Isolation of a family of resistance gene analogue sequences of the nucleotide binding site (NBS) type fromLensspecies

Genome ◽  
2004 ◽  
Vol 47 (4) ◽  
pp. 650-659 ◽  
Author(s):  
M W.F Yaish ◽  
L E Sáenz de Miera ◽  
M Pérez de la Vega

Most known plant disease-resistance genes (R genes) include in their encoded products domains such as a nucleotide-binding site (NBS) or leucine-rich repeats (LRRs). Sequences with unknown function, but encoding these conserved domains, have been defined as resistance gene analogues (RGAs). The conserved motifs within plant NBS domains make it possible to use degenerate primers and PCR to isolate RGAs. We used degenerate primers deduced from conserved motifs in the NBS domain of NBS-LRR resistance proteins to amplify genomic sequences from Lens species. Fragments from approximately 500-850 bp were obtained. The nucleotide sequence analysis of these fragments revealed 32 different RGA sequences in Lens species with a high similarity (up to 91%) to RGAs from other plants. The predicted amino acid sequences showed that lentil sequences contain all the conserved motifs (P-loop, kinase-2, kinase-3a, GLPL, and MHD) present in the majority of other known plant NBS–LRR resistance genes. Phylogenetic analyses grouped the Lens NBS sequences with the Toll and interleukin-1 receptor (TIR) subclass of NBS–LRR genes, as well as with RGA sequences isolated from other legume species. Using inverse PCR on one putative RGA of lentil, we were able to amplify the flanking regions of this sequence, which contained features found in R proteins.Key words: disease resistance genes, comparative analysis, lentils, TIR, LRR.

FEBS Journal ◽  
2012 ◽  
Vol 279 (13) ◽  
pp. 2431-2443 ◽  
Author(s):  
Ying Cheng ◽  
Xiaoyu Li ◽  
Haiyang Jiang ◽  
Wei Ma ◽  
Weiyun Miao ◽  
...  

Genome ◽  
1998 ◽  
Vol 41 (6) ◽  
pp. 782-788 ◽  
Author(s):  
W Spielmeyer ◽  
M Robertson ◽  
N Collins ◽  
D Leister ◽  
P Schulze-Lefert ◽  
...  

In this study, resistance gene analogs (RGAs) which were isolated from monocot crop species (wheat, barley, maize and rice) and contained conserved sequence motifs found within the nucleotide binding site - leucine rich repeat (NBS-LRR) class of resistance genes, were used to assess their distribution in the wheat genome. The RGAs showed 30-70% amino acid identity to a previously isolated monocot NBS-LRR sequence from the Cre3 locus for cereal cyst nematode (CCN) resistance in wheat. We used the RGAs as probes to identify and map loci in wheat using recombinant inbred lines of an international Triticeae mapping family. RGA loci mapped across all seven homoeologous chromosome groups of wheat. This study demonstrated that the RGA mapping approach provides potential entry points toward identifying resistance gene candidates in wheat.Key words: wheat, disease resistance genes, nucleotide binding site, leucine rich repeat, resistance gene analogs.


2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Shenglong Tan ◽  
Song Wu

Nucleotide-binding site (NBS) disease resistance genes play an important role in defending plants from a variety of pathogens and insect pests. Many R-genes have been identified in various plant species. However, little is known about the NBS-encoding genes inBrachypodium distachyon. In this study, using computational analysis of theB. distachyongenome, we identified 126 regular NBS-encoding genes and characterized them on the bases of structural diversity, conserved protein motifs, chromosomal locations, gene duplications, promoter region, and phylogenetic relationships. EST hits and full-length cDNA sequences (fromBrachypodiumdatabase) of 126 R-like candidates supported their existence. Based on the occurrence of conserved protein motifs such as coiled-coil (CC), NBS, leucine-rich repeat (LRR), these regular NBS-LRR genes were classified into four subgroups: CC-NBS-LRR, NBS-LRR, CC-NBS, and X-NBS. Further expression analysis of the regular NBS-encoding genes inBrachypodiumdatabase revealed that these genes are expressed in a wide range of libraries, including those constructed from various developmental stages, tissue types, and drought challenged or nonchallenged tissue.


2010 ◽  
Vol 59 (1-6) ◽  
pp. 68-77 ◽  
Author(s):  
Yong Zhang ◽  
Shougong Zhang ◽  
Liwang Qi ◽  
Tao Zhang ◽  
Chunguo Wang ◽  
...  

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.


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