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Juvenile individual of Dioon edule from the botanical garden. The radicular system of the Dioon species consist of a primary root, secondary root, precoralloid root and coralloid root. Also shown is a cross-section of the coralloid root without magnification, highlighting the 'algal or cyanobacterial zone'.
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Cycads are among the few plants that have developed specialized roots to host nitrogen-fixing bacteria. We describe the bacterial diversity of the coralloid roots from seven Dioon species and their surrounding rhizosphere and soil. Using 16S rRNA gene amplicon sequencing, we found that all coralloid roots are inhabited by a broad diversity of bacte...
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... roots samples of both juvenile (Fig 1) and adult plants (S1 Fig) were collected in April 2016 from the Botanical Garden "Francisco Javier Clavijero" from the Instituto Nacional de Ecología, A.C. in Xalapa (INECOL), Veracruz, Mexico (n = 13); and from a natural population (n = 4) from Santiago Lachiguiri, Oaxaca, Mexico. The samples collection in the described field study was authorized by the curator of the botanical garden Andrew P. Vovides and for the natural population by the Secretary of the Environment and Natural Resources (SEMARNAT) with the official permit number SGPA/DGVS/00064/16. ...
Citations
... Cycads have evolved specialized symbiotic associations with microbes, making them essential to understanding the origin and maintenance of plant-microbe interactions and their role in shaping the secondary chemistry across the evolution of land plants (Zheng & Gong 2019;Whitaker & Salzman 2020). Notably, nitrogen-fixing cyanobacteria are the dominant functional group within the coralloid roots of all cycads (Gehringer et al. 2010;Yamada et al. 2012;Gutiérrez-García et al. 2018;Zheng et al. 2018;Suárez-Moo et al. 2019;). Yet to our knowledge, no studies have addressed the leaf microbiota of cycads, thereby limiting our understanding of the interactions between endophytes and their host plants. ...
... The coevolution of cycads and associated microbes has yielded a highly specialized biotic association within their plant tissues (Suárez-Moo et al. 2019;Zheng & Gong 2019). Yet, connecting specific plant-microbe interactions to the highly toxic and diverse defensive metabolites observed in cycads has been significantly challenging due to the difficulties of integrating different data types (Cox et al. 2003;Marler et al. 2010;Mantas et al. 2022). ...
Plant–microbe interactions play a pivotal role in shaping host fitness, especially concerning chemical defense mechanisms. In cycads, establishing direct correlations between specific endophytic microbes and the synthesis of highly toxic defensive phytochemicals has been challenging. Our research delves into the intricate relationship between plant–microbe associations and the variation of secondary metabolite production in two closely related Zamia species that grow in distinct habitats; terrestrial and epiphytic. Employing an integrated approach, we combined microbial metabarcoding, which characterize the leaf endophytic bacterial and fungal communities, with untargeted metabolomics to test if the relative abundances of specific microbial taxa in these two Zamia species were associated with different metabolome profiles. The two species studied shared approximately 90% of the metabolites spanning diverse biosynthetic pathways: alkaloids, amino acids, carbohydrates, fatty acids, polyketides, shikimates, phenylpropanoids, and terpenoids. Co-occurrence networks revealed positive associations among metabolites from different pathways, underscoring the complexity of their interactions. Our integrated analysis demonstrated to some degree that the intraspecific variation in metabolome profiles of the two host species was associated with the abundance of bacterial orders Acidobacteriales and Frankiales, as well as the fungal endophytes belonging to the orders Chaetothyriales, Glomerellales, Heliotiales, Hypocreales, and Sordariales. We further associate individual metabolic similarity with four specific fungal endophyte members of the core microbiota, but no specific bacterial taxa associations were identified. This study represents a pioneering investigation to characterize leaf endophytes and their association with metabolomes in tropical gymnosperms, laying the groundwork for deeper inquiries into this complex domain.
... These cyanobionts are facultative, recruited from the soil OPEN ACCESS for a transient symbiosis. Recently, it has become apparent that coralloid roots also contain other sympatric bacteria, such as Hypomicrobiales and Caulobacterales [5][6][7][8]. Biological nitrogen fixation (BNF) is believed to be the main function of the coralloid root microbiome, in exchange for carbon sources from the host [9,10]. Indeed, in nitrogen-poor environments, cycad leaves carry the same nitrogen fractionation signal as their diazotrophic cyanobionts, confirming the plant's reliance on symbiotic BNF [11]. ...
