TY - JOUR
AU - Tian, Dacheng
AB - While the presence/absence polymorphism is commonly observed in disease resistance (R-) genes in Arabidopsis, only a few R-genes under the presence/absence polymorphism (R-P/A) have been investigated. To understand the mechanism of the molecular evolution of R-P/A, we investigated genetic variation of nine R-P/A in A. thaliana from worldwide populations. The number of possessed R-genes varied widely among accessions (two to nine, on average 4.3 ± 1.6/accession). No pair of accessions shared the same haplotype, and no clear geographic differentiation was observed with respect to the pattern of presence/absence of the R-genes investigated. Presence allele frequencies also varied among loci (25–70%), and no linkage disequilibrium was detected among them. Although the LRR region in regular R-genes is known to be highly polymorphic and has a high Ka/Ks ratio in A. thaliana, nucleotide sequences of this region in the R-P/A showed a relatively low level of genetic variation (π = 0.0002–0.016) and low Ka/Ks (0.03–0.70, <1). In contrast, the nucleotide diversities around the deletion junction of R-P/A were constantly high between presence and absence accessions for the R-genes (Dxy = 0.031–0.103). Our results suggest that R-P/A loci evolved differently from other R-gene loci and that balancing selection plays an important role in molecular evolution of R-P/A.
TI - Unique Evolutionary Mechanism in R-Genes Under the Presence/Absence Polymorphism in Arabidopsis thaliana
JF - Genetics
DO - 10.1534/genetics.105.047290
DA - 2006-02-01
UR - https://www.deepdyve.com/lp/oxford-university-press/unique-evolutionary-mechanism-in-r-genes-under-the-presence-absence-DoGwOHdDiD
SP - 1243
EP - 1250
VL - 172
IS - 2
DP - DeepDyve
ER -