Soil nutrients, rhizosphere bacteria, and endophytes interact to influence the accumulation of amino acid-short peptide components in Angelica sinensis roots, each playing distinct roles

Abstract

Improving the medicinal quality of Angelica sinensis root (Ang) through microecological regulation is crucial; however, the factors shaping the active ingredients require further exploration. This study simultaneously examined the soil physicochemical properties, the rhizosphere-endophytic bacterial communities, and the metabolic components of Ang from various authentic planting sites, followed by an association analysis. Three representative sites were highlighted: Site #1 had the lowest soil nitrogen-phosphorus-potassium contents, while Site #2 exhibited the highest levels; Site #3 was moderate but demonstrated dominant organic carbon due to high soil sucrase activity. Corresponding to the soil conditions, the abundance of rhizosphere-endophytic beneficial bacteria at Site #1 was the lowest. In contrast, Sites #2 and #3 showed dominance in rhizosphere bacteria and endophytes, respectively. Regarding active ingredients, Ang from Site #1 primarily accumulated host defense-related amino acids and derivatives. The abundance of short peptides was highest in Ang from Site #2, whereas Site #3 had the highest relative content of total amino acids, short peptides, and derivatives (AASPD). Mathematical fitting indicated that under the synergism of soil conditions, rhizosphere bacteria (such as Flavobacterium, Stenotrophomonas, and Paracoccus) had the most significant effect on overall AASPD (path coefficient = 0.806, p = 0.0006). In contrast, endophytic bacteria (such as Parasutterella, Parabacteroides, and Bacteroides) specifically influenced short peptides, with path coefficients and p-value of 1.035 and 0.0006, respectively. Overall, key microecological factors interact with one another, shaping the AASPD components in Ang with varying effects. These findings can provide references for enhancing the quality of Ang through microecological regulation.