... Just as the putative shared symbiotic genes remain to be identified, it is also unknown if the non-cyanobacterial sympatric bacterial communities of the coralloid root have a role in the symbiotic behaviour of cyanobionts. These communities have been independently identified in lichens, bryophytes and Azolla [35][36][37][38], in addition to coralloid roots [5][6][7][8]. However, even when these microbiomes seem similar, no formal meta-analysis of these datasets has been done, which would be an important first step to test their overall roles during symbiosis, including symbiotic plasticity. ...
... The identified bacterial orders herein have been previously found in symbiotic communities from cycads [5][6][7][8]. Furthermore, seven bacterial orders, namely Nostocales, Hypomicrobiales, Caulobacterales, Sphingomonadales, Burkholderiales, Xanthomonadales and Sphingobacterales, have been also reported in symbiotic communities from bryophytes [21], lichens [35,38] and various Azolla species [37] (Fig. 2b). ...
Cycads are known to host symbiotic cyanobacteria, including Nostocales species, as well as other sympatric bacterial taxa within their specialized coralloid roots. Yet, it is unknown if these bacteria share a phylogenetic origin and/or common genomic functions that allow them to engage in facultative symbiosis with cycad roots. To address this, we obtained metagenomic sequences from 39 coralloid roots sampled from diverse cycad species and origins in Australia and Mexico. Culture-independent shotgun metagenomic sequencing was used to validate sub-community co-cultures as an efficient approach for functional and taxonomic analysis. Our metanalysis shows a host-independent microbiome core consisting of seven bacterial orders with high species diversity within the identified taxa. Moreover, we recovered 43 cyanobacterial metagenome-assembled genomes, and in addition to Nostoc spp., symbiotic cyanobacteria of the genus Aulosira were identified for the first time. Using this robust dataset, we used phylometagenomic analysis to reveal three monophyletic cyanobiont clades, two host-generalist and one cycad-specific that includes Aulosira spp. Although the symbiotic clades have independently arisen, they are enriched in certain functional genes, such as those related to secondary metabolism. Furthermore, the taxonomic composition of associated sympatric bacterial taxa remained constant. Our research quadruples the number of cycad cyanobiont genomes and provides a robust framework to decipher cyanobacterial symbioses, with the potential of improving our understanding of symbiotic communities. This study lays a solid foundation to harness cyanobionts for agriculture and bioprospection, and assist in conservation of critically endangered cycads.
... Using Sanger sequencing, most of the bacteria inside the roots had been identified as members of the order Nostocales, with mainly a single strain per coralloid root (Costa et al. 1999(Costa et al. , 2004Lindblad 2009). In the last decade, the use of DNA-based amplicon sequencing (16S rRNA) on next generation sequencing tools has revealed a large consortium of bacteria from different phyla within the coralloid roots of several species of the family Zamiaceae Gutiérrez-García et al. 2019;Suarez-Moo et al. 2019). ...
... The Zamiaceae is the predominant cycad family in the Neotropics ( Fig. 1) (Calonje et al. 2019). The coralloid roots of species of Zamiaceae (genera Dioon and Zamia) have Nostocaceae as one of the most common bacterial families, including the genera Nostoc and Calothrix (Gutiérrez-García et al. 2019;Suarez-Moo et al. 2019). The only three root Pr Cz microbiome studies available for species of Zamiaceae suggest a geographical pattern, in which, related cyanobacterial strains are found within the coralloid roots of geographically neighboring species Gutiérrez-García et al. 2019;Suarez-Moo et al. 2019). ...
... The coralloid roots of species of Zamiaceae (genera Dioon and Zamia) have Nostocaceae as one of the most common bacterial families, including the genera Nostoc and Calothrix (Gutiérrez-García et al. 2019;Suarez-Moo et al. 2019). The only three root Pr Cz microbiome studies available for species of Zamiaceae suggest a geographical pattern, in which, related cyanobacterial strains are found within the coralloid roots of geographically neighboring species Gutiérrez-García et al. 2019;Suarez-Moo et al. 2019). Cycads root endophytes are recruited from the plant, the substrate (e.g., soil), and the rhizosphere by horizontal transmission (Cuddy et al. 2012;Santoyo et al. 2016;Suarez-Moo et al. 2019). ...
