A microecological research reveals seasonal variation in rhizosphere-endophytic bacteria and growth and development of Codonopsis pilosula root

Codonopsis pilosula is a medicinal and edible plant. Its chemical composition and pharmacological effects have been extensively studied. However, temporal, especially seasonal variabilities of bacterial composition driving nutrient cycling are poorly understood in rhizosphere and endosphere of C. pilosula. This study aimed to investigate the relationships and distinctions among soil physicochemical characteristics, microbial diversity, and functions of C. pilosula under different seasonal conditions in Longxi, China, and how these factors influenced C. pilosula growth. Physicochemical characteristics, enzymatic activities, growth state and metabolite analysis of C. pilosula in the soil were conducted using multispectral techniques. High-throughput sequencing methods were employed to analyze the alpha- and beta-diversity of rhizospheric and endophytic bacterial communities. Seasonal changes (P < 0.05) significantly influenced physiological indicators, bacterial diversity, community structure, and ecological niche breadth of C. pilosula, which were affected by environmental variables and soil enzymes. The neutral community model indicated that stochasticity played a substantial role in bacterial community development in rhizosphere soil. Furthermore, the microbial diversity was influenced by the soil's electrical conductivity, urease, and catalase activities, as well as phosphorus and potassium concentrations. Seasonal fluctuations significantly impacted the growth, development, metabolite content, and stress resistance indicators, such as antioxidant enzymes, in C. pilosula. By analyzing the temporal characteristics between plant and soil indicators, this study provides insights into regulating environmental factors during C. pilosula growth to enhance its yield and quality. Main conclusion Both rhizosphere soil physicochemical factors and bacterial diversity indices showed strong correlations. Phylogenetic and taxonomic differences existed between rhizosphere and bulk soil bacterial communities of Codonopsis pilosula in different seasons.