The Fusarium graminearum FGSG_03624 Xylanase Enhances Plant Immunity and Increases Resistance against Bacterial and Fungal Pathogens.

Silvio Tundo,Valentina Bigini,Francesco Favaron,Franco Faoro,Daniel V Savatin,Maria Chiara Paccanaro,Luca Sella

doi:10.3390/ijms221910811

Silvio Tundo, Valentina Bigini + Show 5 more

Open Access

https://doi.org/10.3390/ijms221910811

Copy DOI

Abstract

Fungal enzymes degrading the plant cell wall, such as xylanases, can activate plant immune responses. The Fusarium graminearum FGSG_03624 xylanase, previously shown to elicit necrosis and hydrogen peroxide accumulation in wheat, was investigated for its ability to induce disease resistance. To this aim, we transiently and constitutively expressed an enzymatically inactive form of FGSG_03624 in tobacco and Arabidopsis, respectively. The plants were challenged with Pseudomonas syringae pv. tabaci or pv. maculicola and Botrytis cinerea. Symptom reduction by the bacterium was evident, while no reduction was observed after B. cinerea inoculation. Compared to the control, the presence of the xylanase gene in transgenic Arabidopsis plants did not alter the basal expression of a set of defense-related genes, and, after the P. syringae inoculation, a prolonged PR1 expression was detected. F. graminearum inoculation experiments of durum wheat spikes exogenously treated with the FGSG_03624 xylanase highlighted a reduction of symptoms in the early phases of infection and a lower fungal biomass accumulation than in the control. Besides, callose deposition was detected in infected spikes previously treated with the xylanase and not in infected control plants. In conclusion, our results highlight the ability of FGSG_03624 to enhance plant immunity, thus decreasing disease severity.

Highlights

Fusarium Head Blight (FHB) is a global crop disease with a great economic impact on the cereal industry [1,2]
To investigate a possible induction of disease resistance, the previously characterized and heterologously expressed Xyl [18] was sprayed on Arabidopsis plants, and, 4 days after the treatment, the plants were inoculated with P. syringae pv. maculicola or B. cinerea
Compared to control leaves sprayed with water only, in the xylanase treated leaves, the size of the bacterial-induced spots at 3 dpi and 6 dpi was significantly reduced by 25%

Summary

Introduction

Fusarium Head Blight (FHB) is a global crop disease with a great economic impact on the cereal industry [1,2]. Different Fusarium species are associated with the disease, but Fusarium graminearum is the most common causal agent in cereal crops, especially wheat [5]. The timing of secretion of these enzymes suggests that CWDEs facilitate rapid colonization of spike tissues through the degradation of the cell wall, which represents the first physical barrier against pathogens. The importance of these enzymes in the infection process is supported by the evidence that the overexpression in transgenic wheat plants of protein inhibitors of CWDEs resulted in reduced symptoms of FHB [7,8,9,10]

Methods

Results

Conclusion