Cycads are the only gymnosperms forming a symbiosis with nitrogen-fixing cyanobacteria in a specialized organ: the coralloid root. This paper investigates the endophytic bacterial community inhabiting the coralloid roots of two cycads from Panama. We sampled coralloid roots from Zamia nana (terrestrial) and Zamia pseudoparasitica (epiphytic). Then, we used the 16S rRNA amplicon marker to describe the entire bacterial community. We also designed a new marker to amplify the rbcL-rbcX spacer and around 100 bp of the rbcX gene, targeting cyanobacteria. We found that using 16S, endophytic bacteria diversity is represented mainly by the phyla Actinobacteria, Cyanobacteria, and Proteobacteria. In addition, 16S analyses showed that Zamia species do not share a core cyanobacterial community (using stringent 75% and 90% thresholds), while the two species shared 4 ASVs at a 50% threshold. The newly developed rbcL-rbcX marker revealed that both species share a core cyanobacterial community represented by a single amplicon sequence variant (ASV1) (Nostoc sp.) at 90% threshold that is found in the same phylogenetic clade of that contain mostly Panamanian symbiotic cyanobacteria. Using a 75% threshold, only three ASVs (ASV1, ASV2, ASV3) were present across samples, and five ASVs at 50% threshold. This new marker can effectively identify cyanobacteria ASVs and provide a better resolution for microbial analyses in autotroph cyanobacterial symbioses.
... Cycads have been extensively reported to associate with cyanobacteria such as Nostoc, Scytonema, and Richelia species, which fix atmospheric N for plant uptake [59,60]. Other studies have reported the presence of non-cyanobacterial species belonging to the Rhizobium, Mesorhizobium, Bradyrhizobium, and Burkholderia genera [20,25]. Though cyanobacterial species were not isolated from the coralloid roots, the presence of non-cyanobacterial species may have contributed to the reliance of E. villosus on NDFA. ...
... Though cyanobacterial species were not isolated from the coralloid roots, the presence of non-cyanobacterial species may have contributed to the reliance of E. villosus on NDFA. Nitrogen fixing bacteria belonging to the Lysinibacillus, Paenibacillus, Stenotrophomonas, Rhizobium, and Enterobacter genera isolated from the coralloid roots, have been reported to be associated with cycad species Dioon edule [25] and E. natalensis [11]. Ref. [20] reported that cycads are predominantly associated with rhizobial species however, in this study, E. villosus was associated with rhizobial and non-rhizobial bacteria. ...
Information on how bacteria in plants and soil, along with extracellular enzymes, affect nutrient cycling in Encephalartos villosus growing in phosphorus deficient and acidic scarp forests is lacking. Bacteria in coralloid roots, rhizosphere, and non-rhizosphere soils were isolated to de-termine the potential role of soil bacterial communities and their associated enzyme activities in nutrient contributions in rhizosphere and non-rhizosphere soils. The role of soil characteristics and associated bacteria on E. villosus nutrition and nitrogen source reliance was investigated. Encephalartos villosus leaves, coralloid roots, rhizosphere, and non-rhizosphere soils were col-lected at two scarp forests. Leaf nutrition, nitrogen source reliance, soil nutrition and extracellu-lar enzyme activities were assayed. A phylogenetic approach was used to determine the evolu-tionary relationship between identified bacterial nucleotide sequences. The clustering pattern of isolated bacterial strains was primarily dictated by the ecological niches from which they origi-nated (rhizosphere soil, non-rhizosphere soil, and coralloid roots), thus indicating that host-microbe interactions may be a key driver of this pattern, in line with the hologenome theory. There were insignificant differences in the phosphorus and nitrogen cycling enzyme activities in E. villosus rhizosphere and non-rhizosphere soils in both localities. Significantly positive correla-tions were recorded between nitrogen and phosphorus cycling enzymes and phosphorus and ni-trogen concentrations in rhizosphere and non-rhizosphere soils. Additionally, more than 70% of the leaf nitrogen was derived from the atmosphere. This study challenged the conventional ex-pectation that environmental filters alone dictate microbial community composition in similar habitats and revealed that host-microbe interactions, as proposed by the hologenome theory, are significant drivers of microbial community structuring. The isolated bacteria and their plant growth promoting traits play a role in E. villosus nutrition and nitrogen source reliance and se-crete nutrient cycling enzymes that promote nutrient availability in rhizosphere and non-rhizosphere soils.
