Functional test of Brassica self-incompatibility modifiers in Arabidopsis thaliana

Hiroyasu Kitashiba, Pei Liu, Takeshi Nishio, June B. Nasrallah, Mikhail E. Nasrallah

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51 Citations (Scopus)


The self-incompatibility (SI) system of the Brassicaceae is based on allele-specific interactions among haplotypes of the S locus. In all tested self-incompatible Brassicaceae, the S haplotype encompasses two linked genes, one encoding the S-locus receptor kinase (SRK), a transmembrane kinase displayed at the surface of stigma epidermal cells, and the other encoding its ligand, the S-locus cysteine- rich (SCR) protein, which is localized in the pollen coat. Transfer of the two genes to self-fertile Arabidopsis thaliana allowed the establishment of robust SI in several accessions, indicating that the signaling cascade triggered by this receptor-ligand interaction and the resulting inhibition of "self" pollen by the stigma have been maintained in extant A. thaliana. Based on studies in Brassica species, the membrane-tethered kinase MLPK, the ARM repeatcontaining U-box protein ARC1, and the exocyst subunit Exo70A1 have been proposed to function as components of an SI signaling cascade. Here we tested the role of these molecules in the SI response of A. thaliana SRK-SCR plants. We show that the A. thaliana ARC1 ortholog is a highly decayed pseudogene. We also show that, unlike reports in Brassica, inactivation of the MLPK ortholog AtAPK1b and overexpression of Exo70A1 neither abolish nor weaken SI in A. thaliana SRK-SCR plants. These results do not support a role for these molecules in the SI response of A. thaliana.

Original languageEnglish
Pages (from-to)18173-18178
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number44
Publication statusPublished - 2011 Nov 1
Externally publishedYes


  • Receptor signaling
  • S locus receptor kinase

ASJC Scopus subject areas

  • General


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