Comparative Metagenomic Analysis Reveals Rhizosphere Microbiome Assembly and Functional Adaptation Changes Caused by Clubroot Disease in Chinese Cabbage.

Clubroot is a major disease and severe threat to Chinese cabbage, and it is caused by the pathogen Plasmodiophora brassicae Woron. This pathogen is an obligate biotrophic protist and can persist in soil in the form of resting spores for more than 18 years, which can easily be transmitted through a number of agents, resulting in significant economic losses to global Chinese cabbage production. Rhizosphere microbiomes play fundamental roles in the occurrence and development of plant diseases. The changes in the rhizosphere microorganisms could reveal the severity of plant diseases and provide the basis for their control. Here, we studied the rhizosphere microbiota after clubroot disease infections with different severities by employing metagenomic sequencing, with the aim of exploring the relationships between plant health, rhizosphere microbial communities, and soil environments; then, we identified potential biomarker microbes of clubroot disease. The results showed that clubroot disease severity significantly affected the microbial community composition and structure of the rhizosphere soil, and microbial functions were also dramatically influenced by it. Four different microbes that had great potential in the biocontrol of clubroot disease were identified from the obtained results; they were the genera Pseudomonas, Gemmatimonas, Sphingomonas, and Nocardioides. Soil pH, organic matter contents, total nitrogen, and cation exchange capacity were the major environmental factors modulating plant microbiome assembly. In addition, microbial environmental information processing was extremely strengthened when the plant was subjected to pathogen invasion, but weakened when the disease became serious. In particular, oxidative phosphorylation and glycerol-1-phosphatase might have critical functions in enhancing Chinese cabbage's resistance to clubroot disease. This work revealed the interactions and potential mechanisms among Chinese cabbage, soil environmental factors, clubroot disease, and microbial community structure and functions, which may provide a novel foundation for further studies using microbiological or metabolic methods to develop disease-resistant cultivation technologies.

Profiles of phenolics and their synthetic pathways in Asparagus officinalis L.

The synthetic pathways of some phenolics compounds in asparagus have been reported, however, the diversified phenolics compounds including their modification and transcription regulation remains unknown. Thus, multi-omics strategies were applied to detect the phenolics profiles, contents, and screen the key genes for phenolics biosynthesis and regulation in asparagus. A total of 437 compounds, among which 204 phenolics including 105 flavonoids and 82 phenolic acids were detected with fluctuated concentrations in roots (Rs), spears (Ss) and flowering twigs (Fs) of the both green and purple cultivars. Based on the detected phenolics profiles and contents correlated to the gene expressions of screened synthetic enzymes and regulatory TFs, a full phenolics synthetic pathway of asparagus was proposed for the first time, essential for future breeding of asparagus and scaled healthy phenolics production using synthetic biological strategies.