... Most previous studies regarding endophytic cyanobacteria in the coralloid roots of cycads were devoted to the discovery of species diversity. Known cyanobacteria that have been identified in cycads include Nostoc [23][24][25][26][27][28][29][30], Anabaena [26,27], Calothrix [23,25,27,29], Desmonostoc [30], Microcoleus, Leptolyngbya, Chroococcus, Scytonema, Acaryochloris [29], Cylindrospermopsis, Trichormus [27], and Dolichospermum [28]. With the development of technology in high-throughput sequencing in recent years, increasing studies on cycad endophytes are shifting to the variation in endophytes in different species, plant tissues, and habitats. ...
... Most previous studies regarding endophytic cyanobacteria in the coralloid roots of cycads were devoted to the discovery of species diversity. Known cyanobacteria that have been identified in cycads include Nostoc [23][24][25][26][27][28][29][30], Anabaena [26,27], Calothrix [23,25,27,29], Desmonostoc [30], Microcoleus, Leptolyngbya, Chroococcus, Scytonema, Acaryochloris [29], Cylindrospermopsis, Trichormus [27], and Dolichospermum [28]. With the development of technology in high-throughput sequencing in recent years, increasing studies on cycad endophytes are shifting to the variation in endophytes in different species, plant tissues, and habitats. ...
... Most previous studies regarding endophytic cyanobacteria in the coralloid roots of cycads were devoted to the discovery of species diversity. Known cyanobacteria that have been identified in cycads include Nostoc [23][24][25][26][27][28][29][30], Anabaena [26,27], Calothrix [23,25,27,29], Desmonostoc [30], Microcoleus, Leptolyngbya, Chroococcus, Scytonema, Acaryochloris [29], Cylindrospermopsis, Trichormus [27], and Dolichospermum [28]. With the development of technology in high-throughput sequencing in recent years, increasing studies on cycad endophytes are shifting to the variation in endophytes in different species, plant tissues, and habitats. ...
As a gymnosperm group, cycads are known for their ancient origin and specialized coralloid root, which can be used as an ideal system to explore the interaction between host and associated microorganisms. Previous studies have revealed that some nitrogen-fixing cyanobacteria contribute greatly to the composition of the endophytic microorganisms in cycad coralloid roots. However, the roles of host and environment in shaping the composition of endophytic bacteria during the recruitment process remain unclear. Here, we determined the diversity, composition, and function prediction of endophytic bacteria from the coralloid roots of a widely cultivated cycad, Cycas revoluta Thunb. Using next-generation sequencing techniques, we comprehensively investigated the diversity and community structure of the bacteria in coralloid roots and bulk soils sampled from 11 sites in China, aiming to explore the variations in core endophytic bacteria and to predict their potential functions. We found a higher microbe diversity in bulk soils than in coralloid roots. Meanwhile, there was no significant difference in the diversity and composition of endophytic bacteria across different localities, and the same result was found after removing cyanobacteria. Desmonostoc was the most dominant in coralloid roots, followed by Nostoc, yet these two cyanobacteria were not shared by all samples. Rhodococcus, Edaphobacter, Niastella, Nordella, SH-PL14, and Virgisporangium were defined as the core microorganisms in coralloid roots. A function prediction analysis revealed that endophytic bacteria majorly participated in the plant uptake of phosphorus and metal ions and in disease resistance. These results indicate that the community composition of the bacteria in coralloid roots is affected by both the host and environment, in which the host is more decisive. Despite the very small proportion of core microbes, their interactions are significant and likely contribute to functions related to host survival. Our study contributes to an understanding of microbial diversity and composition in cycads, and it expands the knowledge on the association between hosts and symbiotic microbes.
... Though a comprehensive review of the elemental composition of cycad leaves has been compiled by [28], the role of PGP bacteria on E. villosus nutrition is yet to be studied. Also, many studies reported on the N-fixing bacteria associated with cycad species [25,29,30] however, the influence of the bacterial isolates on plant nutrition and N source reliance is poorly understood. Moreover, studies that report on the composition of the 15 N isotope in cycad foliage, such as [31], do not report on the N reliance and the percentage of N derived from the atmosphere in cycads. ...
