologs are conserved a wide array of plant pathogenic fungi for regulating different plantinfection processes. In M. oryzae, one of the transcription factors functioning downstream from Pmk1 is Mst12 that is essential for appressoriumpenetration and invasive growth. The MST12-GFP transformant showed strongest GFP signals in appressoria and invasive hyphae. Pmk1 weakly interactedwith Mst12 in yeast two-hybrid assays. Overexpression of MST12 failed to complement the defects of the pmk1 mutant, suggesting that the activation ofMst12 by Pmk1 was required for its function. Site-directly mutagenesis analysis indicated that the MAPK-docking region and phosphorylation site wereessential for the function of MST12. However, mutant alleles of MST12 with point mutations in any one of the two tandem zinc finger domains were stillpartially functional, indicating their overlapping or redundant functions. Expression of MST12 functionally rescued the invasive growth defects of the yeastste12 mutant and EMSA analyses suggested that Mst12 had a binding site similar to the PRE sequence recognized by Ste12. During appressoriumformation, transcription levels of 222 genes were found to be significantly altered in the mst12 mutant (P