These authors contributed equally to this work.
Comparative analysis of peanut NBS-LRR gene clusters suggests evolutionary innovation among duplicated domains and erosion of gene microsynteny
Article first published online: 27 JUN 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 192, Issue 1, pages 164–178, October 2011
How to Cite
Ratnaparkhe, M. B., Wang, X., Li, J., Compton, R. O., Rainville, L. K., Lemke, C., Kim, C., Tang, H. and Paterson, A. H. (2011), Comparative analysis of peanut NBS-LRR gene clusters suggests evolutionary innovation among duplicated domains and erosion of gene microsynteny. New Phytologist, 192: 164–178. doi: 10.1111/j.1469-8137.2011.03800.x
- Issue published online: 2 SEP 2011
- Article first published online: 27 JUN 2011
- Received: 24 March 2011, Accepted: 16 May 2011
- disease resistance;
- gene conversion;
- gene synteny;
- peanut (Arachis hypogaea);
- •Plant genomes contain numerous disease resistance genes (R genes) that play roles in defense against pathogens. Scarcity of genetic polymorphism makes peanut (Arachis hypogaea) especially vulnerable to a wide variety of pathogens.
- •Here, we isolated and characterized peanut bacterial artificial chromosomes (BACs) containing a high density of R genes. Analysis of two genomic regions identified several TIR-NBS-LRR (Toll-interleukin-1 receptor, nucleotide-binding site, leucine-rich repeat) resistance gene analogs or gene fragments. We reconstructed their evolutionary history characterized by tandem duplications, possibly facilitated by transposon activities. We found evidence of both intergenic and intragenic gene conversions and unequal crossing-over, which may be driving forces underlying the functional evolution of resistance.
- •Analysis of the sequence mutations, protein secondary structure and three-dimensional structures, all suggest that LRR domains are the primary contributor to the evolution of resistance genes. The central part of LRR regions, assumed to serve as the active core, may play a key role in the resistance function by having higher rates of duplication and DNA conversion than neighboring regions. The assumed active core is characterized by significantly enriched leucine residue composition, accumulation of positively selected sites, and shorter beta sheets.
- •Homologous resistance gene analog (RGA)-containing regions in peanut, soybean, Medicago, Arabidopsis and grape have only limited gene synteny and microcollinearity.