Information on how bacteria in plants and soil, along with extracellular enzymes, affect nutrient cycling in Encephalartos villosus growing in nutrient-poor and acidic scarp forests is lacking. Bacteria in coralloid roots, rhizosphere, and non-rhizosphere soils were isolated to determine the potential role of soil bacterial communities and their associated enzyme activities in nutrient contributions in rhizosphere and non-rhizosphere soils. The role of soil characteristics and associated bacteria on E. villosus nutrition and nitrogen source reliance was investigated. Encephalartos villosus leaves, coralloid roots, rhizosphere, and non-rhizosphere soils were collected at two scarp forests. Leaf nutrition, nitrogen source reliance, soil nutrition and extracellular enzyme activities were assayed. A phylogenetic approach was used to determine the evolutionary relationship between identified bacterial nucleotide sequences. Twenty, twelve and seven different bacterial genera were isolated from rhizosphere, non-rhizosphere, and coralloid roots, respectively. Phosphorus and nitrogen cycling enzyme activities in E. villosus rhizosphere and non-rhizosphere soils were insignificant. More than 70% of the leaf nitrogen was derived from the atmosphere. This study revealed that plant-associated bacteria with plant growth-promoting functions, soil bacteria, and associated extracellular enzymes play a role in E. villosus nutrition and nitrogen source reliance and contribute to E. villosus rhizosphere and non-rhizosphere soil nutrition.
... Among symbionts, cycads are the only gymnosperms known to co-exist with Cyanobacteria. The predominant symbiotic Cyanobacteria detected in cycad coralloid roots are mainly reported as Nostoc [25][26][27][28], Calothrix [28,29], Anabaena [30], and Desmonostoc [31]. ...
... Among symbionts, cycads are the only gymnosperms known to co-exist with Cyanobacteria. The predominant symbiotic Cyanobacteria detected in cycad coralloid roots are mainly reported as Nostoc [25][26][27][28], Calothrix [28,29], Anabaena [30], and Desmonostoc [31]. ...
Endophytes are essential in plant succession and evolution, and essential for stress resistance. Coralloid root is a unique root structure found in cycads that has played a role in resisting adverse environments, yet the core taxa and microbial community of different Cycas species have not been thoroughly investigated. Using amplicon sequencing, we successfully elucidated the microbiomes present in coralloid roots of 10 Cycas species, representing all four sections of Cycas in China. We found that the endophytic bacteria in coralloid roots, i.e., Cyanobacteria, were mainly composed of Desmonostoc_PCC-7422, Nostoc_PCC-73102 and unclassified_f__Nostocaceae. Additionally, the Ascomycota fungi of Exophiala, Paraboeremia, Leptobacillium, Fusarium, Alternaria, and Diaporthe were identified as the core fungi taxa. The Ascomycota fungi of Nectriaceae, Herpotrichiellaceae, Cordycipitaceae, Helotiaceae, Diaporthaceae, Didymellaceae, Clavicipitaceae and Pleosporaceae were identified as the core family taxa in coralloid roots of four sections. High abundance but low diversity of bacterial community was detected in the coralloid roots, but no significant difference among species. The fungal community exhibited much higher complexity compared to bacteria, and diversity was noted among different species or sections. These core taxa, which were a subset of the microbiome that frequently occurred in all, or most, individuals of Cycas species, represent targets for the development of Cycas conservation.
... The acetylene reduction rates between the forest and shrub tundra moss populations did not differ statistically in this plants (Warshan et al. 2016(Warshan et al. , 2017de Jesús Suárez-Moo et al. 2019;Bouchard et al. 2020;Holland-Moritz et al. 2021;Alvarenga and Rousk 2022;Renaudin et al. 2022b). Environmental conditions allow some bacteria associated with R. lanuginosum to become abundant in each tundra type. ...
Bryophytes maintain symbiosis with bacteria influencing the local nutrient budget. Moss bacterial communities are composed of a core microbiome and bacteria recruited from environmental sources. Notably, symbiotic N2-fixing bacteria contribute to the N budget in northern ecosystems through biological nitrogen fixation. This process may be affected by the abundance of diazotrophs and moss nutrient content. We used the abundant moss Racomitrium lanuginosum in a forest tundra and shrub tundra in Northern Quebec, Canada, to investigate the bacterial and diazotrophic communities associated with habitat type using amplicon sequencing of the bacterial 16S rRNA and nifH genes and test whether the moss core microbiome has recruitment from the soil bacteria community. The nifH amplicons and element analysis were used to test the effect of diazotrophic abundance and moss nutrient content on N2-fixation activity estimated by acetylene reduction assays. Moss microbial communities between tundra types hosted similar bacterial diversity but differentially abundant groups and characteristic microbial interaction patterns. The core microbiome of R. lanuginosum is composed of bacteria strongly associated with northern mosses with no significant recruitment from the soil. The relative abundances of dominant diazotrophs are significantly correlated with acetylene reduction rates. In contrast, the moss nutrient content did not significantly drive N2-fixation. The proteobacterial genera Azorhizobium and Rhodomicrobium represent newly reported bacteria associated with N2-fixation rates in the tundra. We identified critical bacterial groups related to moss-bacterial symbiosis and N2-fixation in the forest-tundra transition zone, a changing environment susceptible to climate warming.
