Movement of plant viruses is delayed in a beta-1,3-glucanase-deficient mutant showing a reduced plasmodesmatal size exclusion limit and enhanced callose deposition

Plant J. 2000 Jan;21(2):157-66. doi: 10.1046/j.1365-313x.2000.00658.x.

Abstract

Susceptibility to virus infection is decreased in a class I beta-1,3-glucanase (GLU I)-deficient mutant (TAG4.4) of tobacco generated by antisense transformation. TAG4.4 exhibited delayed intercellular trafficking via plasmodesmata of a tobamovirus (tobacco mosaic virus), of a potexvirus (recombinant potato virus X expressing GFP), and of the movement protein (MP) 3a of a cucumovirus (cucumber mosaic virus). Monitoring the cell-to-cell movement of dextrans and peptides by a novel biolistic method revealed that the plasmodesmatal size exclusion limit (SEL) of TAG4.4 was also reduced from 1.0 to 0.85 nm. Therefore, GLU I-deficiency has a broad effect on plasmodesmatal movement, which is not limited to a particular virus type. Deposition of callose, a substrate for beta-1,3-glucanases, was increased in TAG4.4 in response to 32 degrees C treatment, treatment with the fungal elicitor xylanase, and wounding, suggesting that GLU I has an important function in regulating callose metabolism. Callose turnover is thought to regulate plasmodesmatal SEL. We propose that GLU I induction in response to infection may help promote MP-driven virus spread by degrading callose.

MeSH terms

  • Biological Transport
  • Glucan 1,3-beta-Glucosidase*
  • Glucans / genetics
  • Glucans / metabolism*
  • Glycoside Hydrolases / genetics
  • Glycoside Hydrolases / metabolism*
  • Microscopy, Fluorescence
  • Mutation
  • Plant Viral Movement Proteins
  • Plants, Toxic*
  • Potexvirus / pathogenicity*
  • Tobacco / genetics
  • Tobacco / metabolism
  • Tobacco / virology*
  • Tobamovirus / pathogenicity*
  • Viral Proteins / metabolism
  • Xylan Endo-1,3-beta-Xylosidase
  • Xylosidases / metabolism

Substances

  • Glucans
  • Plant Viral Movement Proteins
  • Viral Proteins
  • callose
  • Glycoside Hydrolases
  • Xylosidases
  • Xylan Endo-1,3-beta-Xylosidase
  • Glucan 1,3-beta-Glucosidase
  • beta-1,3-exoglucanase