In roots of Arabidopsis thaliana, the damage-associated molecular pattern AtPep1 is a stronger elicitor of immune signalling than flg22 or the chitin heptamer

Abstract

Plants interpret their immediate environment through perception of small molecules. Microbe-associated molecular patterns (MAMPs) such as flagellin and chitin are likely to be more abundant in the rhizosphere than plant-derived damage-associated molecular patterns (DAMPs). We investigated how the Arabidopsis thaliana root interprets MAMPs and DAMPs as danger signals. We monitored root development during exposure to increasing concentrations of the MAMPs flg22 and the chitin heptamer as well as of the DAMP AtPep1. The tissue-specific expression of defence-related genes in roots was analysed using a toolkit of promoter::YFPN lines reporting jasmonic acid (JA)-, salicylic acid (SA)-, ethylene (ET)- and reactive oxygen species (ROS)- dependent signalling. Finally, marker responses were analysed during invasion by the root pathogen Fusarium oxysporum. The DAMP AtPep1 triggered a stronger activation of the defence markers compared to flg22 and the chitin heptamer. In contrast to the tested MAMPs, AtPep1 induced SA- and JA-signalling markers in the root and caused a severe inhibition of root growth. Fungal attack resulted in a strong activation of defence genes in tissues close to the invading fungal hyphae. The results collectively suggest that AtPep1 presents a stronger danger signal to the Arabidopsis root than the MAMPs flg22 and chitin heptamer.

A dual function of the IDA peptide in regulating cell separation and modulating plant immunity at the molecular level

“…The spatial onset of the Ca 2+ response in mIDA treated roots correlated with the spatial expression pattern of pMYB51:YFPN in mIDA treated roots ( Fig. 1c) which differed from that previously reported for the flg22 elicited response 27 . These observations indicate differences in tissue specificity of immune responses between mIDA and flg22 which are likely to depend on the cellular distribution of their cognate receptors.…”

“…The expression of MYB51, a WRKY target gene, has previously been shown to increase in response to flg22 26 resulting in biosynthesis of the secondary metabolite indolic glucosinolates which plays a role in defense. To investigate whether IDA could regulate a similar set of genes induced by flg22 we looked at roots expressing the promoter-driven nuclear localized YFP lines of MYB51 (pMYB51:YFPN) 27 treated with a highly active synthetic IDA peptide 12 (from here on referred to as mIDA). The fluorescent signal of the reporter was analyzed in the root tip/meristematic zone and an enhanced expression of MYB51 was predominantly detected in the meristematic zone after 7 hours (h) of mIDA treatment compared to a non-treated control ( Fig.…”

AnArabidopsislong noncoding RNA modulates the transcriptome through interactions with a network of splicing factors

“…It is known that peptides corresponding to the most conserved domains of eubacterial flagellins (flg) act as potent elicitors in A. thaliana. Notably, flg22 causes callose deposition, induction of genes encoding for pathogenesis-related proteins and a strong inhibition of growth, including root development (Gomez-Gomez et al, 1999;Beck et al, 2014;Poncini et al, 2017). Thus, we first assessed the transcriptional behavior over time of ASCO in response to flg22.…”

Cell type identity determines transcriptomic immune responses inArabidopsis thalianaroots

“…Leaves, for instance, elicited with the MAMP flg22 (the active epitope of bacterial flagellin, recognised by the PRR FLS2) activate PTI responses including the rapid production of reactive oxygen species (ROS burst), MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) phosphorylation and induction of immunity genes to stop pathogen infection (Felix et al, 1999; Gómez-Gómez et al, 1999; Asai et al, 2002; Zipfel et al, 2004). Similarly, root cells recognise MAMPs such as flg22 by FLAGELLIN SENSITIVE 2 (FLS2) to trigger effective PTI (Millet et al, 2010; Jacobs et al, 2011; Beck et al, 2014; Wyrsch et al, 2015; Poncini et al, 2017). In addition to MAMPs, plants produce damage-associated molecular patterns (DAMPs) upon pathogen recognition as part of PTI.…”

“…PEPR1/2-triggered immune signalling was further shown to maintain PTI in plants lacking MAMP perception and signalling components (Tintor et al, 2013; Yamada et al, 2016). Accordingly, comparative analyses of flg22 and Pep1 activity in roots, while demonstrating typical PTI responses, Pep1 was a more potent elicitor of immunity (Poncini et al, 2017). While all these studies highlight apparent differences and interdependencies between flg22 and Pep1-induced PTI in Arabidopsis the gene network defining DAMP and MAMP-mediated PTI in roots is currently unknown.…”