Analysis of endophytic and rhizosphere bacterial diversity and function in the endangered plant Paeonia ludlowii

Yazhou Lu,Hao Cai,Fang Yuan,Xiaozhong Lan,Xiu Yin,Erhao Zhang,Lianqiang Li,Mingsheng Hong,Kentian Zhao,Lei Yuan

doi:10.1007/s00203-020-01882-3

Abstract

Paeonia ludlowii is indigenous to Tibet and has an important ecological and economic value in China. In Tibet, P. ludlowii has been used in folk medicine with relative success. Plant microbial endophytes play an important role in plant growth, health and ecological function. The diversity of endophytic bacteria associated with P. ludlowii remains poorly understood. In this study, the structure of the endophytic bacterial communities associated with different tissues, including fruits, flowers, leaves, stems, and roots, and rhizosphere soils was analyzed with Illumina MiSeq sequencing of bacterial 16S rDNA. A total of 426,240 sequences and 4847 operational taxonomic units (OTUs) were obtained. The OTUs abundance of roots was higher than that of other tissues; however, the OTUs abundance was similar among different deep soil samples. In the plant tissues, Cyanobacteria was the most abundant bacterial phylum, followed by Proteobacteria; however, the most abundant phyla were Proteobacteria and Acidobacteria in soil samples from three different layers. In addition, the diversity and richness of the microorganisms in the soil were very similar to those in roots but higher than those in other tissues of P. ludlowii. Predictive metagenome analysis revealed that endophytic bacteria play critical functional roles in P. ludlowii. This conclusion could facilitate the study of the ecological functions of endophytic bacteria and their interactions with P. ludlowii to analyze the reasons why this important medicinal plant is becoming endangered.

Highlights

The Tibetan peony, Paeonia ludlowii, is an endemic species to the Himalayan-Hengduan Mountains; it is renowned as a medicinal plant that reduces inflammation (Liu et al 2017; Lou et al 2017) and is only distributed in a small area of southern Tibet in western China (Hao et al 2014)
The sequence analysis revealed that endophytic bacteria were clustered into 43 phyla; Cyanobacteria was the most dominant phylum, accounting for 70.3–88.0% of all bacterial sequences in the different tissues, followed by Proteobacteria
Cyanobacteria are the oldest photoautotrophs with nitrogen fixation capabilities and synthesize a large variety of metabolic compounds that exhibit biomaterial and biofertilizer production capabilities, including phycobiliproteins (PBPs), which may be an important target in biotechnology and biomedical research (Gonzalez et al 2019; Rastogi and Sinha 2009; Rastogi et al 2017)

Summary

Introduction

The Tibetan peony, Paeonia ludlowii, is an endemic species to the Himalayan-Hengduan Mountains; it is renowned as a medicinal plant that reduces inflammation (Liu et al 2017; Lou et al 2017) and is only distributed in a small area of southern Tibet in western China (Hao et al 2014). Endophyte studies might provide a way to improve seed germination. Endophytes are nonpathogenic microbes that reside in healthy plant tissues and benefit both the plants and the microbes. Bacterial endophytes play important roles in plant growth, health and ecological function, conferring certain benefits to plants (Lumactud and Fulthorpe 2018). A growing body of literature has reported that bacterial endophytes promote plant growth, improve plant health, enhance plant tolerance to stress and provide many additional benefits (Azevedo et al 2000; Hardoim et al 2008; Glick and Stearns, 2011; Mitter et al 2017). Understanding the community and diversity of endophytic bacteria in plant tissues is imperative

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