Molecular Insights into the Role of Cysteine-Rich Peptides in Induced Resistance to Fusarium oxysporum Infection in Tomato Based on Transcriptome Profiling

Abstract

Cysteine-rich peptides (CRPs) play an important role in plant physiology. However, their role in resistance induced by biogenic elicitors remains poorly understood. Using whole-genome transcriptome sequencing and our CRP search algorithm, we analyzed the repertoire of CRPs in tomato Solanum lycopersicum L. in response to Fusarium oxysporum infection and elicitors from F. sambucinum. We revealed 106 putative CRP transcripts belonging to different families of antimicrobial peptides (AMPs), signaling peptides (RALFs), and peptides with non-defense functions (Major pollen allergen of Olea europaea (Ole e 1 and 6), Maternally Expressed Gene (MEG), Epidermal Patterning Factor (EPF)), as well as pathogenesis-related proteins of families 1 and 4 (PR-1 and 4). We discovered a novel type of 10-Cys-containing hevein-like AMPs named SlHev1, which was up-regulated both by infection and elicitors. Transcript profiling showed that F. oxysporum infection and F. sambucinum elicitors changed the expression levels of different overlapping sets of CRP genes, suggesting the diversification of functions in CRP families. We showed that non-specific lipid transfer proteins (nsLTPs) and snakins mostly contribute to the response of tomato plants to the infection and the elicitors. The involvement of CRPs with non-defense function in stress reactions was also demonstrated. The results obtained shed light on the mode of action of F. sambucinum elicitors and the role of CRP families in the immune response in tomato.

Synthetic Oligopeptides Mimicking γ-Core Regions of Cysteine-Rich Peptides of Solanum lycopersicum Possess Antimicrobial Activity against Human and Plant Pathogens

“…It has been generally acknowledged that the antimicrobial activity of plant AMPs is associated with their γ-core motifs, which are short sequences with a GXCX 3-9 C signature adopting a β-hairpin structure [15,16]. Tomato CRPs discovered in transcriptomes of plants infected by F. oxysporum and treated with F. sambucinum elicitors [11] were screened for the presence of γ-core sequences. The γ-core motifs were discovered in DEFLs, snakins, nsLTPs and MEG peptides.…”

“…Nine DEFL sequences were discovered in transcriptomes of tomato plants infected with F. oxysporum, treated with F. sambucinum elicitors and infected after elicitor treatment [11]. Of them, only three DEFL genes were responsive to F. oxysporum infection or elicitor treatment.…”

“…With the advent of high-throughput sequencing, dozens and even hundreds of AMP-like sequences have been discovered in plant genomes [5][6][7]. Whole transcriptome analysis showed that complex arrays of AMPs are involved in response to pathogens and resistance-inducing agents [8][9][10][11]. Both pathogens and elicitors trigger expression of different sets of AMP-like genes, which prevent or impede colonization of plant tissues in combination with other antimicrobial proteins and secondary metabolites.…”

“…Both pathogens and elicitors trigger expression of different sets of AMP-like genes, which prevent or impede colonization of plant tissues in combination with other antimicrobial proteins and secondary metabolites. In addition to AMPs, environmental stress affects expression of other cysteine-rich peptides (CRPs) [11], whose role in the immune response is less well understood.…”

“…In our previous studies, we explored transcriptional changes in CRP genes in Solanum lycopersicum L. plants infected with Fusarium oxysporum strain F37 and treated with biogenic elicitors isolated from the non-pathogenic FS-94 strain of F. sambucinum. We identified CRP genes which were up-regulated by the pathogen and the elicitors [11]; they encoded defensin-like (DEFL) peptides, snakins, non-specific lipid-transfer proteins (nsLTPs) and MEG (Maternally Expressed Gene) peptides. In this work, nine CRP peptides discovered in tomato transcriptomes were selected for functional studies.…”