Plant Elicitor Peptide (Pep) Signaling and Pathogen Defense in Tomato

Abstract

Endogenous signaling compounds are intermediaries in signaling pathways that plants use to respond to the perception of harmful and beneficial organisms. The plant elicitor peptides (Peps) of plants are important endogenous signaling molecules that induce elements of defense responses such as hormone production, increased expression of defensive genes, the activation of phosphorelays, and the induction of cell secondary messenger synthesis. The processes by which Peps confer resistance to pathogenic microorganisms have been extensively studied in Arabidopsis but are less known in crop plants. Tomato and many other solanaceous plants have an endogenous signaling polypeptide, systemin, that is involved in the defense against herbivorous insects and necrotrophic pathogens. This paper explores the similarity of the effects and chemical properties of Pep and systemin in tomato. Additionally, the relationship of the Pep receptor and systemin receptors is explored, and the identification of a second tomato Pep receptor in the literature is called into question. We suggest future directions for research on Pep signaling in solanaceous crops during interactions with microbes.

Transcriptome-Wide Identification and Expression Analysis of Genes Encoding Defense-Related Peptides of Filipendula ulmaria in Response to Bipolaris sorokiniana Infection

“…Mature Peps of different plant species contain family-specific motifs [97,98]. Peps act as DAMPs (Damage-Associated Molecular Patterns) eliciting plant PTI responses, such as the production of reactive oxygen species, phosphorylation of MAP kinases, changes in defense gene expression, and deposition of callose in cell walls, ultimately resulting in resistance against diverse pathogens [69,96,[99][100][101][102]. Peps were also shown to increase abiotic stress tolerance in plants [103].…”

Bioassays for Identifying and Characterizing Plant Regulatory Peptides

“…Remarkably, the early-discovered plant regulatory peptides continue to be actively investigated and hold substantial applied potential. Prominent examples include cell proliferation regulators like the 5-amino acid PSK (phytosulfokine) [7,8] and the 18-amino acid peptide PSY1 (Plant peptide containing sulfated tyrosine 1) [9,10]; defense peptides like systemin [11][12][13][14][15][16][17], the 18-amino acid HypSys (hydroxyproline-rich systemin) [18,19], AtPep1, the 23-amino acid peptide isolated from extracts of Arabidopsis leaves, exhibiting characteristics of an endogenous elicitor of the innate immune response [20][21][22][23][24][25][26], and the 49-amino acid RALF peptide (Rapid alkalinization factor) [27,28]; apical meristem regulator, the 12-amino acid peptide CLV3 (CLAVATA3) [29][30][31][32], and other members of the CLE (CLAVATA3/EMBRYO SURROUNDING REGION-related) [30] peptide family such as the 12-amino acid vascular stem cell differentiation factors TDIF and CLE41/44 [33,34] and root growth regulator CEP1 [34,35] (Table 1). The biological activity of hundreds of newly isolated and putative plant peptides remains uncharacterized.…”