Medicago cell variants showing altered nitrogen utilization
G Giuliano1, G Mita, S E Indiogine
1Istituto di Mutagenesi e Differenziamento, CNR, Via Svezia 10, I-56100, Pisa, Italy.
Plant Cell Reports
|November 20, 2013
Summary
Mutagenesis of Medicago coerulea identified chlorate-resistant variants with altered nitrate reductase activity. Methylammonium-resistant variants displayed distinct nitrogen utilization regulation, showing less ammonium repression of nitrate reductase.
Area of Science:
- Plant molecular biology
- Nitrogen metabolism in plants
- Plant genetics
Background:
- Nitrate reductase is a key enzyme in plant nitrogen assimilation.
- Ammonium is known to repress nitrate reductase activity in wild-type plant cells.
- Understanding nitrogen utilization pathways is crucial for plant physiology and agriculture.
Purpose of the Study:
- To isolate and characterize chlorate-resistant and methylammonium-resistant variants of Medicago coerulea.
- To investigate the regulation of nitrogen utilization pathways in these variants.
- To identify genetic or regulatory changes affecting nitrate reductase and other nitrogen metabolism enzymes.
Main Methods:
- Mutagenesis of Medicago coerulea cells.
- Isolation of chlorate-resistant and methylammonium-resistant variants.
- Assay of nitrate reductase activity.
- Analysis of xanthine dehydrogenase activity and adenine uptake.
Main Results:
- Nineteen chlorate-resistant variants showed variable nitrate reductase activity (5-100% of wild type); xanthine dehydrogenase was unaffected.
- Methylammonium-resistant variants exhibited altered regulation of nitrogen utilization.
- These variants displayed reduced sensitivity to ammonium repression of nitrate reductase activity compared to wild-type cells.
Conclusions:
- Mutagenesis can generate variants with altered nitrogen assimilation pathways in Medicago coerulea.
- The identified variants provide insights into the complex regulation of nitrate reductase and nitrogen utilization.
- These findings contribute to understanding plant responses to nitrogen availability and potential applications in crop improvement.
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