The Bacterial and Fungal Compositions in the Rhizosphere of Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. in a Typical Planting Region

Abstract

Asarum is a traditional Chinese medicinal plant, and its dried roots are commonly used as medicinal materials. Research into the traits of the bacteria and fungus in the Asarum rhizosphere and how they relate to the potency of medicinal plants is important. During four cropping years and collecting months, we used ITS rRNA gene amplicon and sequencing to assess the population, diversity, and predominant kinds of bacteria and fungus in the rhizosphere of Asarum. HPLC was used to determine the three bioactive ingredients, namely asarinin, aristolochic acid I, and volatile oil. The mainly secondary metabolites of Asarum, relationships between microbial communities, soil physicochemical parameters, and possible influences on microbial communities owing to various cropping years and collecting months were all statistically examined. The cropping years and collecting months affected the abundance and diversity of rhizosphere bacteria and fungi, but the cropping year had a significant impact on the structures and compositions of the bacterial communities. The rhizosphere microorganisms were influenced by both the soil physicochemical properties and enzyme activities. Additionally, this study revealed that Trichoderma was positively correlated with the three bioactive ingredients of Asarum, while Tausonia showed entirely opposite results. Gibberella and Leptosphaeria demonstrated a significantly negative correlation with asarinin and violate oil, but they were weakly correlated with the aristolochic acid I content. This study revealed variations in the Asarum rhizosphere microorganism population, diversity, and dominant types across four cropping years and collecting months. The relationship between Asarum secondary metabolites, the soil physicochemical properties, enzyme activities, and rhizosphere microorganisms was discussed. Our results will guide the exploration of the soil characteristics and rhizosphere microorganisms’ structures by regulating the microbial community to enhance Asarum quality.