Bacterial diversity and communities in different parts of the medicinal plant Capparis spinosa L.

Abstract:

[Objective] To understand the bacterial community structures, species composition, and diversity in different parts of the medicinal plant Capparis spinosa L., so as to provide a theoretical basis for developing the microbial resources in medicinal plants and revealing the interactions between microorganisms and hosts. [Methods] The aboveground tissue (fruit and stem) samples of plants and soil (rhizosphere soil and bulk soil) samples were collected. High-throughput sequencing of bacterial 16S rRNA gene hypervariable regions V5-V7 and V3-V4 was employed to compare the bacterial community structure, species composition, and function in different samples. [Results] A total of 3 649 (operational taxonomic unit, OTUs) were annotated for the sequencing results of the four samples, belonging to 1 051 genera, 464 families, 248 orders, 88 classes of 34 phyla. The bacterial diversity in soil samples was higher than that in plant samples, following the trend of rhizosphere soil>bulk soil>stems>fruits. The bacterial diversity in fruits was always the lowest and significantly lower than that in rhizosphere soil. At the phylum level, Proteobacteria was dominant in plant samples, Proteobacteria and Actinobacteriota in rhizosphere soil, and Firmicutes and Actinobacteriota in bulk soil. At the genus level, Achromobacter, Erwinia, Enterococcus, Exiguobacterium, Lactobacillus, and Klebsiella were dominant in the plant samples, and Planomicrobium,Kocuria, Paenibacillus, Streptomyces, Microvirga, and Arthrobacter in the soil samples. The beta diversity analysis indicated that the bacterial community structure had significant differences between plant samples and soil samples and was similar in the same type of samples. [Conclusion] The bacterial diversity and abundance in soil samples were higher than those in plant samples, and the bacterial community structure varied between different parts of Capparis spinosa L. The findings provide accurate microbial information for exploring the function of and utilizing the bacteria in this medicinal plant.