Mechanism of self/nonself-discrimination in Brassica self-incompatibility

Nat Commun. 2020 Oct 1;11(1):4916. doi: 10.1038/s41467-020-18698-w.

Abstract

Self-incompatibility (SI) is a breeding system that promotes cross-fertilization. In Brassica, pollen rejection is induced by a haplotype-specific interaction between pistil determinant SRK (S receptor kinase) and pollen determinant SP11 (S-locus Protein 11, also named SCR) from the S-locus. Although the structure of the B. rapa S9-SRK ectodomain (eSRK) and S9-SP11 complex has been determined, it remains unclear how SRK discriminates self- and nonself-SP11. Here, we uncover the detailed mechanism of self/nonself-discrimination in Brassica SI by determining the S8-eSRK-S8-SP11 crystal structure and performing molecular dynamics (MD) simulations. Comprehensive binding analysis of eSRK and SP11 structures reveals that the binding free energies are most stable for cognate eSRK-SP11 combinations. Residue-based contribution analysis suggests that the modes of eSRK-SP11 interactions differ between intra- and inter-subgroup (a group of phylogenetically neighboring haplotypes) combinations. Our data establish a model of self/nonself-discrimination in Brassica SI.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brassica rapa / physiology*
  • Crystallography
  • Flowers / metabolism
  • Haplotypes
  • Molecular Dynamics Simulation
  • Plant Breeding*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plant Proteins / ultrastructure
  • Pollen / metabolism
  • Protein Binding / physiology
  • Protein Domains / physiology
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Kinases / ultrastructure
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / ultrastructure
  • Sf9 Cells
  • Spodoptera

Substances

  • Plant Proteins
  • Recombinant Proteins
  • SP11 protein, Brassica
  • Protein Kinases
  • S-receptor kinase