Taxonomical and functional composition of strawberry microbiome is genotype-dependent.

INTRODUCTION: Specific microbial communities are associated to host plants, influencing their phenotype and fitness.Despite the rising interest in plant microbiome, the role of microbial communities associated with perennial fruit plants remains overlooked. OBJECTIVES: This work provides the first comprehensive descriptionof the taxonomical and functional bacterial and fungal microbiota of below- and above-ground organsof three commercially important strawberry genotypes under cultural conditions. METHODS: Strawberry-associatedfungal and bacterial microbiomes were characterised by Next-Generation Sequencing and the potential functions expressed by the bacterial microbiome were analysed by both in silico and in vitro characterisation of plant growth-promoting abilities of native bacteria. Additionally, the association between the strawberry microbiome, plant disease tolerance, plant mineral nutrient content, and fruit quality was investigated. RESULTS: Results showed that thestrawberry core microbiome included 24 bacteria and 15 fungal operational taxonomicunits (OTUs).However, plant organ and genotype had a significant role in determining the taxonomical and functional composition of microbial communities. Interestingly, the cultivar with the highesttolerance against powdery mildew and leaf spot and the highest fruit productivity was the only one able to ubiquitously recruit the beneficial bacterium, Pseudomonasfluorescens, and to establish a mutualistic symbiosis with the arbuscular mycorrhizaRhizophagus irregularis. CONCLUSION: This work sheds light on the interaction of cultivated strawberry genotypes with a variety of microbes and highlights the importance of their applications to increase the sustainability of fruit crop production.

Identifying Hidden Viable Bacterial Taxa in Tropical Forest Soils Using Amplicon Sequencing of Enrichment Cultures.

This study aims to estimate the proportion and diversity of soil bacteria derived from eDNA-based and culture-based methods. Specifically, we used Illumina Miseq to sequence and characterize the bacterial communities from (i) DNA extracted directly from forest soil and (ii) DNA extracted from a mixture of bacterial colonies obtained by enrichment cultures on agar plates of the same forest soil samples. The amplicon sequencing of enrichment cultures allowed us to rapidly screen a culturable community in an environmental sample. In comparison with an eDNA community (based on a 97% sequence similarity threshold), the fact that enrichment cultures could capture both rare and abundant bacterial taxa in forest soil samples was demonstrated. Enrichment culture and eDNA communities shared 2% of OTUs detected in total community, whereas 88% of enrichment cultures community (15% of total community) could not be detected by eDNA. The enrichment culture-based methods observed 17% of the bacteria in total community. FAPROTAX functional prediction showed that the rare and unique taxa, which were detected with the enrichment cultures, have potential to perform important functions in soil systems. We suggest that enrichment culture-based amplicon sequencing could be a beneficial approach to evaluate a cultured bacterial community. Combining this approach together with the eDNA method could provide more comprehensive information of a bacterial community. We expected that more unique cultured taxa could be detected if further studies used both selective and non-selective culture media to enrich bacteria at the first step.

Future Climate Significantly Alters Fungal Plant Pathogen Dynamics during the Early Phase of Wheat Litter Decomposition.

Returning wheat residues to the soil is a common practice in modern agricultural systems and is considered to be a sustainable practice. However, the negative contribution of these residues in the form of "residue-borne pathogens" is recognized. Here, we aimed to investigate the structure and ecological functions of fungal communities colonizing wheat residues during the early phase of decomposition in a conventional farming system. The experiment was conducted under both ambient conditions and a future climate scenario expected in 50-70 years from now. Using MiSeq Illumina sequencing of the fungal internal transcribed spacer 2 (ITS2), we found that plant pathogenic fungi dominated (~87% of the total sequences) within the wheat residue mycobiome. Destructive wheat fungal pathogens such as Fusarium graminearum, Fusarium tricinctum, and Zymoseptoria tritci were detected under ambient and future climates. Moreover, future climate enhanced the appearance of new plant pathogenic fungi in the plant residues. Our results based on the bromodeoxyuridine (BrdU) immunocapture technique demonstrated that almost all detected pathogens are active at the early stage of decomposition under both climate scenarios. In addition, future climate significantly changed both the richness patterns and the community dynamics of the total, plant pathogenic and saprotrophic fungi in wheat residues as compared with the current ambient climate. We conclude that the return of wheat residues can increase the pathogen load, and therefore have negative consequences for wheat production in the future.