Factors stimulating germination of Plasmodiophora brassicae resting spores

by Yao Wang
Doctoral thesis
Date of Examination:2021-06-17
Date of issue:2022-12-07
Advisor:Prof. Dr. Andreas von Tiedemann
Referee:Prof. Dr. Jutta Ludwig-Müller
Referee:Prof. Dr. Klaus Dittert
Persistent Address: http://dx.doi.org/10.53846/goediss-9600

 

 

Files in this item

Name:Thesis_Yao_final.pdf
Size:3.46Mb
Format:PDF

The following license files are associated with this item:

Abstract

English

Cruciferous crops have significant economic value as vegetables, edible and industrial oil sources, animal feeds, manure and biofuel. Clubroot caused by Plasmodiophora brassicae, a worldwide spread soil-borne disease seriously restricts the production of cruciferous crops. The major symptom of clubroot is single or multiple root galls that limit the uptake of water and nutrients leading to stunting and considerable losses in yield and quality. The germination of P. brassicae resting spores is a key determinant of infection and disease severity. Thus, identifying biotic and abiotic stimulants for spore germination is imperative for developing novel clubroot control strategies. The accurate assessment of viability and germination rate is the foundation to evaluate the effect of control methods. In this study, we optimized several methods for the assessment of viability and germination rate of P. brassicae resting spores to obtain reliable estimates. Furthermore, our studies showed that pure root exudates collected under sterile conditions cannot trigger resting spore germination, which is contrasted to previous studies. Instead, various bioassays results demonstrated that soil bacteria are essential for P. brassicae resting spore germination. We found that certain carbon sources and nitrate can reshape the initial microbial community to an inducing community leading to the germination of P. brassicae resting spores. The stimulating communities significantly differed in composition and abundance of bacterial taxa compared to the non-stimulating ones. A multi-factorial ‘pathobiome’ model comprising abiotic and biotic factors is proposed to represent the putative plant-microbiome-pathogen interactions associated with breaking spore dormancy of P. brassicae in soil. This study presents novel insights significantly improving our understanding about the interaction of soil microbiota with P. brassicae and its host plant, which may develop novel strategies of clubroot disease control.
Keywords: Clubroot; Germination; CLSM; Disease severity; Microbial community; Root exudates; Pathobiome
 
Statistik