Dataset Information

Sequence and structural diversity of the S locus genes from different lines with the same self-recognition specificities in Brassica oleracea.

ABSTRACT: Self-incompatibility (SI) is a mechanism for preventing self-fertilization in flowering plants. In Brassica, it is controlled by a single multi-allelic locus, S, and it is believed that two highly polymorphic genes in the S locus, SLG and SRK, play central roles in self-recognition in stigmas. SRK is a putative receptor protein kinase, whose extracellular domain exhibits high similarity to SLG. We analyzed two pairs of lines showing cross-incompatibility (S(2) and S(2-b); S(13) and S(13-b)). In S(2) and S(2-b), SRKs were more highly conserved than SLGs. This was also the case with S(13) and S(13-b). This suggests that the SRKs of different lines must be conserved for the lines to have the same self-recognition specificity. In particular, SLG(2-b) showed only 88. 5% identity to SLG(2), which is comparable to that between the SLGs of different S haplotypes, while SRK(2-b) showed 97.3% identity to SRK(2) in the S domain. These findings suggest that the SLGs in these S haplotypes are not important for self-recognition in SI.

SUBMITTER: Kusaba M

PROVIDER: S-EPMC1460907 | biostudies-other | 2000 Jan

REPOSITORIES: biostudies-other

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Sequence and structural diversity of the S locus genes from different lines with the same self-recognition specificities in Brassica oleracea.

Kusaba M M Matsushita M M Okazaki K K Satta Y Y Nishio T T

Genetics 20000101 1

Self-incompatibility (SI) is a mechanism for preventing self-fertilization in flowering plants. In Brassica, it is controlled by a single multi-allelic locus, S, and it is believed that two highly polymorphic genes in the S locus, SLG and SRK, play central roles in self-recognition in stigmas. SRK is a putative receptor protein kinase, whose extracellular domain exhibits high similarity to SLG. We analyzed two pairs of lines showing cross-incompatibility (S(2) and S(2-b); S(13) and S(13-b)). In ...[more]

PMID: 10628999

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Project description:Non-self gametophytic self-incompatibility (GSI) recognition system is characterized by the presence of multiple F-box genes tandemly located in the S-locus, that regulate pollen specificity. This reproductive barrier is present in Solanaceae, Plantaginacea and Maleae (Rosaceae), but only in Petunia functional assays have been performed to get insight on how this recognition mechanism works. In this system, each of the encoded S-pollen proteins (called SLFs in Solanaceae and Plantaginaceae /SFBBs in Maleae) recognizes and interacts with a sub-set of non-self S-pistil proteins, called S-RNases, mediating their ubiquitination and degradation. In Petunia there are 17 SLF genes per S-haplotype, making impossible to determine experimentally each SLF specificity. Moreover, domain -swapping experiments are unlikely to be performed in large scale to determine S-pollen and S-pistil specificities. Phylogenetic analyses of the Petunia SLFs and those from two Solanum genomes, suggest that diversification of SLFs predate the two genera separation. Here we first identify putative SLF genes from nine Solanum and 10 Nicotiana genomes to determine how many gene lineages are present in the three genera, and the rate of origin of new SLF gene lineages. The use of multiple genomes per genera precludes the effect of incompleteness of the genome at the S-locus. The similar number of gene lineages in the three genera implies a comparable effective population size for these species, and number of specificities. The rate of origin of new specificities is one per 10 million years. Moreover, here we determine the amino acids positions under positive selection, those involved in SLF specificity recognition, using 10 Petunia S-haplotypes with more than 11 SLF genes. These 16 amino acid positions account for the differences of self-incompatible (SI) behavior described in the literature. When SLF and S-RNase proteins are divided according to the SI behavior, and the positively selected amino acids classified according to hydrophobicity, charge, polarity and size, we identified fixed differences between SI groups. According to the in silico 3D structure of the two proteins these amino acid positions interact. Therefore, this methodology can be used to infer SLF/S-RNase specificity recognition.

Dataset Information

Sequence and structural diversity of the S locus genes from different lines with the same self-recognition specificities in Brassica oleracea.

Publications

Sequence and structural diversity of the S locus genes from different lines with the same self-recognition specificities in Brassica oleracea.

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