[In-situ analysis of metabolic changes in Scutellaria baicalensis root rot tissues base on MALDI mass spectrometry...

The medicinal part of Scutellaria baicalensis is its dried root, which has the effects of clearing heat, drying dampness, purging fire, removing toxin, stopping bleeding, and preventing miscarriage. Fusarium solani is one of the pathogenic microorganisms responsible for root rot of S. baicalensis, and this disease significantly reduces the quality of S. baicalensis. Few studies have analyzed the metabolic changes in S. baicalensis root rot tissues. The paper modeled root rot by inoculating healthy S. baicalensis root tissues with F. solani. Toluidine blue and wheat germ agglutinin(WGA) staining were used to observe the colonization characteristics of the pathogen. Matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI) was employed for imaging analysis of metabolites in tissue sections of S. baicalensis roots. Degradation of baicalin and wogonoside by F. solani was verified by biotransformation experiments. The results showed the colonization of a large number of fungi and the formation of dead tissue near the phloem of diseased S. baicalensis root tissue. MALDI-MSI showed that the content and spatial distributions of metabolites such as amino acids, organic acids, sugars, flavonoids, and phenolic acids were significantly different in the two kinds of tissues. Biotransformation experiments verified that F. solani was able to significantly degrade baicalin and wogonoside. In this study, the spatial distribution characteristics of metabolite changes in S. baicalensis root rot tissues were characterized for the first time, and the change pattern of the metabolites during pathogen infestation was revealed. This study provided a preliminary understanding of the pathological mechanism of root rot, which affects the quality of medicinal herbs, and provided a reference for the establishment of an early warning system based on metabolic markers to guide selection and breeding of disease-resistant varieties and quality control.