Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2008
Publication Date: 7/9/2008
Citation: Tucker, M.L., Puthoff, D.P., Neelam, A., Ehrenfried, M.L., Scheffler, B.E., Ballard, L.L., Campbell, K.B., Cooper, B. 2008. Analysis of expressed sequence tags from Uromyces appendiculatus hyphae and haustoria and their comparison to sequences from other rust fungi. Phytopathology. 98:1126-1135. Interpretive Summary: Rusts are important pathogens of many crop plants including soybean, bean and wheat. We have identified a set of genes in bean rust and wheat stem rust that share common characteristics of proteins that are secreted out of the fungus and into the host where they may directly affect gene expression in the host. Identification and characterization of these proteins is important to understanding the biology of pathogen/host interactions and the development of methods to combat these pathogens in agriculturally important crops. Both academic and commercial labs will use our findings.
Technical Abstract: Two separate cDNA libraries were prepared for RNA extracted from bean rust (Uromyces appendiculatus) hyphae and haustoria isolated from infected leaves bean leaves (Phaseolus vulgaris cv Pint 111) between 2 and 8 dpi. Approximately 13,000 clones were sequenced from both ends and the sequences assembled into contigs. Approximately 20% of the sequences were identified as having a plant origin and removed leaving 3,358 contigs and 929 singletons. Open reading frames (ORFs) of greater than 100 aa were identified and searched for putative signal sequences adequate for synthesis on the ER. Putative ORFs in the wheat stem rust (Puccinia graminis) genomic sequence have been identified by the Broad Institute (collaboration of the MIT and Harvard universities). These ORFs were subjected to a similarly analysis to identify putative signal sequences. Orthologous ORFs found in both the bean and wheat rusts were analyzed further to identify proteins that are potentially targeted to the host nucleus. Several candidate proteins were identified that may act as common rust virulence factors targeted to the plant nucleus.