AtSTP8, an endoplasmic reticulum-localised monosaccharide transporter from Arabidopsis, is recruited to the extrahaustorial membrane during powdery mildew infection

New Phytol. 2021 Jun;230(6):2404-2419. doi: 10.1111/nph.17347. Epub 2021 Apr 3.


Biotrophic pathogens are believed to strategically manipulate sugar transport in host cells to enhance their access to carbohydrates. However, mechanisms of sugar translocation from host cells to biotrophic fungi such as powdery mildew across the plant-haustorium interface remain poorly understood. To investigate this question, systematic subcellular localisation analysis was performed for all the 14 members of the monosaccharide sugar transporter protein (STP) family in Arabidopsis thaliana. The best candidate AtSTP8 was further characterised for its transport properties in Saccharomyces cerevisiae and potential role in powdery mildew infection by gene ablation and overexpression in Arabidopsis. Our results showed that AtSTP8 was mainly localised to the endoplasmic reticulum (ER) and appeared to be recruited to the host-derived extrahaustorial membrane (EHM) induced by powdery mildew. Functional complementation assays in S. cerevisiae suggested that AtSTP8 can transport a broad spectrum of hexose substrates. Moreover, transgenic Arabidopsis plants overexpressing AtSTP8 showed increased hexose concentration in leaf tissues and enhanced susceptibility to powdery mildew. Our data suggested that the ER-localised sugar transporter AtSTP8 may be recruited to the EHM where it may be involved in sugar acquisition by haustoria of powdery mildew from host cells in Arabidopsis.

Keywords: Arabidopsis thaliana; endoplasmic reticulum; extrahaustorial membrane; haustorium; powdery mildew; sugar transport protein.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis Proteins* / genetics
  • Arabidopsis* / genetics
  • Ascomycota*
  • Endoplasmic Reticulum
  • Host-Pathogen Interactions
  • Monosaccharides
  • Plant Diseases
  • Saccharomyces cerevisiae


  • Arabidopsis Proteins
  • Monosaccharides