Evidence for rare recombination at the gametophytic self-incompatibility locus

Vieira, Cristina; Charlesworth, Deborah; Vieira, Jorge

doi:10.1038/sj.hdy.6800326

Cited by 35 publications

(29 citation statements)

References 41 publications

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“…Furthermore, recombination is suppressed in the genes in the A. lyrata S-locus complex . Other theoretical analyses of the RNase-based self-incompatibility system also support a low recombination rate within S-RNase in Solanaceae, Rosaceae, and Scrophulariaceae (Vieira et al 2003) and between S-RNase and a marker gene, 48A, in Nicotiana alata (Takebayashi et al 2004). Therefore, Brassica species are worthy of attention with respect to recombination in the S-locus complex.…”

Section: Discussionmentioning

confidence: 99%

Effects of Recombination on Hitchhiking Diversity in the Brassica Self-incompatibility Locus Complex

Takuno¹,

Fujimoto²,

Sugimura

et al. 2007

Genetics

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In self-incompatibility, a number of S haplotypes are maintained by frequency-dependent selection, which results in trans-specific S haplotypes. The region of several kilobases ($40-60 kb) from SP6 to SP2, including self-incompatibility-related genes and some adjacent genes in Brassica rapa, has high nucleotide diversity due to the hitchhiking effect, and therefore we call this region the ''S-locus complex.'' Recombination in the S-locus complex is considered to be suppressed. We sequenced regions of .50 kb of the S-locus complex of three S haplotypes in B. rapa and found higher nucleotide diversity in intergenic regions than in coding regions. Two highly similar regions of .10 kb were found between BrS-8 and BrS-46. Phylogenetic analysis using trans-specific S haplotypes (called interspecific pairs) of B. rapa and B. oleracea suggested that recombination reduced the nucleotide diversity in these two regions and that the genes not involved in self-incompatibility in the S-locus complex and the kinase domain, but not the S domain, of SRK have also experienced recombination. Recombination may reduce hitchhiking diversity in the S-locus complex, whereas the region from the S domain to SP11 would disfavor recombination.

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Section: Discussionmentioning

confidence: 99%

Effects of Recombination on Hitchhiking Diversity in the Brassica Self-incompatibility Locus Complex

Takuno¹,

Fujimoto²,

Sugimura

et al. 2007

Genetics

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“…Alternatively, recombination activity within the gene could mix existing variation in a combinatorial fashion to contribute to the rise of novel alleles. Such a mechanism has been suggested to explain the evolution of shared clusters among major histocompatibility complex (MHC) alleles (Hughes et al 1993;Yuhki and O'Brien 1994;Zangenberg et al 1995) and alleles of the gametophytic self-incompatibility (S) locus (Awadalla and Charlesworth 1999;Vieira et al 2003). Recombination within the gene may also have an advantage if it increases the effectiveness with which deleterious mutations are eliminated (Kondrashov 1984;Rice 2002).…”

Section: R Ecombination Generates Novel Genomic Var-mentioning

confidence: 99%

Pronounced Differences of Recombination Activity at the Sex Determination Locus of the Honeybee, a Locus Under Strong Balancing Selection

Hasselmann

Beye

2006

Genetics

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Recombination decreases the association of linked nucleotide sites and can influence levels of polymorphism in natural populations. When coupled with selection, recombination may relax potential conflict among linked genes, a concept that has played a central role in research on the evolution of recombination. The sex determination locus (SDL) of the honeybee is an informative example for exploring the combined forces of recombination, selection, and linkage on sequence evolution. Balancing selection at SDL is very strong and homozygous individuals at SDL are eliminated by worker bees. The recombination rate is increased up to four times that of the genomewide average in the region surrounding SDL. Analysis of nucleotide diversity (p) reveals a sevenfold increase of polymorphism within the sex determination gene complementary sex determiner (csd) that rapidly declines within 45 kb to levels of genomewide estimates. Although no recombination was observed within SDL, which contains csd, analyses of heterogeneity, shared polymorphic sites, and linkage disequilibrium (LD) show that recombination has contributed to the evolution of the 59 part of some csd sequences. Gene conversion, however, has not obviously contributed to the evolution of csd sequences. The local control of recombination appears to be related to SDL function and mode of selection. The homogenizing force of recombination is reduced within SDL, which preserves allelic differences and specificity, while the increase of recombination activity around SDL relaxes conflict between SDL and linked genes.

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“…As in the coding region of the SFB gene there are no introns, the different alleles of an individual, amplified using this general set of primers, cannot be distinguished on the basis of length differences on an agarose gel. This is in contrast with what is usually done when studying the S-RNase gene, where significant intron size variation is often observed between alleles (Vieira et al, 2003). Thus, the amplification product was cloned using the TA cloning kit (Invitrogen, Carlsbad, CA, USA).…”

Section: Sfb Pcr Amplificationsmentioning

confidence: 88%

“…A similar result is obtained when a set of 88 Prunus S-RNases compiled by Vieira et al (2007) is used (Po0.05). For Prunus S-RNases, other features compatible with recombination have been presented, although the evidence is still not unequivocal (Vieira et al, 2003;Nunes et al, 2006;Ortega et al, 2006). It is tempting to take such an excess of homoplasies as evidence for recombination.…”

Section: P Spinosa Sfb Sequencesmentioning

confidence: 99%

Inferences on the number and frequency of S-pollen gene (SFB) specificities in the polyploid Prunus spinosa

et al. 2008

Self Cite

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In flowering plants, self-incompatibility is a genetic mechanism that prevents self-fertilization. In gametophytic selfincompatibility (GSI), pollen specificity is encoded by the haploid genotype of the pollen tube. In GSI, specificities are maintained by frequency-dependent selection, and for diploid species, at equilibrium, equal specificity frequencies (isoplethy) are expected. This prediction has been tested in diploid, but never in polyploid self-incompatible species. For the latter, there is no theoretical expectation regarding isoplethy. Here, we report the first empirical study on specificity frequencies in a natural population of a polyploid self-incompatible species, Prunus spinosa. A total of 32 SFB (the pollen S gene) putative specificities are observed in a large sample from a natural population. Although P. spinosa is polyploid, the number of specificities found is similar to that reported for other diploid Rosaceae species. Unequal specificity frequencies are observed.

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Evidence for rare recombination at the gametophytic self-incompatibility locus

Cited by 35 publications

References 41 publications

Effects of Recombination on Hitchhiking Diversity in the Brassica Self-incompatibility Locus Complex

Effects of Recombination on Hitchhiking Diversity in the Brassica Self-incompatibility Locus Complex

Pronounced Differences of Recombination Activity at the Sex Determination Locus of the Honeybee, a Locus Under Strong Balancing Selection

Inferences on the number and frequency of S-pollen gene (SFB) specificities in the polyploid Prunus spinosa

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