The rare sugar D-allose acts as a triggering molecule of rice defence via ROS generation

J Exp Bot. 2013 Nov;64(16):4939-51. doi: 10.1093/jxb/ert282. Epub 2013 Sep 7.

Abstract

Only D-allose, among various rare monosaccharides tested, induced resistance to Xanthomonas oryzae pv. oryzae in susceptible rice leaves with defence responses: reactive oxygen species, lesion mimic formation, and PR-protein gene expression. These responses were suppressed by ascorbic acid or diphenylene iodonium. Transgenic rice plants overexpressing OsrbohC, encoding NADPH oxidase, were enhanced in sensitivity to D-allose. D-Allose-mediated defence responses were suppressed by the presence of a hexokinase inhibitor. 6-Deoxy-D-allose, a structural derivative of D-allose unable to be phosphorylated, did not confer resistance. Transgenic rice plants expressing Escherichia coli AlsK encoding D-allose kinase to increase D-allose 6-phosphate synthesis were more sensitive to D-allose, but E. coli AlsI encoding D-allose 6-phosphate isomerase expression to decrease D-allose 6-phosphate reduced sensitivity. A D-glucose 6-phosphate dehydrogenase-defective mutant was also less sensitive, and OsG6PDH1 complementation restored full sensitivity. These results reveal that a monosaccharide, D-allose, induces rice resistance to X. oryzae pv. oryzae by activating NADPH oxidase through the activity of D-glucose 6-phosphate dehydrogenase, initiated by hexokinase-mediated conversion of D-allose to D-allose 6-phosphate, and treatment with D-allose might prove to be useful for reducing disease development in rice.

Keywords: NADPH oxidase; Oryza sativa L; d-Allose; d-glucose 6-phosphate dehydrogenase; hexokinase; rare sugar..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Gene Expression Regulation, Plant
  • Glucose / immunology*
  • NADPH Oxidases / genetics
  • NADPH Oxidases / immunology
  • Oryza / genetics*
  • Oryza / metabolism
  • Oryza / microbiology
  • Plant Diseases / immunology
  • Plant Diseases / microbiology
  • Plant Proteins / genetics
  • Plant Proteins / immunology
  • Reactive Oxygen Species / immunology*
  • Xanthomonas / physiology

Substances

  • Plant Proteins
  • Reactive Oxygen Species
  • allose
  • NADPH Oxidases
  • Glucose