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The promoter of a nodule-specific chitinase from Casuarina glauca, CgChi3, is down-regulated by wounding in a jasmonic acid-independent manner
Stockholm University, Faculty of Science, Department of Botany. (Katharina Pawlowski)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The promoter of the nodule-specific class III chitinase CgChi3 from the Australian actinorhizal tree Casuarina glauca (Fortunato et al., 2007) was amplified by genome walking. A CgChi3::GUS fusion was used to examine whether the organ- and cell type-specific expression pattern of CgChi3 could be transferred to other root nodule-forming plants, and whether the repression of promoter activity by wounding that had been found in C. glauca nodules, was conserved and whether it was due to jasmonic acid (JA) signalling.

Organ- and cell type-specific expression of the CgChi3 promoter was conserved in the distantly related actinorhizal species Datisca glomerata, but not in the legume Lotus japonicus where CgChi3 was active in roots, not in nodules. The repression of promoter activity in response to wounding was conserved in L. japonicus and independent of JA signalling.

URN: urn:nbn:se:su:diva-42404OAI: diva2:346013
Available from: 2010-08-30 Created: 2010-08-30 Last updated: 2010-08-30Bibliographically approved
In thesis
1. Conservation of transcription factors in infected cells of nitrogen-fixing root nodules
Open this publication in new window or tab >>Conservation of transcription factors in infected cells of nitrogen-fixing root nodules
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Infected cells of nitrogen-fixing root nodules are the only plant cells that can stably internally accommodate a eubacterial symbiont. In the context of studying the differentiation of infected cells, we set about to analyse the conservation of infected cell-specific transcription factors using altogether four different promoters from genes showing infected cell-specific expression, or nodule-specific expression. The activity of promoter-reporter gene constructs was compared in transgenic hairy root systems of three different root nodule-forming plant species. The model species were two actinorhizal plants; the tree Casuarina glauca and the riparian weed Datisca glomerata, and the model legume Lotus japonicus. C. glauca and D. glomerata belong to different phylogenetic subgroups (Fagales vs. Cucurbitales) of actinorhizal plants showing strong differences with regard to nodule morphology, -metabolism and infection mechanism.

The results indicate one type of infected cell-specific transcription factors previously shown to be conserved between legumes and C. glauca is also conserved in D. glomerata. However, another type of transcription factor specific to infection thread-containing cells of C. glauca and the model legume Medicago truncatula is not conserved in D. glomerata. These results indicate that in this group of actinorhizal plants, infection thread growth occurs via a different mechanism, a conclusion supported by cytological analysis.

Furthermore, the results indicate that gene expression in infected cells of root nodules can be achieved by control mechanisms other than cell type-specific transcription factors, and that in this context, phytohormone regulation deserves further study.

Place, publisher, year, edition, pages
Stockholm: Department of Botany, Stockholm University, 2010. 69 p.
root nodules, actinorhiza, legumes, infection thread, Frankia, subtilase, leghemoglobin, chitinase
National Category
Research subject
Plant Physiology
urn:nbn:se:su:diva-42389 (URN)978-91-7447-140-3 (ISBN)
Public defence
2010-10-08, Föresläsningssalen Botanicum, Lilla Frescativägen 5, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.Available from: 2010-09-16 Created: 2010-08-27 Last updated: 2010-08-30Bibliographically approved

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