Characterization of histological changes at the tillering stage (Z21) in resistant and susceptible wheat plants infected by Tilletia controversa K\xfchn

Tongshuo Xu,Wanquan Chen,Ghulam Muhae Ud Din,Taiguo Liu,Li Gao,Dandan Qin

doi:10.1186/s12870-020-02819-0

Tongshuo Xu, Wanquan Chen + Show 4 more

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https://doi.org/10.1186/s12870-020-02819-0

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Abstract

BackgroundDwarf bunt, which is caused by Tilletia controversa Kühn, is a soilborne and seedborne disease that occurs worldwide and can lead to 70% or even total losses of wheat crops. However, very little information is available about the histological changes that occur in dwarf bunt-resistant and dwarf bunt-susceptible wheat plants at the tillering stage (Z21). In this study, we used scanning electron microscopy and transmission electron microscopy to characterize the histological changes at this stage in resistant and susceptible wheat cultivars infected by T. controversa.ResultsUsing scanning electron microscopy, the root, stem, and leaf structures of resistant and susceptible cultivars were examined after T. controversa infection. The root epidermal and vascular bundles were more severely damaged in the susceptible T. controversa-infected plants than in the resistant plants. The stem cell and longitudinal sections were much more extensively affected in susceptible plants than in resistant plants after pathogen infection. However, slightly deformed mesophyll cells were observed in the leaves of susceptible plants. With transmission electron microscopy, we found that the cortical bundle cells and the cell contents and nuclei in the roots were more severely affected in the susceptible plants than in the resistant plants; in the stems and leaves, the nuclei, chloroplasts, and mesophyll cells changed significantly in the susceptible plants after fungal infection. Moreover, we found that infected susceptible and resistant plants were affected much more severely at the tillering stage (Z21) than at the seedling growth stage (Z13).ConclusionHistological changes in the wheat roots, stems and leaves were much more severe in T. controversa-infected susceptible plants than in infected resistant plants at the tillering stage (Z21).

Highlights

Dwarf bunt, which is caused by Tilletia controversa Kühn, is a soilborne and seedborne disease that occurs worldwide and can lead to 70% or even total losses of wheat crops
For the detection of T. controversa by confocal laser scanning microscopy, both in the stages of seedling growth (Z13) and tillering (Z21), we found the hyphae of T. controversa in both the infected resistant and susceptible wheat cultivars in the roots, stems, and leaves (Additional file 2)
Comparison of root, stem, and leaf tissue structures of resistant and susceptible plants with scanning electron microscopy Based on the resistant (Mianyang 26/Yumai 47) and susceptible cultivar (CU42), in the root cells, as shown in Fig. 1, there were few differences between the epidermal cells of the resistant cultivar and those in the mock treatment (Fig. 1a, b); in the inoculated susceptible cultivar, the epidermal cells were severely infected, and some damage appeared on the epidermal cells (Fig. 1d)

Summary

Introduction

Dwarf bunt, which is caused by Tilletia controversa Kühn, is a soilborne and seedborne disease that occurs worldwide and can lead to 70% or even total losses of wheat crops. Very little information is available about the histological changes that occur in dwarf bunt-resistant and dwarf bunt-susceptible wheat plants at the tillering stage (Z21). We used scanning electron microscopy and transmission electron microscopy to characterize the histological changes at this stage in resistant and susceptible wheat cultivars infected by T. controversa. Dwarf bunt of wheat is one of the most serious diseases of this crop in the world, and it is a quarantine disease in many countries [2,3,4]. T. controversa, a soilborne and seedborne fungal pathogen, is the causal agent of dwarf bunt of wheat. Losses due to dwarf bunt reach 10–20%, but under severe conditions, losses can reach 70–80% or even complete crop failure [7]

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