A comparison of PTI defense profiles induced in Solanum tuberosum by PAMP and non-PAMP elicitors shows distinct, elicitor-specific responses

PLoS One. 2020 Aug 12;15(8):e0236633. doi: 10.1371/journal.pone.0236633. eCollection 2020.

Abstract

The induction of general plant defense responses following the perception of external elicitors is now regarded as the first level of the plant immune response. Depending on the involvement or not of these molecules in pathogenicity, this induction of defense is called either Pathogen-Associated Molecular Pattern (PAMP) Triggered Immunity or Pattern Triggered Immunity-both abbreviated to PTI. Because PTI is assumed to be a widespread and stable form of resistance to infection, understanding the mechanisms driving it becomes a major goal for the sustainable management of plant-pathogen interactions. However, the induction of PTI is complex. Our hypotheses are that (i) the recognition by the plant of PAMPs vs non-PAMP elicitors leads to specific defense profiles and (ii) the responses specifically induced by PAMPs target critical life history traits of the pathogen that produced them. We thus analyzed, using a metabolomic approach coupled with transcriptomic and hormonal analyses, the defense profiles induced in potato foliage treated with either a Concentrated Culture Filtrate (CCF) from Phytophthora infestans or two non-PAMP preparations, β-aminobutyric acid (BABA) and an Ulva spp. Extract, used separately. Each elicitor induced specific defense profiles. CCF up-regulated sesquiterpenes but down-regulated sterols and phenols, notably α-chaconine, caffeoyl quinic acid and rutin, which decreased spore production of P. infestans in vitro. CCF thus induces both defense and counter-defense responses. By contrast, the Ulva extract triggered the synthesis of a large-spectrum of antimicrobial compounds through the phenylpropanoid/flavonoid pathways, while BABA targeted the primary metabolism. Hence, PTI can be regarded as a heterogeneous set of general and pathogen-specific responses triggered by the molecular signatures of each elicitor, rather than as a uniform, non-specific and broad-spectrum set of general defense reactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminobutyrates / pharmacology
  • Disease Resistance / drug effects
  • Disease Resistance / immunology*
  • Flavonoids / biosynthesis
  • Gene Expression Regulation, Plant / drug effects
  • Host-Pathogen Interactions / genetics
  • Host-Pathogen Interactions / immunology
  • Phenols / metabolism
  • Phytophthora infestans / immunology
  • Phytophthora infestans / pathogenicity
  • Plant Diseases / immunology*
  • Plant Diseases / microbiology
  • Plant Extracts / chemistry
  • Plant Extracts / pharmacology
  • Plant Immunity / drug effects
  • Plant Immunity / immunology*
  • Sesquiterpenes / metabolism
  • Solanum tuberosum / growth & development
  • Solanum tuberosum / immunology*
  • Solanum tuberosum / microbiology
  • Sterols / metabolism
  • Ulva / chemistry

Substances

  • Aminobutyrates
  • Flavonoids
  • Phenols
  • Plant Extracts
  • Sesquiterpenes
  • Sterols
  • 3-aminobutyric acid

Grants and funding

RLM is supported by a CIFRE PhD grant from Centre Mondial de l'Innovation-Roullier (France) and ANRT-Association Nationale Recherche Technologie (France).