Spatiotemporal Changes in Xylan-1/Xyloglucan and Xyloglucan Xyloglucosyl Transferase (XTH-Xet5) as a Step-In of Ultrastructural Cell Wall Remodelling in Potato⁻Potato Virus Y (PVYNTN) Hypersensitive and Susceptible Reaction.

Katarzyna Otulak-Kozieł,Edmund Kozieł,Józef Bujarski

doi:10.3390/ijms19082287

Abstract

One type of monitoring system in a plant cell is the cell wall, which intensively changes its structure during interaction with pathogen-stress factors. The wall plays a role as a dynamic and controlled structure, although it is not fully understood how relevant these modifications are to the molecular mechanisms during plant–virus interactions. In this work we localise the non-cellulosic polysaccharides such as xyloglucan, xylan (xylan-1) and xyloglucosyl transferase (XTH-Xet5), the enzyme that participates in the metabolism of xyloglucan. This provided us with information about the in situ distribution of the components of the hemicellulotic cell wall matrix in hypersensitive and susceptible potato–PVYNTN interactions. The loosening of the cell wall was accompanied by an increase in xylan depositions during susceptible interactions, whereas, during the hypersensitive response, when the cell wall was reinforced, the xylan content decreased. Moreover, the PVY inoculation significantly redirected XTH-Xet5 depositions, regardless of types of interactions, compared to mock-inoculated tissues. Furthermore, the immunogold localisation clearly revealed the domination of Xet5 in the cell wall and in vesicles in the susceptible host. In contrast, in the resistant host increased levels of Xet5 were observed in cytoplasm, in the cell wall and in the trans-Golgi network. These findings show that the hypersensitive reaction activated XTH-Xet5 in the areas of xyloglucan endo-transglycosylase (XET) synthesis, which was then actively transported to cytoplasm, cell wall and to vacuoles. Our results provide novel insight into cell wall reorganisation during PVYNTN infection as a response to biotic stress factors. These novel findings help us to understand the mechanisms of defence responses that are incorporated into the cell wall signalling network.

Highlights

Plant virus diseases are a major threat to crop production around the world
In the present research we studied the localisation of xylan-1 (CCRC-M108) and XTH-Xet5 at four time points during PVYNTN–potato compatible and incompatible interactions
In this work we have addressed a general question about the function of different cell wall components—how these elements interact with each other, and how they change due to interactions with pathogenic viruses

Summary

Introduction

Plant virus diseases are a major threat to crop production around the world. Viruses are widely known as a large, highly various and economically important group of plant pathogens, and are the source of an enormous amount of pathological changes in plant tissues [1]. One of the most important plant viruses, Potato Y virus (PVY, genus Potyvirus, family Potyviridae), has been categorised as the fifth most economically damaging virus worldwide [2]. Among the PVY strains, a whole variety of symptoms of infection are possible, from leaf crinkling to necrosis, and they hardly depend on the virus strain or the level of resistance. The recombinant strains like PVYNTN or PVYN-Wi usually induce mild or transient foliar mosaic symptoms, they are more likely to cause potato tuber necrotic ringspot disease (PTNRD) of varying severity in numerous potato cultivars

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