An anther-specific gene encoded by an S locus haplotype of Brassica produces complementary and differentially regulated transcripts.

Boyes, Douglas C.; Nasrallah, June B.

doi:10.1105/tpc.7.8.1283

Cited by 69 publications

(18 citation statements)

References 51 publications

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“…Such an analysis would be informative not only in relation to the evolution of S haplotypes but also, by analogy to the Chlamydomonas mating-type locus (Ferris and Goodenough, 1994), for placing outer limits on the extent of the S locus, thereby defining the full complement of genes that constitute a specificity-encoding S haplotype. Currently, however, no estimates exist for the actual frequency of recombination in the chromosomal region containing the S locus and in other regions of the Brassica genome, even though Brassica linkage maps are available (Slocum et al, 1990;Song et al, 1991) and the S locus has been positioned on at least one such linkage map (Camargo et al, 1997). Nevertheless, the frequency of recombination in the S locus region must be relatively low.…”

Section: Discussionmentioning

confidence: 99%

The self-incompatibility (S) haplotypes of Brassica contain highly divergent and rearranged sequences of ancient origin.

et al. 1997

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In Brassica, the recognition of self-related pollen by the stigma is controlled by the highly polymorphic S locus that encodes several linked and coadapted genes and can span several hundred kilobases. We used pulsed-field gel electrophoresis to analyze the structure of different S haplotypes. We show that the S, and S,3 haplotypes of Brassica oleracea contain extensive sequence divergence and rearrangement relative to each other. In contrast, haplotypic configuration is more conserved between 8. oleracea S,3 and 8. campestris s,, two haplotypes that have been proposed to be derived from a common ancestral haplotype based on sequence comparisons. These results support the view that extensive restructuring of the S locus preceded speciation in Brassica. This structural heteromorphism, together with haplotype-specific sequences, may suppress recombination within the S locus complex, potentially providing a mechanism for maintaining the linkage of coadapted allelic combinations of genes over time.

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Section: Discussionmentioning

confidence: 99%

The self-incompatibility (S) haplotypes of Brassica contain highly divergent and rearranged sequences of ancient origin.

et al. 1997

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“…Such studies also may elucidate the mechanisms that underlie S locus translocation in different lineages and those that underlie the restructuring of the S locus in a particular lineage. In this context, note that the Sa and Sb haplotypes of A. lyrata, the S locus region of A. thaliana, and several Brassica S haplotypes (Boyes and Nasrallah, 1995;Pastuglia et al, 1997b;Cui et al, 1999;Suzuki et al, 1999) all contain retroelement-like sequences. It is possible that retroelement activity, which is thought to be an effective agent of genome reorganization (Bennetzen, 1996), may have played a role in the translocation and restructuring of the S locus in the Brassicaceae.…”

Section: Discussionmentioning

confidence: 99%

Self-Incompatibility in the Genus Arabidopsis: Characterization of the S Locus in the Outcrossing A. lyrata and Its Autogamous Relative A. thaliana

