RESUMO
In the Brassica genus, self-incompatibility (SI) is considered to be controlled by the combined action of several highly polymorphic genes located at the S-locus. These genes, including the S-Locus Gene (SLG), and the S-Receptor Kinase (SRK) are all members of the complex multigenic S-family. The S-Locus Related I gene (SLR1) is a member of the S-family, but is not involved in SI control since it is not linked to the S-locus and is essentially monomorphic. Here we confirm or demonstrate the occurrence of SLR1 as highly diverged but not very polymorphic genes in several genera of the Brassicaceae family (Arahidopsis, Brassica, Hirschfeldia, Raphanus, Sinapis). They show similar expression patterns with respect to location (stigmatic papillae), developmental stage (before and during anthesis) and transcript size (1.6 kb). In addition, they are assumed to be involved in the same biological function (late pollen adhesion). These features suggest that the pollen adhesion function might have evolved towards self-pollen recognition through duplication of SLR1 and recruitment of a protein kinase gene.
Assuntos
Brassica/genética , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Glicoproteínas/genética , Filogenia , Proteínas de Plantas/genética , Arabidopsis/genética , Sequência de Bases , Brassica/classificação , Regulação da Expressão Gênica no Desenvolvimento , Dados de Sequência Molecular , Mostardeira/genética , Plantas Medicinais , Polimorfismo de Fragmento de Restrição , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Especificidade da EspécieRESUMO
Self-incompatibility (SI) is a widespread mechanism in angiosperms which prevents self-fertilization. This mechanism relies on cell-cell interactions between pollen and pistil. Among the different SI systems that have been reported, two have been particularly investigated: the gametophytic system of Solanaceae and the sporophytic system of Brassicaceae. In these two families, although the molecular bases of SI response are different, secreted and/or membrane-anchored proteins are required for self-pollen rejection. Interestingly, these proteins exhibit two functions: recognition and a catalytic activity. In this review article, we present recent advances which permit a better understanding of how these proteins control the male/female recognition event associated with the SI response.
