Self-incompatibility requires GPI anchor remodeling by the poppy PGAP1 ortholog HLD1

Curr Biol. 2022 May 9;32(9):1909-1923.e5. doi: 10.1016/j.cub.2022.02.072. Epub 2022 Mar 21.


Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are tethered to the outer leaflet of the plasma membrane where they function as key regulators of a plethora of biological processes in eukaryotes. Self-incompatibility (SI) plays a pivotal role regulating fertilization in higher plants through recognition and rejection of "self" pollen. Here, we used Arabidopsis thaliana lines that were engineered to be self-incompatible by expression of Papaver rhoeas SI determinants for an SI suppressor screen. We identify HLD1/AtPGAP1, an ortholog of the human GPI-inositol deacylase PGAP1, as a critical component required for the SI response. Besides a delay in flowering time, no developmental defects were observed in HLD1/AtPGAP1 knockout plants, but SI was completely abolished. We demonstrate that HLD1/AtPGAP1 functions as a GPI-inositol deacylase and that this GPI-remodeling activity is essential for SI. Using GFP-SKU5 as a representative GPI-AP, we show that the HLD1/AtPGAP1 mutation does not affect GPI-AP production and targeting but affects their cleavage and release from membranes in vivo. Our data not only implicate GPI-APs in SI, providing new directions to investigate SI mechanisms, but also identify a key functional role for GPI-AP remodeling by inositol deacylation in planta.

Keywords: Arabidopsis; AtPGAP1; GPI-AP remodeling; GPI-inositol deacylase; HLD1; Papaver; pollen rejection; programmed cell death; self-incompatibility.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis* / metabolism
  • Glycosylphosphatidylinositols / genetics
  • Glycosylphosphatidylinositols / metabolism
  • Humans
  • Inositol / metabolism
  • Papaver* / genetics
  • Papaver* / metabolism
  • Pollen / metabolism


  • Glycosylphosphatidylinositols
  • Inositol