Abstract
Selfing is a frequent evolutionary trend in angiosperms, and is a suitable model for studying the recurrent patterns underlying adaptive evolution. Many plants avoid self-fertilization by physiological processes referred to as self-incompatibility (SI). In the Brassicaceae, direct and specific interactions between the male ligand SP11/SCR and the female receptor kinase SRK are required for the SI response. Although Arabidopsis thaliana acquired autogamy through loss of these genes, molecular evolution contributed to the spread of self-compatibility alleles requires further investigation. We show here that in this species, dominant SRK silencing genes have evolved at least twice. Different inverted repeat sequences were found in the relic SRK region of the Col-0 and C24 strains. Both types of inverted repeats suppress the functional SRK sequence in a dominant fashion with different target specificities. It is possible that these dominant suppressors of SI contributed to the rapid fixation of self-compatibility in A. thaliana.
Highlights
Selfing is a frequent evolutionary trend in angiosperms, and is a suitable model for studying the recurrent patterns underlying adaptive evolution
From the available genomic information archived in The Arabidopsis Information Resource (TAIR), we found an inverted repeat structure within the Col-0 allele of ψSRKA and named this structure SRKIRCol-0
We explored the involvement of inverted repeats in relic S-loci of A. thaliana in the suppression of S-locus receptor kinase (SRK) mRNA accumulation
Summary
Selfing is a frequent evolutionary trend in angiosperms, and is a suitable model for studying the recurrent patterns underlying adaptive evolution. Arabidopsis thaliana acquired autogamy through loss of these genes, molecular evolution contributed to the spread of self-compatibility alleles requires further investigation. 1234567890():,; Self-incompatibility (SI) refers to mechanisms that prevent self-fertilization and promote outcrossing between different individuals adopted by over 40% of flowering plant species[1]. In the Brassicaceae family, SI is controlled by two multi-allelic genes: the S-locus protein 11 (SP11; known as the S-locus cysteine-rich protein, SCR) and the S-locus receptor kinase (SRK)[2,3]. In the model plant species Arabidopsis thaliana, SC is considered to have evolved at least three times independently because three major haplogroups (A, B, and C) derived from a much larger set of diverged S haplotypes in the closely related outcrossers, such as A. halleri, are found[9].
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