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Summary 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 inArabidopsis thaliana. The best candidate AtSTP8 was further characterised for its transport properties inSaccharomyces cerevisiaeand 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 inS. cerevisiaesuggested that AtSTP8 can transport a broad spectrum of hexose substrates. Moreover, transgenic Arabidopsis plants overexpressingAtSTP8showed 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.
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bZIP60 and Bax inhibitor 1 contribute IRE1 ‐dependent and independent roles to potexvirus infection
Summary IRE1, BI‐1, and bZIP60 monitor compatible plant–potexvirus interactions though recognition of the viral TGB3 protein. This study was undertaken to elucidate the roles of threeIRE1isoforms, thebZIP60UandbZIP60S, andBI‐1roles in genetic reprogramming of cells during potexvirus infection.Experiments were performed usingArabidopsis thalianaknockout lines andPlantago asiatica mosaic virusinfectious clone tagged with the green fluorescent protein gene (PlAMV‐GFP).There were more PlAMV‐GFP infection foci inire1a/b,ire1c,bzip60, andbi‐1knockout than wild‐type (WT) plants. Cell‐to‐cell movement and systemic RNA levels were greaterbzip60andbi‐1than in WT plants. Overall, these data indicate an increased susceptibility to virus infection. Transgenic overexpression ofAtIRE1borStbZIP60inire1a/borbzip60mutant background reduced virus infection foci, whileStbZIP60expression influences virus movement. Transgenic overexpression ofStbZIP60also confers endoplasmic reticulum (ER) stress resistance following tunicamycin treatment. We also show bZIP60U and TGB3 interact at the ER.This is the first demonstration of a potatobZIPtranscription factor complementing genetic defects in Arabidopsis. Evidence indicates that the three IRE1 isoforms regulate the initial stages of virus replication and gene expression, while bZIP60 and BI‐1 contribute separately to virus cell‐to‐cell and systemic movement.
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- Award ID(s):
- 2038872
- PAR ID:
- 10520722
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 243
- Issue:
- 3
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 1172-1189
- Size(s):
- p. 1172-1189
- Sponsoring Org:
- National Science Foundation
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