Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2009
Publication Date: 12/8/2009
Publication URL: http://www.biomedcentral.com/content/pdf/1471-2164-10-586.pdf
Citation: Ma, J., Huang, X., Wang, X., Chen, X., Qu, Z., Huang, L., Kang, Z. 2009. Isolation of expressed genes during compatible interaction between stripe rust (Puccinia striiformis) and wheat using a cDNA library. BMC Genomics 10:586. Interpretive Summary: Wheat stripe rust is one of the most destructive diseases of wheat worldwide. To establish compatibility with the host, the pathogen forms special infection structures to invade the plant with minimal damage to host cells. Although compatible interaction between wheat and the pathogen has been studied using various approaches, research on molecular mechanisms of the interaction is limited. This study was aimed to develop an expression sequence tag (EST) database of wheat infected by the pathogen to determine transcription profiles of genes involved in compatible wheat-stripe rust interaction. A total of 5,793 ESTs with high quality were obtained, from which 2,746 unique genes were identified. Of the 2,746 genes, 52.8% showed the highest homologies with plant genes; 16.3% had higher homologies with fungi; and 30% of the genes were not found homolous genes in the GenBank database. About 50% of the ESTs showed significant matches to gene coding proteins with known functions; 20% of the ESTs were similar to genes coding for proteins with unknown functions; and 30% of the ESTs did not show similarity to any sequences in the database. Involvement of seven genes in the wheat-stripe rust interaction were determined. The results show that the cDNA library is useful in studying the plant-pathogen interactions.
Technical Abstract: Background: Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat worldwide. To establish compatibility with the host, Pst forms special infection structures to invade the plant with minimal damage to host cells. Although compatible interaction between wheat and Pst has been studied using various approaches, research on molecular mechanisms of the interaction is limited. The aim of this study was to develop an EST database of wheat infected by Pst in order to determine transcription profiles of genes involved in compatible wheat-Pst interaction. Results: Total RNA, extracted from susceptible infected wheat leaves harvested at 3, 5 and 8 days post inoculation (dpi), was used to create a cDNA library, from which 5,793 ESTs with high quality were obtained and clustered into 583 contigs and 2,160 singletons to give a set of 2,743 unisequences (GenBank accessions: GR302385 to GR305127). The BLASTx program was used to search for homologous genes of the unisequences in the GenBank non-redundant protein database. Of the 2,743 unisequences, 52.8% (the largest category) were highly homologous to plant genes; 16.3% to fungal genes and 30% of no-hit. The functional classification of all ESTs was established based on the database entry giving the best E-value using the Bevan's classification categories. About 50% of the ESTs were significantly homologous to genes encoding proteins with known functions; 20% were similar to genes encoding proteins with unknown functions and 30% did not have significant homology to any sequence in the database. The quantitative real-time PCR (qRT-PCR) analysis determined the transcription profiles and their involvement in the wheat-Pst interaction for seven of the gene. Conclusion: The cDNA library is useful for identifying the functional genes involved in the wheat-Pst compatible interaction, and established a new database for studying Pst pathogenesis genes and wheat defense genes. The transcription patterns of seven genes were confirmed by the qRT-PCR assay to be differentially expressed in wheat-Pst compatible and incompatible interaction.