Metabolomics of Early Stage Plant Cell-Microbe Interaction Using Stable Isotope Labeling.

Qiuying Pang,Yang Wang,Sixue Chen,Xiufeng Yan,Qijie Guan,Wenwen Kong,Tong Zhang

doi:10.3389/fpls.2018.00760

Qiuying Pang, Yang Wang + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2018.00760

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Abstract

Metabolomics has been used in unraveling metabolites that play essential roles in plant–microbe (including pathogen) interactions. However, the problem of profiling a plant metabolome with potential contaminating metabolites from the coexisting microbes has been largely ignored. To address this problem, we implemented an effective stable isotope labeling approach, where the metabolome of a plant bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000 was labeled with heavy isotopes. The labeled bacterial cells were incubated with Arabidopsis thaliana epidermal peels (EPs) with guard cells, and excessive bacterial cells were subsequently removed from the plant tissues by washing. The plant metabolites were characterized by liquid chromatography mass spectrometry using multiple reactions monitoring, which can differentiate plant and bacterial metabolites. Targeted metabolomic analysis suggested that Pst DC3000 infection may modulate stomatal movement by reprograming plant signaling and primary metabolic pathways. This proof-of-concept study demonstrates the utility of this strategy in differentiation of the plant and microbe metabolomes, and it has broad applications in studying metabolic interactions between microbes and other organisms.

Highlights

Plant-microbe interactions involve a series of exchange of chemicals for signal perception, transduction, and metabolic responses
COR secretion by Pst DC3000 accumulated to a significantly high level at 1 h after incubation (Figure 1A), which is in line with previous observations that COR reopens the pathogenassociated molecular patterns (PAMPs)-triggered stomatal closure (Melotto et al, 2006; Panchal et al, 2016)
To test heavy COR secretion, heavy labeled Pst DC3000 were incubated with epidermal peels (EPs) for a total of 3 h

Summary

Introduction

Plant-microbe interactions involve a series of exchange of chemicals for signal perception, transduction, and metabolic responses. Plant cells detect pathogenassociated molecular patterns (PAMPs), which lead to the production of specialized metabolites such as phytoalexins to combat the pathogen invasion (Lin et al, 2014; Poloni and Schirawski, 2014; Arbona and Gomez-Cadenas, 2016). Past studies have demonstrated that reprograming of the primary metabolic pathways contributes to the plant defense against pathogens. Modulation of photosynthesis and other primary plant metabolic pathways such as amino acid and lipid metabolism has been associated with altered plant immune responses (Berger et al, 2007; Bolton, 2009; Rojas et al, 2014). The regulation in primary metabolism such as photosynthesis, assimilate partition and source-sink regulation, as well as the production of specialized metabolites in plant–pathogen interactions has become an emerging research topic.

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