... lenticels (Bell-Doyon et al., 2020;Rai et al., 2000;Reinke, 1872;Suárez-Moo et al., 2019). The angiosperm Gunnera attracts its cyanobionts through mucilage-filled channels into their stems, where they enter and become intracellular (Khamar et al., 2010;Nilsson et al., 2006;Towata, 1985). ...
... The authors found that there are recurring Rhizobiales in the Azolla leaf pockets. Interestingly, similar presence of Rhizobiales has been reported in the endospheres of the hornwort Leiosporoceros (Bouchard et al., 2020), and the cycads Dioon and Zamia (Bell-Doyon et al., 2020;Suárez-Moo et al., 2019). While these recent microbiome studies suggest that Rhizobiales might have certain significances in plant-cyanobacteria symbiosis, their prevalence and functional roles remain to be tested. ...
Photosynthesis, the ability to fix atmospheric carbon dioxide, was acquired by eukaryotes through symbiosis: the plastids of plants and algae resulted from a cyanobacterial symbiosis that commenced more than 1.5 billion years ago and has chartered a unique evolutionary path. This resulted in the evolutionary origin of plants and algae. Some extant land plants have recruited additional biochemical aid from symbiotic cyanobacteria; these plants associate with filamentous cyanobacteria that fix atmospheric nitrogen. Examples of such interactions can be found in select species from across all major lineages of land plants. The recent rise in genomic and transcriptomic data has provided new insights into the molecular foundation of these interactions. Furthermore, the hornwort Anthoceros has emerged as a model system for the molecular biology of cyanobacteria–plant interactions. Here, we review these developments driven by high-throughput data and pinpoint their power to yield general patterns across these diverse symbioses.
... As such, there was a diversity gradient from bulk soil to roots via the rhizosphere interface. Results were consistent with studies that have demonstrated the highest alpha diversity of both fungi and bacteria in the soil (Lebreton et al., 2019;Suárez-Moo et al., 2019). ...
The occurrence of high- (H) and low- (L) yielding field sites within a farm is a commonly observed phenomenon in soybean cultivation. Site topography, soil physical and chemical attributes, and soil/root-associated microbial composition can contribute to this phenomenon. In order to better understand the microbial dynamics associated with each site type (H/L), we collected bulk soil (BS), rhizosphere soil (RS), and soybean root (R) samples from historically high and low yield sites across eight Pennsylvania farms at V1 (first trifoliate) and R8 (maturity) soybean growth stages (SGS). We extracted DNA extracted from collected samples and performed high-throughput sequencing of PCR amplicons from both the fungal ITS and prokaryotic 16S rRNA gene regions. Sequences were then grouped into amplicon sequence variants (ASVs) and subjected to network analysis. Based on both ITS and 16S rRNA gene data, a greater network size and edges were observed for all sample types from H-sites compared to L-sites at both SGS. Network analysis suggested that the number of potential microbial interactions/associations were greater in samples from H-sites compared to L-sites. Diversity analyses indicated that site-type was not a main driver of alpha and beta diversity in soybean-associated microbial communities. L-sites contained a greater percentage of fungal phytopathogens (ex: Fusarium , Macrophomina , Septoria ), while H-sites contained a greater percentage of mycoparasitic (ex: Trichoderma ) and entomopathogenic (ex: Metarhizium ) fungal genera. Furthermore, roots from H-sites possessed a greater percentage of Bradyrhizobium and genera known to contain plant growth promoting bacteria (ex: Flavobacterium , Duganella ). Overall, our results revealed that there were differences in microbial composition in soil and roots from H- and L-sites across a variety of soybean farms. Based on our findings, we hypothesize that differences in microbial composition could have a causative relationship with observed within-farm variability in soybean yield.
