The Modification of Plant Cell Wall Polysaccharides in Potato Plants during Pectobacterium atrosepticum-Caused Infection

Vladimir Gorshkov,Ivan Tsers,Yuri Gogolev,Olga Petrova,Polina Mikshina,Bakhtiyar Islamov,Tatyana Gorshkova,Natalia Gogoleva,Olga Gogoleva,Marina Ageeva,Olga Parfirova

doi:10.3390/plants10071407

Abstract

Our study is the first to consider the changes in the entire set of matrix plant cell wall (PCW) polysaccharides in the course of a plant infectious disease. We compared the molecular weight distribution, monosaccharide content, and the epitope distribution of pectic compounds and cross-linking glycans in non-infected potato plants and plants infected with Pectobacterium atrosepticum at the initial and advanced stages of plant colonization by the pathogen. To predict the gene products involved in the modification of the PCW polysaccharide skeleton during the infection, the expression profiles of potato and P. atrosepticum PCW-related genes were analyzed by RNA-Seq along with phylogenetic analysis. The assemblage of P. atrosepticum biofilm-like structures—the bacterial emboli—and the accumulation of specific fragments of pectic compounds that prime the formation of these structures were demonstrated within potato plants (a natural host of P. atrosepticum). Collenchyma was shown to be the most “vulnerable” tissue to P. atrosepticum among the potato stem tissues. The infection caused by the representative of the Soft Rot Pectobacteriaceae was shown to affect not only pectic compounds but also cross-linking glycans; the content of the latter was increased in the infected plants compared to the non-infected ones.

Highlights

IntroductionThe structure of the polysaccharide skeleton of the plant cell wall (PCW) undergoes a transformation during infectious diseases, since most (if not all) phytopathogens produce extracellular enzymes degrading PCW polysaccharides and/or proteins (e.g., expansins) that disturb the interaction between different polysaccharides
We have shown that the initiation of pectin modification starts in the asymptomatic zone, where huge pectic molecules of >1500 kDa present in control plants are disintegrated to fragments of
In our previous study on tobacco plants, based on RNA-Seq data, we have proposed that the observed upregulation of xyloglucan endotransglycosylases/hydrolases (XTH)- and expansin-encoding genes during Pectobacterium atrosepticum (Pba)-caused infection might promote the release of rhamnogalacturonan I (RG-I) fragments from the PCW and facilitate PCW degradation by increasing the availability of polymers to the corresponding enzymes [13]

Summary

Introduction

The structure of the polysaccharide skeleton of the PCW undergoes a transformation during infectious diseases, since most (if not all) phytopathogens produce extracellular enzymes degrading PCW polysaccharides and/or proteins (e.g., expansins) that disturb the interaction between different polysaccharides. Many phytopathogens were shown to exploit PCW enzymes and proteins of the host plant to cause PCW loosening mediated by the host itself [4,5,6]. To the best of our knowledge, no comprehensive studies on the modification of the whole PCW polysaccharide ensemble within the infected plant were performed for any infectious disease except for the investigation of pectin destruction in tobacco plants after infection with Pectobacterium atrosepticum (Pba) [10]

Objectives

Methods

Results

Discussion

Conclusion