A Microbiome Study Reveals Seasonal Variation in Endophytic Bacteria Among different Mulberry Cultivars

Abstract

Knowledge of seasonal shifts in the bacterial community composition among different mulberry ( Morus L.) cultivars will facilitate to develop the biocontrol phytopathogens strategy using endophytic bacteria. The present study investigated the endophytic bacterial communities of four mulberry cultivars that have different resistance to mulberry fruit sclerotiniosis using Illumina-based sequencing of the 16S rRNA gene fragment in spring and autumn. The results indicated that spring samples harbor higher bacterial operational taxonomic units (OTUs), α-diversity, and bacterial community complexity in comparison with autumn samples. The taxonomic composition analysis showed that the majority of endophytes were composed of Proteobacteria (genus level: Methylobaterium ) and Actinobacteria in spring, while sequences classified as Proteobacteria (genus level: Pantoea and Pseudomonas ) were abundant in autumn. Analysis of β-diversity also revealed endophytic bacteria were divided into two main groups by season. By comparison among different mulberry cultivars, we found that Pantoea , Methylobaterium , and Pseudomonas were the three major bacterial genera in all cultivars, while their relative abundances varied with cultivars and appeared no obvious relationship with resistance level of mulberry fruit sclerotiniosis. The complex correlation of the endophytic communities in susceptible mulberry cultivars was higher than that of the resistant cultivars. Overall, the findings suggested that season plays a key role in determining the mulberry endophytic bacterial communities, followed by host cultivar, and Proteobacteria was the predominant phylum in both seasons and different mulberry cultivars.

White Mulberry (Morus Alba L.) Fruit-Associated Bacterial and Fungal Microbiota

“…Several aspects aggravate comparative analysis of our data with previous Morus L. microbiome studies: different plant site were chosen (in our study -fruits, in in mentioned above studies -stems), the lack of information on exact mulberry species of tested cultivars, and microorganisms analyzed (ours -epiphytic, in mentioned above studies -endophytic bacteria). Nevertheless, analysis of taxonomic composition of prokaryotic microorganisms revealed that Actinobacteria, Firmicutes, and Proteobacteria were the three most abundant bacterial phyla on different Morus L. cultivars, mainly represented by Pantoea, Pseudomonas, and Methylobacterium genera (Ou et al, 2019;Xu et al, 2019). In our study, about 90% of M. alba fruits were also covered by microorganisms belonging to these phyla but represented by different genera.…”

“…So far, a few studies were focused on the characterization of bacterial community distributed on different Morus L. cultivars using culture-dependent (Xu et al, 2019) and metagenomics (Ou et al, 2019) approaches. It was demonstrated that the endophytic Morus L. microorganism assemblies are specific for the host plant and the climatic conditions (Ou et al, 2019).…”

“…So far, a few studies were focused on the characterization of bacterial community distributed on different Morus L. cultivars using culture-dependent (Xu et al, 2019) and metagenomics (Ou et al, 2019) approaches. It was demonstrated that the endophytic Morus L. microorganism assemblies are specific for the host plant and the climatic conditions (Ou et al, 2019). Several aspects aggravate comparative analysis of our data with previous Morus L. microbiome studies: different plant site were chosen (in our study -fruits, in in mentioned above studies -stems), the lack of information on exact mulberry species of tested cultivars, and microorganisms analyzed (ours -epiphytic, in mentioned above studies -endophytic bacteria).…”

“…Mulberry trees (Morus L.) have been widely cultivated in temperate and subtropical regions of Africa, America, Asia and Europe; their planting steadily increases every year due to realized economic and ecological benefits (Ou et al, 2019;Xu et al, 2019). Mulberry (Morus spp.)…”

“…It must be mentioned that very few works concentrated on the characterization of mulberryassociated microbial assemblages are published so far. Some studies are focused on the diversity of endophytic bacteria on white mulberry cultivars by revealing seasonal variation and emphasizing antimicrobial and plant growth-promoting activities of bacteria (Ou et al, 2019;Xu et al, 2019). Only two studies are intended for characterization of soil fungal communities of different white mulberry genotypes and analysis of relationship with fruit sclerotiniosis (Zhang et al, 2019;Yu et al, 2016).…”