Submitted to: Eukaryotic Cell
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/7/2007
Publication Date: 9/1/2007
Citation: Costanzo, S., Ospina-Giraldo, M., Deahl, K.L., Baker, C.J., Jones, R.W. 2007. Alternate Intron Processing of Family 5 Endoglucanase Transcripts from Genus Phytophthora. Eukaryotic Cell. 52:115-123. Interpretive Summary: Endoglucanases are enzymes that modify cellulose, a structural compound found in plant cell walls. Endoglucanases are important for industrial uses ranging from paper production to laundry detergents for cotton clothing. They can also play an important role in breaking down the plant cell wall, allowing microbes to attack plants. We have discovered a unique group of endoglucanases in the plant-infecting fungus Phytophthora. The genes for the endoglucanases are produced in different ways, suggesting that the fungus can make different types of endoglucanase from a single gene. This information will be useful for producing new endoglucanases, and for understanding how genes work in an important pathogen of plants.
Technical Abstract: In this study, twenty-one paralogs of family 5 endo-(1-4)-'-glucanase genes (EGs) were identified and characterized in the oomycete plant pathogens Phytophthora infestans, P. sojae and P. ramorum. Phylogenetic analysis revealed that these genes are in a unique group, with closest similarity being bacterial endoglucanases, an unusual feature for genes from the genus Phytophthora. Paralogs were clustered, and contained from none to three introns. Using reverse transcription RT-PCR to study expression levels, we detected partially matured RNA transcripts retaining one or more of their intronic regions. In some cases, the positions of exon splicing sites were also found to be variable. The relative proportions of these transcripts remain apparently unchanged under various growing conditions but differ among homologous copies of the three Phytophthora species. The alternate processing of introns in this group of EGs generates both coding and non-coding RNA isoforms. To our knowledge, this is the first report of alternative intron processing of oomycete transcripts.