Salicylic acid confers resistance to a biotrophic rust pathogen, Puccinia substriata, in pearl millet (Pennisetum glaucum)

Mol Plant Pathol. 2009 Mar;10(2):291-304. doi: 10.1111/j.1364-3703.2008.00532.x.

Abstract

Studies were undertaken to assess the induction of defence response pathways in pearl millet (Pennisetum glaucum) in response to infection with the leaf rust fungus Puccinia substriata. Pretreatment of pearl millet with salicylic acid (SA) conferred resistance to a virulent isolate of the rust fungus, whereas methyl jasmonate (MeJA) did not significantly reduce infection levels. These results suggest that the SA defence pathway is involved in rust resistance. In order to identify pearl millet genes that are specifically regulated in response to SA and not MeJA, and thus could play a role in resistance to P. substriata, gene expression profiling was performed. Substantial overlap in gene expression responses between the treatments was observed, with MeJA and SA treatments exhibiting 17% co-regulated transcripts. However, 34% of transcripts were differentially expressed in response to SA treatment, but not in response to MeJA treatment. SA-responsive transcripts represented genes involved in SA metabolism, defence response, signal transduction, protection from oxidative stress and photosynthesis. The expression profiles of pearl millet plants after treatment with SA or MeJA were more similar to one another than to the response during a compatible infection with P. substriata. However, some SA-responsive genes were repressed during P. substriata infection, indicating possible manipulation of host responses by the pathogen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / pharmacology
  • Basidiomycota / physiology*
  • Cluster Analysis
  • Cyclopentanes / pharmacology
  • DNA, Complementary / genetics
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant / drug effects
  • Genes, Plant
  • Immunity, Innate / drug effects*
  • Oligonucleotide Array Sequence Analysis
  • Oxylipins / pharmacology
  • Pennisetum / genetics
  • Pennisetum / microbiology*
  • Plant Diseases / genetics
  • Plant Diseases / immunology*
  • Plant Diseases / microbiology*
  • Plant Leaves / drug effects
  • Plant Leaves / microbiology
  • Salicylic Acid / pharmacology*

Substances

  • Acetates
  • Cyclopentanes
  • DNA, Complementary
  • Oxylipins
  • methyl jasmonate
  • Salicylic Acid