Cloning and molecular characterization of new genes constitutes a useful approach in studying the symbiotic interactions between the model plant Medicago truncatula and Synorhizobium meliloti. Large numbers of expressed sequence tags (ESTs) available for Medicago truncatula, along with numerous cDNA, oligonucleotides, and Affimetrix DNA microarray chips, represent useful tools for gene discovery. In an attempt to identify a new gene that might be involved in the process of nodulation in Medicago truncatula, preliminary data reported by Fedorova et al. (2002), who identified 340 putative gene products or tentative consensus sequences (TCs) expressed only in nodules, was used. This research was focused on TC33166 (TC103185), which has 3 ESTs in the TC, and whose strongest BLASTX hit of TC103185 is the incomplete root hair elongation (IRE) protein kinase-like protein (NP_192429) from Arabidopsis thaliana. The Arabidopsis IRE gene is required for normal root hair growth, and a role in apical growth was suggested (Oyama et al., 2002). Infection thread growth can be looked at as an inward growth of the root hair. Thus, TC103185 was a good candidate for identifying a gene that may be involved in early events of nodulation. MtIRE (GenBank accession AC122727) is organized in 17 exons and 16 introns, similarly to the Arabidopsis IRE gene. MtIRE is a new member of the IRE family and it is a putative Ser/Thr protein kinase. MtIRE is a nodule- and flower-specific gene, suggesting that nodulation may have recruited it from other developmental processes. MtIRE is likely to be involved in the invasion process, or in the maturation of the symbiosome, or of the cells that contain rhizobia, rather than infection thread initiation and elongation or in nitrogen fixation. Nodule invasion precedes the onset of MtIRE expression and the expression pattern changes in time within the nodule. RNA interference results support MtIRE expression data and suggest a possible role in preventing extensive defense responses. Our study demonstrates the existence of an Arabidopsis IRE homolog in Medicago truncatula root nodules with an entirely new function and regulation.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc5215 |
| Date | 05 1900 |
| Creators | Pislariu, Catalina Iulia |
| Contributors | Dickstein, Rebecca, Benjamin, Robert C., Root, Douglas D., Ayre, Brian G., Knesek, John |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | Text |
| Rights | Use restricted to UNT Community, Copyright, Pislariu, Catalina Iulia, Copyright is held by the author, unless otherwise noted. All rights reserved. |
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