Synchronous expression of leghaemoglobin genes inMedicago truncatula during nitrogen-fixing root nodule development and response to exogenously supplied nitrate
| Autor: | Thierry Huguet, Etienne P. Journet, David G. Barker, Philippe Gallusci, Annie Dedieu |
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| Rok vydání: | 1991 |
| Předmět: |
Root nodule
Nitrogen Molecular Sequence Data Restriction Mapping Plant Development Plant Science chemistry.chemical_compound Ribonucleases Nitrogen Fixation Gene expression Genetics Amino Acid Sequence RNA Messenger Cloning Molecular Leghemoglobin Gene Regulation of gene expression Genomic Library Growth medium Nitrates Base Sequence biology General Medicine Plants Blotting Northern biology.organism_classification Medicago truncatula Gene Expression Regulation Biochemistry chemistry Nitrogen fixation Sequence Alignment Agronomy and Crop Science |
| Zdroj: | Plant Molecular Biology. 17:335-349 |
| ISSN: | 1573-5028 0167-4412 |
| DOI: | 10.1007/bf00040629 |
| Popis: | Two leghaemoglobin genes from the diploid, autogamous Medicago truncatula (Mtlb1 and Mtlb2) have been cloned and their nucleotide sequences determined. The deduced amino acid sequences encoded by these two genes differ significantly (18%), confirming that they belong to different sub-groups of Medicago leghaemoglobin genes. RNAse protection experiments have been used to show that both genes are transcriptionally active, and are expressed specifically in the nitrogen-fixing root nodule of M. truncatula. Whilst Mtlb1 mRNA is present at approximatively 3-fold higher steady-state levels than Mtlb2 mRNA, the transcription of both genes is triggered concomitantly during nodule development (5 days after inoculation with Rhizobium meliloti), and the ratio of the steady-state levels of the two mRNA species remains constant throughout nodule maturation. When the growth medium of nodulated M. truncatula is supplemented with 5 mM KNO3 over a period of 2-3 days there is a progressive drop in specific nitrogen fixation activity to only 20-25% of the original level. This is accompanied with a parallel and synchronous reduction in the quantities of mRNA corresponding to both Mtlb1 and Mtlb2. By contrast, the expression of the nodule parenchyma-specific gene ENOD2 is not significantly modified following nitrate treatment, clearly demonstrating differences in tissue-specific gene regulation in response to combined nitrogen. |
| Databáze: | OpenAIRE |
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