Transcriptomics and metabolomics revealed the synthesis and potential role of flavonoids in pea roots under continuous cropping obstacles

Abstract With the continuation of intensive and monoculture production in modern agriculture, the harm of continuous cropping obstacles is becoming more prominent. Pea has important nutritional and economic value, but it is easy to have continuous cropping obstacles in production. However, there is limited knowledge of the regulatory mechanisms of pea to cope with continuous cropping obstacles. In this study, we found that the number of differential expressed genes (DEGs) and differential metabolites (DAMs) increased in the pea roots with increasing continuous cropping times, and the number of DEGs and DAMs in roots of sensitive pea was more than that of continuous cropping tolerant pea. Comprehensive analysis of the omics data revealed that the flavonoid and isoflavonoid biosynthesis pathways play key roles in the response of pea roots to the continuous cropping obstacles. Most of the DEGs involved in these two pathways were up‐regulated. Meanwhile, most of the flavonoid compounds and total flavonoid content increased. With increasing continuous cropping times, the isoflavones category in DAMs increased, and the isoflavones category in the roots of continuous cropping tolerant pea were higher than in sensitive pea. Additionally, the isoflavonoid (biochanin A, calycosin, genistein) in the roots of continuous cropping tolerant pea have the ability to inhibit the growth of fungi in pea soil and possess antioxidant activity. These findings revealed the important role of flavonoids in pea continuous cropping obstacles and laid a foundation for effectively alleviating pea continuous cropping obstacles in the future.