Global Characterization of GH10 Family Xylanase Genes in Rhizoctonia cerealis and Functional Analysis of Xylanase RcXYN1 During Fungus Infection in Wheat.

Lin Lu,Zengyan Zhang,Yongwei Liu

doi:10.3390/ijms21051812

Abstract

Wheat (Triticum aestivum L.) is an important staple crop. Rhizoctonia cerealis is the causal agent of diseases that are devastating to cereal crops, including wheat. Xylanases play an important role in pathogenic infection, but little is known about xylanases in R. cerealis. Herein, we identified nine xylanase-encoding genes from the R. cerealis genome, named RcXYN1–RcXYN9, examined their expression patterns, and investigated the pathogenicity role of RcXYN1. RcXYN1–RcXYN9 proteins contain two conserved glutamate residues within the active motif in the glycoside hydrolase 10 (GH10) domain. Of them, RcXYN1–RcXYN4 are predicted to be secreted proteins. RcXYN1–RcXYN9 displayed different expression patterns during the infection process of wheat, and RcXYN1, RcXYN2, RcXYN5, and RcXYN9 were expressed highly across all the tested inoculation points. Functional dissection indicated that the RcXYN1 protein was able to induce necrosis/cell-death and H2O2 generation when infiltrated into wheat and Nicotiana benthamiana leaves. Furthermore, application of RcXYN1 protein followed by R. cerealis led to significantly higher levels of the disease in wheat leaves than application of the fungus alone. These results demonstrate that RcXYN1 acts as a pathogenicity factor during R. cerealis infection in wheat. This is the first investigation of xylanase genes in R. cerealis, providing novel insights into the pathogenesis mechanisms of R. cerealis.

Highlights

Wheat (Triticum aestivum L.) is one of the most important staple crops worldwide
Nine glycoside hydrolase 10 (GH10) domain-containing xylanase proteins were identified in the proteome predicted from the R. cerealis genome sequence
In this study, we identified a total of nineGH10 family xylanases from the sequenced R. cerealis genome, characterized their gene structures and expression patterns, and investigated their possible roles in fungal pathogenicity

Summary

Introduction

Wheat (Triticum aestivum L.) is one of the most important staple crops worldwide. Its highly efficient production is necessary for global food security [1]. The necrotrophic fungus Rhizoctonia cerealis van der Hoeven, belonging to the binucleate Rhizoctonia subgroup AG-D I [3], is the causal agent of sharp eyespot, a disease mainly found on the stem base of wheat plants. Since the late 1990s, China has become the largest epidemic region, where more than 6.67 million hectares of wheat plants can be infected by R. cerealis annually [6,7,8]. The fungus can infect other important economical crops and bio-energy plants, causing root rot disease in sugar beet, cotton, potato, and several legumes, and yellow patch in turf grasses [11,12]. To efficiently improve resistance of wheat and other plants to R. cerealis, it is necessary to explore the pathogenesis mechanism during the fungus–plant interactions

Methods

Results

Conclusion