1H NMR-Based Metabolomics to Identify Resistance-Related Metabolites in Astragalus membranaceus var. mongholicus against Fusarium Root Rot

Root rot is a destructive disease of Astragalus membranaceus var. mongholicus (AMM) and occurs frequently in recent years in the main cultivation regions in China. However, the progress of AMM resistance breeding is extremely slow due to the lack of resistance source and inefficiency of the conventional disease resistance evaluation method. This study aimed to provide information on the interaction between AMM and Fusarium solani, one of the predominant pathogens causing root rot and identify the resistance-related (RR) metabolites by using the nontargeted 1H nuclear magnetic resonance (NMR) metabolomics approach. Of the 24 metabolites examined, the concentration changes in sucrose, fructose, taurine and phenylalanine were negatively correlated with the root rot severity. The abundance of malic acid in F. solani-inoculated samples considerably decreased at 21 days post inoculation (dpi). The five metabolites were identified as RR metabolites, and only malic acid inhibited the fungal growth. These metabolites might serve as candidate biomarkers for discriminating the resistance levels of different AMM genotypes and establishing the high-throughput screening method of AMM breeding lines against root rot caused by F. solani. Results could assist in accelerating the resistance breeding program. The possible mechanisms of RR metabolites in plant defense against the pathogen were discussed. © 2021 Friends Science Publishers