Self-incompatibility in the genus Arabidopsis: characterization of the S locus in the outcrossing A. lyrata and its autogamous relative A. thaliana.
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 approximately 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.
Kusaba
M
M
Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA.
Dwyer
K
K
Hendershot
J
J
Vrebalov
J
J
Nasrallah
J B
JB
Nasrallah
M E
ME
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D001937:Brassica / Q000235:genetics*; D019607:Brassicaceae / Q000235:genetics; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003434:Crossing Over, Genetic; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D017343:Genes, Plant; D006023:Glycoproteins; D006239:Haplotypes; D019901:Locus Control Region; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism*; D011058:Pollen / Q000502:physiology; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011494:Protein Kinases; D011994:Recombinant Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D006023:Glycoproteins; D010940:Plant Proteins; D011994:Recombinant Proteins; C401308:SCR protein, Brassica oleracea; C064156:self-incompatibility locus specific glycoprotein, Brassica; D011494:Protein Kinases; C079832:S-receptor kinase