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Molecular evolution of nitrate reductase genes
1Department of Genetics and Cell Biology, Washington State University, Pullman 99164-6420, USA.
Journal of Molecular Evolution
|April 1, 1996
Summary
Nitrate reductase (NR) gene analysis reveals conserved functional domains and evolutionary rates across fungi, algae, and plants. Phylogenetic analysis of NR genes accurately reflects organismal relationships and aids in estimating divergence times.
Area of Science:
- Molecular Evolution
- Bioinformatics
- Genomics
Background:
- Nitrate reductases (NRs) are crucial enzymes in nitrogen assimilation.
- Understanding NR gene evolution provides insights into plant and fungal phylogeny.
- Comparative analysis of NR genes across diverse taxa is essential for evolutionary studies.
Purpose of the Study:
- To investigate the evolutionary mechanisms and phylogenetic relationships of nitrate reductase (NR) genes.
- To analyze sequence similarities, substitution rates, and intron positions within NR genes.
- To estimate divergence times of major plant lineages using NR gene data.
Main Methods:
- Nucleotide sequence analysis of 19 NR genes from 16 species (fungi, algae, higher plants).
- Estimation of overall and nonsynonymous substitution rates.
- Phylogenetic tree construction and relative rate tests.
Main Results:
- High sequence similarity observed in functional domains of NR genes, with variations in GC content and intron number.
- Intron positions are conserved within fungi and plants separately.
- Estimated divergence times for monocots and dicots range from 191 to 340 Myr, consistent with other studies.
Conclusions:
- NR genes provide a reliable marker for reconstructing evolutionary histories.
- The evolutionary rates of NR functional domains are slower than flanking regions.
- Phylogenetic analysis of NR genes supports existing organismal classifications and aids in divergence time estimations.