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The intricate interplay between endophytic microorganisms and plants in the upkeep of biodiversity, the stability of communities, and the operation of ecosystems needs to be more adequately extensive. Although root-associated microbial communities of plants have been revealed for the last decade, the understanding of bacterial and fungal communities associated with the roots of medicinal plants remains elusive. To highlight the importance of Panax ginseng Meyer (PG) in our research, we investigated the root endophytic bacterial and fungal communities of Panax ginseng Meyer (PG), alongside Aralia cordata (AC), Angelica gigas (AG), and Peucedanum japonicum (PJ), utilizing amplicon-based community profiling and advanced bioinformatic methodologies. The study aimed to investigate the root-endophytic microbiota of ginseng and three other medicinal plants and identify similarities in microbiome composition across different plant species and families. Results revealed that root-endophytic bacterial and fungal communities were influenced by plant species and phylogenetic differences at the family level. Differential abundance tests and random forest models showed microbial features within the same plant family. PG had a distinctive microbial profile with significant B1653_o_Enterobacterales and F8_o_Helotiales. PG had a core microbiome, B10_Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, and a more evenly distributed microbial network compared to AG, PJ, and AC. Our research reveals the intricate endophytic microbial communities within the roots of medicinal plants, pinpointing specific taxa that may be pivotal to their medicinal qualities and overall plant health. These insights carry notable implications for future studies, particularly those focused on the endophytes of PG and their secondary metabolites, as they deepen our understanding of plant-microbe interactions and their role in enhancing the plants' therapeutic potential., Competing Interests: Declarations. Competing interests: The authors declare no competing interests. Ethical approval: The research conducted adhered to the guidelines outlined in the IUCN Policy Statement on Research Involving Species at Risk of Extinction and Convention on the Trade in Endangered Species of Wild Fauna and Flora., (© 2024. The Author(s).)

A novel actinomycete strain, designated RP-AC37(T), was isolated from rhizosphere soil collected on Mara Island of Jeju, Republic of Korea. Cells were aerobic, gram-positive, oxidase-negative, catalase-positive, non-mycelium-forming and motile rods (0.6-0.7×1.9-2.4 µm). Phylogenetic analysis based on 16S rRNA gene sequences showed that the organism formed a distinct clade within the radiation occupied by the suborder Frankineae. 16S rRNA gene similarity values were less than 93.2 % to members of the suborder Frankineae and related taxa. The diamino acid isomer in the cell-wall peptidoglycan was LL-diaminopimelic acid. The major whole-cell sugars were glucose, galactose and xylose. The major menaquinone was MK-9(H(4)). The polar lipids were diphosphatidylglycerol, phosphatidylcholine and phosphatidylinositol. The cellular fatty acids were straight-chain, unsaturated and saturated, with a significant amount of tuberculostearic acid (10-methyl-C(18 : 0)). The DNA G+C content was 73.2 mol%. The combination of morphological, chemotaxonomic and phylogenetic data clearly separate the isolate from members of known genera of the suborder Frankineae and related taxa, suggesting that the isolate represents a novel species in a new genus in this suborder, for which the name Motilibacter peucedani gen. nov., sp. nov. is proposed; the type strain is RP-AC37(T) ( = KCTC 19630(T) = DSM 45328(T)).

A novel actinomycete, designated strain RP-AC36(T), was isolated from a cliff-associated plant (Peucedanum japonicum Thunb.) in the Republic of Korea and its taxonomic status was determined by using a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequence analysis showed that the organism formed a distinct clade within the radiation of the genus Amycolatopsis. The chemotaxonomic properties supported the assignment of the isolate to the genus Amycolatopsis. High levels of 16S rRNA gene sequence similarity were found with Amycolatopsis sulphurea (98.2 %), Amycolatopsis halotolerans (97.5 %) and Amycolatopsis jejuensis (97.1 %). DNA-DNA relatedness data, together with phenotypic differences, clearly distinguished the isolate from its closest relative A. sulphurea. Based on the phenotypic and genotypic evidence, it is suggested that the organism be assigned as representing a novel species of the genus Amycolatopsis, for which the name Amycolatopsis ultiminotia sp. nov. is proposed. The type strain is RP-AC36(T) (=NRRL B-24662(T)=DSM 45180(T)).

An increasingly popular approach used to identify arbuscular mycorrhizal (AM) fungi in planta is to amplify a portion of AM fungal small subunit ribosomal DNA (SSU-rDNA) from whole root DNA extractions using the primer pair AM1-NS31, followed by cloning and sequencing. We used this approach to study the AM fungal community composition of three common oak-woodland plant species: a grass (Cynosurus echinatus), blue oak (Quercus douglasii), and a forb (Torilis arvensis). Significant diversity of AM fungi were found in the roots of C. echinatus, which is consistent with previous studies demonstrating a high degree of AM fungal diversity from the roots of various hosts. In contrast, clones from Q. douglasii and T. arvensis were primarily from non-AM fungi of diverse origins within the Ascomycota and Basidiomycota. This work demonstrates that caution must be taken when using this molecular approach to determine in planta AM fungal diversity if non-sequence based methods such as terminal restriction fragment length polymorphisms, denaturing gradient gel electrophoresis, or temperature gradient gel electrophoresis are used.