<abstract xmlns="http://www.w3.org/1999/xhtml"> The majority of verified plant disease resistance genes (R genes) isolated to date was of the nucleotide binding site-leucine rich repeat (NBS-LRR) class. The conservation between different NBS-LRR R genes opens the avenue for the use of PCR based strategies in isolating and cloning other R gene family members or analogs (resistance gene analogue, RGA) using degenerate primers for these conserved regions. In this study, to better understand the R gene in European aspen (Populus tremula), a perennial tree, we used degenerate primers to amplify RGA sequences from European aspen. Cloning and sequence characterization identified 37 European aspen RGAs, which could be phylogenetically classified into seven subfamilies. Deduced amino acid sequences of European aspen RGAs showed strong identity, ranging from 30.41 to 46.63%, to toll interleukin receptor (TIR) R gene subfamily. BLAST searches with reference to the genomic sequence of P. trichocarpa found 209 highly homologous regions distributed in 28 genomic loci, suggesting the abundance and divergence of NBS-encoding R genes in European aspen genome. Although, numerous studies have reported that plant R genes are under diversifying selection for specificity to evolving pathogens, non-synonymous to synonymous nucleotide substitution (dN/dS) ratio were &lt;1 for NBS domains of European aspen RGA, showing the evidence of purifying selection in this perennial tree. In further analysis, many intergenic exchanges were also detected among these RGAs, indicating a probable role in homogenising NBS domains. The present study permits insights into the origin, diversification, evolution and function of NBS-LRR R genes in perennial species like European aspen and will be useful for further R gene isolation and exploitation.</abstract>

The majority of verified plant disease resistance genes (R genes) isolated to date was of the nucleotide binding site-leucine rich repeat (NBS-LRR) class. The conservation between different NBS-LRR R genes opens the avenue for the use of PCR based strategies in isolating and cloning other R gene family members or analogs (resistance gene analogue, RGA) using degenerate primers for these conserved regions. In this study, to better understand the R gene in European aspen (Populus tremula), a perennial tree, we used degenerate primers to amplify RGA sequences from European aspen. Cloning and sequence characterization identified 37 European aspen RGAs, which could be phylogenetically classified into seven subfamilies. Deduced amino acid sequences of European aspen RGAs showed strong identity, ranging from 30.41 to 46.63%, to toll interleukin receptor (TIR) R gene subfamily. BLAST searches with reference to the genomic sequence of P. trichocarpa found 209 highly homologous regions distributed in 28 genomic loci, suggesting the abundance and divergence of NBS-encoding R genes in European aspen genome. Although, numerous studies have reported that plant R genes are under diversifying selection for specificity to evolving pathogens, non-synonymous to synonymous nucleotide substitution (dN/dS) ratio were <1 for NBS domains of European aspen RGA, showing the evidence of purifying selection in this perennial tree. In further analysis, many intergenic exchanges were also detected among these RGAs, indicating a probable role in homogenising NBS domains. The present study permits insights into the origin, diversification, evolution and function of NBS-LRR R genes in perennial species like European aspen and will be useful for further R gene isolation and exploitation.

Isolation, Characterization and Phylogenetic Analysis of Nucleotide Binding Site-encoding Disease-resistance Gene Analogues from European Aspen (Populus tremula)

Silvae Genetica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

The majority of verified plant disease resistance genes (R genes) isolated to date was of the nucleotide binding site-leucine rich repeat (NBS-LRR) class. The...

Isolation, Characterization and Phylogenetic Analysis of Nucleotide Binding Site-encoding Disease-resistance Gene Analogues from European Aspen (Populus tremula)

Published Online: Oct 20, 2017

Page range: 68 - 77

Received: Feb 05, 2010

DOI: https://doi.org/10.1515/sg-2010-0009

Keywords
Populus tremula, disease resistance gene, nucleotide binding site, resistance gene analogue, phylogenetic analysis

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Isolation, Characterization and Phylogenetic Analysis of Nucleotide Binding Site-encoding Disease-resistance Gene Analogues from European Aspen (Populus tremula)

Published Online: Oct 20, 2017

Page range: 68 - 77

Received: Feb 05, 2010

DOI: https://doi.org/10.1515/sg-2010-0009

KeywordsPopulus tremula, disease resistance gene, nucleotide binding site, resistance gene analogue, phylogenetic analysis

© 2017

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Keywords
Populus tremula, disease resistance gene, nucleotide binding site, resistance gene analogue, phylogenetic analysis