Kusaba¹,

Dwyer²,

Hendershot³

et al. 2001

The Plant Cell

131

282

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As a starting point for a phylogenetic study of self-incompatibility (SI) in crucifers and to elucidate the genetic basis of transitions between outcrossing and self-fertilizing mating systems in this family, we investigated the SI system of Arabidopsis lyrata . A. lyrata is an outcrossing close relative of the self-fertile A. thaliana and is thought to have diverged from A. thaliana ‫ف‬ 5 million years ago and from Brassica spp 15 to 20 million years ago. Analysis of two S (sterility) locus haplotypes demonstrates that the A. lyrata S locus contains tightly linked orthologs of the S locus receptor kinase ( SRK ) gene and the S locus cysteine-rich protein ( SCR ) gene, which are the determinants of SI specificity in stigma and pollen, respectively, but lacks an S locus glycoprotein gene. As described previously in Brassica , the S haplotypes of A. lyrata differ by the rearranged order of their genes and by their variable physical sizes. Comparative mapping of the A. lyrata and Brassica S loci indicates that the S locus of crucifers is a dynamic locus that has undergone several duplication events since the Arabidopsis-Brassica split and was translocated as a unit between two distant chromosomal locations during diversification of the two taxa. Furthermore, comparative analysis of the S locus region of A. lyrata and its homeolog in self-fertile A. thaliana identified orthologs of the SRK and SCR genes and demonstrated that self-compatibility in this species is associated with inactivation of SI specificity genes. INTRODUCTIONSelf-incompatibility (SI) is the major outcrossing mechanism in the family Brassicaceae (de Nettancourt, 1977). Species in this family have been grouped into 19 tribes on the basis of morphological criteria (Schultz, 1936), and SI has been described in all tribes analyzed to date. When Bateman (1955) surveyed 182 species distributed in 11 tribes, he found that approximately half of these species included selfincompatible accessions. In a survey of 59 taxa in the subtribe Brassicineae of the tribe Brassiceae (which includes Brassica and Raphanus ), 50 taxa were self-incompatible (Takahata and Hinata, 1980). In all cases analyzed, SI has been shown to be controlled sporophytically by a single S (sterility) locus, with multiple alleles or variants and complex dominance relationships between alleles (Bateman, 1954(Bateman, , 1955Thompson and Taylor, 1966): in self-incompatible plants, pollen will not develop on a stigma that expresses the same S alleles as the pollen parent.Molecular analysis of the Brassica S locus region has shown that this mendelian locus is a gene complex consisting of distinct stigma-expressed and anther-expressed genes that determine SI specificity in stigma and pollen, respectively (reviewed in Nasrallah, 2000). The SRK (for S locus receptor kinase) gene (Stein et al., 1991) encodes a plasma membrane-spanning receptor serine/threonine kinase specific to the stigma epidermis (Stein et al., 1996) and is the determinant of SI specificity in the stigma (Takasaki et al., 2000). ...

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“…In particular, we anticipate the presence of a pollen-expressed determinant of recognition that would act as a haplotype-specific ligand of SRK and SLG. A recently described gene, the S locus anther (SLA) gene, possesses several features expected of a recognition determinant, including linkage to the S locus, haplotype-specific polymorphism, and anther-specific expression (Boyes and Nasrallah, 1995). It remains to be determined whether the polypeptides of 7.5 and 10 kD potentially encoded by SLA transcripts are expressed on the pollen surface and are capable of interacting with SRK and SLG.…”

Section: Lmplications For the Mechanism Of Si In Brassica And Receptomentioning

confidence: 99%

SRK, the stigma-specific S locus receptor kinase of Brassica, is targeted to the plasma membrane in transgenic tobacco.

et al. 1996

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The S locus receptor kinase (SRK) gene is one of two S locus genes required for the self-incompatibility response in Brassica. We have identified the product of the SRKs gene in 6. oleracea stigmas and have shown that it has characteristics of an integral membrane protein. When expressed in transgenic tobacco, SRK6 is glycosylated and targeted to the plasma membrane. These results provide definitive biochemical evidence for the existence in plants of a plasma membrane-localized transmembrane protein kinase with a known cell-cell recognition function. The timing of SRK expression in stigmas follows a time course similar to that previously described for another S locus-linked gene, the S locus glycoprotein (SLG) gene, and correlates with the ability of stigmas to mount a self-incompatibility response. Based on SRK6 promoter studies, the site of gene expression overlaps with that of SLG and exhibits predominant expression in the stigmatic papillar cells. Although reporter gene studies indicated that the SRK promoter was active in pollen, SRK protein was not detected in pollen, suggesting that SRK functions as a cell surface receptor exclusively in the papillar cells of the stigma.

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An anther-specific gene encoded by an S locus haplotype of Brassica produces complementary and differentially regulated transcripts.

Cited by 69 publications

References 51 publications

The self-incompatibility (S) haplotypes of Brassica contain highly divergent and rearranged sequences of ancient origin.

The self-incompatibility (S) haplotypes of Brassica contain highly divergent and rearranged sequences of ancient origin.

Self-Incompatibility in the Genus Arabidopsis: Characterization of the S Locus in the Outcrossing A. lyrata and Its Autogamous Relative A. thaliana

SRK, the stigma-specific S locus receptor kinase of Brassica, is targeted to the plasma membrane in transgenic tobacco.

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