Soil Origin and Plant Genotype Modulate Switchgrass Aboveground Productivity and Root Microbiome Assembly.

Switchgrass (Panicum virgatum) is a model perennial grass for bioenergy production that can be productive in agricultural lands that are not suitable for food production. There is growing interest in whether its associated microbiome may be adaptive in low- or no-input cultivation systems. However, the relative impact of plant genotype and soil factors on plant microbiome and biomass are a challenge to decouple. To address this, a common garden greenhouse experiment was carried out using six common switchgrass genotypes, which were each grown in four different marginal soils collected from long-term bioenergy research sites in Michigan and Wisconsin. We characterized the fungal and bacterial root communities with high-throughput amplicon sequencing of the ITS and 16S rDNA markers, and collected phenological plant traits during plant growth, as well as soil chemical traits. At harvest, we measured the total plant aerial dry biomass. Significant differences in richness and Shannon diversity across soils but not between plant genotypes were found. Generalized linear models showed an interaction between soil and genotype for fungal richness but not for bacterial richness. Community structure was also strongly shaped by soil origin and soil origin × plant genotype interactions. Overall, plant genotype effects were significant but low. Random Forest models indicate that important factors impacting switchgrass biomass included NO3-, Ca2+, PO43-, and microbial biodiversity. We identified 54 fungal and 52 bacterial predictors of plant aerial biomass, which included several operational taxonomic units belonging to Glomeraceae and Rhizobiaceae, fungal and bacterial lineages that are involved in provisioning nutrients to plants. IMPORTANCE Greenhouse gas reduction, carbon sequestration, and environmental remediation are top research themes within the U.S. Department of Energy funded bioenergy research centers. The utilization of unproductive agricultural land for bioenergy crop production is one of the most promising directions to achieve these goals. Switchgrass is a model biofuel system: it is adapted to a wide variety of geographical regions in North America, it is protective of soil and water resources, and it can be productive in low-fertility soils, but its profitability depends greatly on the biomass yield. Beneficial microbes have known roles in modulating plant biomass production but their interaction with soil geography, and switchgrass cultivars were not thoroughly studied. This study aims to fill important knowledge gaps and to serve as a foundation for switchgrass biomass promotion through microbe selection with an ultimate goal of facilitating sustainable bioenergy crop production.

Maple and hickory leaf litter fungal communities reflect pre-senescent leaf communities.

Fungal communities are known to contribute to the functioning of living plant microbiomes as well as to the decay of dead plant material and affect vital ecosystem services, such as pathogen resistance and nutrient cycling. Yet, factors that drive structure and function of phyllosphere mycobiomes and their fate in leaf litter are often ignored. We sought to determine the factors contributing to the composition of communities in temperate forest substrates, with culture-independent amplicon sequencing of fungal communities of pre-senescent leaf surfaces, internal tissues, leaf litter, underlying humus soil of co-occurring red maple (Acer rubrum) and shagbark hickory (Carya ovata). Paired samples were taken at five sites within a temperate forest in southern Michigan, USA. Fungal communities were differentiable based on substrate, host species, and site, as well as all two-way and three-way interactions of these variables. PERMANOVA analyses and co-occurrence of taxa indicate that soil communities are unique from both phyllosphere and leaf litter communities. Correspondence of endophyte, epiphyte, and litter communities suggests dispersal plays an important role in structuring fungal communities. Future work will be needed to assess how this dispersal changes microbial community functioning in these niches.

The role of bilateral adrenalectomy in the treatment of congenital adrenal hyperplasia.

This report summarizes follow-up studies in 18 patients who underwent bilateral adrenalectomy for congenital adrenal hyperplasia. Three of these patients were young children with null/null mutations of CYP21, and the other 15 were adrenalectomized because of difficulties in their management on conventional therapy. The average duration of follow-up was 59 months and represents an aggregate of 90 postoperative years. The adrenals were removed laparoscopically in 13 patients and by open flank incisions in five. Adrenal crises associated with severe illnesses occurred in five patients at times when their glucocorticoid substitution was suboptimal. All were responsive to appropriate therapy. Two of these patients were young children who had hypoglycemia during gastroenteritis or febrile illness associated with poor food intake or vomiting. Significant elevations of adrenal steroid precursors, presumably from ectopic adrenal rests, were observed postoperatively in eight of the patients. Patients and parents were nearly unanimous in their enthusiasm for adrenalectomy. In most, signs of androgen excess have decreased, and obesity has become less of a problem with lowering the dose of glucocorticoid. We conclude that adrenalectomy is a safe and efficacious method of managing congenital adrenal hyperplasia in selected patients. Prophylactic adrenalectomy in young children with double null mutations remains experimental.