Action of Multiple Cell Wall-Degrading Enzymes Is Required for Elicitation of Innate Immune Responses During Xanthomonas oryzae pv. oryzae Infection in Rice

Mol Plant Microbe Interact. 2016 Aug;29(8):599-608. doi: 10.1094/MPMI-02-16-0039-R. Epub 2016 Jul 19.

Abstract

Xanthomonas oryzae pv. oryzae secretes a number of plant cell wall-degrading enzymes (CWDEs) whose purified preparations induce defense responses in rice. These defense responses are suppressed by X. oryzae pv. oryzae using type 3 secretion system (T3SS) effectors and a type 3 secretion system mutant (T3SS(-)) of X. oryzae pv. oryzae is an inducer of rice defense responses. We assessed the role of individual CWDEs in induction of rice defense responses during infection, by mutating them in the genetic background of a T3SS(-). We mutated the genes for five different plant CWDEs secreted by X. oryzae pv. oryzae, including two cellulases (clsA and cbsA), one xylanase (xyn), one pectinase (pglA), and an esterase (lipA), singly in a T3SS(-) background. We have demonstrated that, as compared with a T3SS(-) of X. oryzae pv. oryzae, a cbsA(-)T3SS(-), a clsA(-)T3SS(-), and a xyn(-)T3SS(-) are deficient in induction of rice immune responses such as callose deposits and programmed cell death. In comparison, a lipA(-) T3SS(-) and a pglA(-)T3SS(-) is as efficient in induction of host defense responses as a T3SS(-). Overall, these results indicate that the collective action of X. oryzae pv. oryzae-secreted ClsA, CbsA, and Xyn proteins is required for induction of rice defense responses during infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Cell Wall / metabolism
  • Cellulases / genetics
  • Cellulases / metabolism
  • Endo-1,4-beta Xylanases / genetics
  • Endo-1,4-beta Xylanases / metabolism
  • Esterases / genetics
  • Esterases / metabolism
  • Glucans / metabolism
  • Host-Pathogen Interactions
  • Mutation
  • Oryza / immunology*
  • Oryza / microbiology
  • Plant Diseases / immunology*
  • Plant Diseases / microbiology
  • Plant Immunity*
  • Polygalacturonase / genetics
  • Polygalacturonase / metabolism
  • Sequence Analysis, DNA
  • Type III Secretion Systems
  • Xanthomonas / enzymology*
  • Xanthomonas / genetics
  • Xanthomonas / immunology

Substances

  • Bacterial Proteins
  • Glucans
  • Type III Secretion Systems
  • callose
  • Esterases
  • Cellulases
  • Polygalacturonase
  • Endo-1,4-beta Xylanases