Endophytic and epiphytic phyllosphere fungal communities are shaped by different environmental factors in a mediterranean ecosystem

The online version of this article (https://doi.org/10.1007/s00248-018-1161-9) contains supplementary material, which is available to authorized users.The diversity and factors influencing fimgal assemblages in phyllosphere of Mediterranean tree species have been barely studied, especially when endophytic and epiphytic communities are simultaneously considered. In this work, the endophytic and epiphytic fungal communities from olive tree phyllosphere were studied. This tree species is natural from the Mediterranean region and adapted to grow under adverse climatic conditions. The main objectives were to determine whether there are differences between both fungal communities and to examine whether different abiotic (climate-related) and biotic (plant organs) factors play a pivotal role in structuring these communities. Both communities differed in size and composition, with epiphytic community being richer and more abundant, displaying also a dominance of melanized fungi. Season was the major driver of community composition, especially of epiphytes. Other drivers shaping epiphytes were wind speed and temperature, while plant organ, rainfall, and temperature were the major drivers for endophytic composition. In contrast, canopy orientation caused slight variations in community composition of fungi, but with distinct effects in spring and autumn seasons. In conclusion, epiphytic and endophytic communities are not driven by the same factors. Several sources of variation undergo complex interactions to form and maintain phyllosphere fungal community in Mediterranean climates. Climatic parameters have influence on these fungal communities, suggesting that they are likely to be affected by climate changes in a near future.This work is funded by FEDER funds through COMPETE (Programa Operacional Factores de Competitividade) and by national funds by FCT (Fundacao para a Ciencia e a Tecnologia) within the framework of the project EXCL/AGR-PRO/0591/2012. T. Gomes thanks FCT, POPH-QREN, and FSE for PhD SFRH/BD/98127/2013 grant

Simulated Atmospheric N Deposition Alters Fungal Community Composition and Suppresses Ligninolytic Gene Expression in a Northern Hardwood Forest

High levels of atmospheric nitrogen (N) deposition may result in greater terrestrial carbon (C) storage. In a northern hardwood ecosystem, exposure to over a decade of simulated N deposition increased C storage in soil by slowing litter decay rates, rather than increasing detrital inputs. To understand the mechanisms underlying this response, we focused on the saprotrophic fungal community residing in the forest floor and employed molecular genetic approaches to determine if the slower decomposition rates resulted from down-regulation of the transcription of key lignocellulolytic genes, by a change in fungal community composition, or by a combination of the two mechanisms. Our results indicate that across four Acer-dominated forest stands spanning a 500-km transect, community-scale expression of the cellulolytic gene cbhI under elevated N deposition did not differ significantly from that under ambient levels of N deposition. In contrast, expression of the ligninolytic gene lcc was significantly down-regulated by a factor of 2–4 fold relative to its expression under ambient N deposition. Fungal community composition was examined at the most southerly of the four sites, in which consistently lower levels of cbhI and lcc gene expression were observed over a two-year period. We recovered 19 basidiomycete and 28 ascomycete rDNA 28S operational taxonomic units; Athelia, Sistotrema, Ceratobasidium and Ceratosebacina taxa dominated the basidiomycete assemblage, and Leotiomycetes dominated the ascomycetes. Simulated N deposition increased the proportion of basidiomycete sequences recovered from forest floor, whereas the proportion of ascomycetes in the community was significantly lower under elevated N deposition. Our results suggest that chronic atmospheric N deposition may lower decomposition rates through a combination of reduced expression of ligninolytic genes such as lcc, and compositional changes in the fungal community

Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica)

We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acerplatanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter, and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity itself

Hypocrea rufa/Trichoderma viride: a reassessment, and description of five closely related species with and without warted conidia

The type species of the genus Hypocrea (Hypocreaceae, Hypocreales, Ascomycota, Fungi), H. rufa, is re-defined and epitypified using a combination of phenotype (morphology of teleomorphs and anamorphs, and characteristics in culture) and phylogenetic analyses of the translation-elongation factor 1α gene. Its anamorph, T. viride, the type species of Trichoderma, is re-described and epitypified. Eidamia viridescens is combined as Trichoderma viridescens and is recognised as one of the most morphologically and phylogenetically similar relatives of T. viride. Its teleomorph is newly described as Hypocrea viridescens. Contrary to frequent citations of H. rufa and T. viride in the literature, this species is relatively rare. Although both T. viride and T. viridescens have a wide geographic distribution, their greatest genetic diversity appears to be in Europe and North America. Hypocrea vinosa is characterised and its anamorph, T. vinosum sp. nov., is described. Conidia of T. vinosum are subglobose and warted. The new species T. gamsii is proposed. It shares eidamia-like morphology of conidiophores with T. viridescens, but it has smooth, ellipsoidal conidia that have the longest L/W ratio that we have seen in Trichoderma. Trichoderma scalesiae, an endophyte of trunks of Scalesia pedunculata in the Galapagos Islands, is described as new. It only produces conidia on a low-nutrient agar to which filter paper has been added. Additional phylogenetically distinct clades are recognised and provisionally delimited from the species here described. Trichoderma neokoningii, a T. koningii-like species, is described from a collection made in Peru on a fruit of Theobroma cacao infected with Moniliophthora roreri

Paradox as a Metatheoretical Perspective

Organizations are rife with tensions – flexibility vs. control, exploration vs. exploitation, autocracy vs. democracy, social vs. financial, global vs. local. Researchers have long responded using contingency theory, asking “under what conditions should managers emphasize either A or B?” Yet increasingly studies apply a paradox perspective, shifting the question to: “how can we engage both A and B simultaneously?” Despite accumulating exemplars, commonalities across paradox studies remain unclear, and ties unifying this research community weak. To energize further uses of a paradox perspective, we build from past reviews to explicate its role as a metatheory. Contrasting this lens to contingency theory, we illustrate its meta-theoretical nature. We then dive deeper to sharpen the focus and widen the scope of a paradox perspective. Identifying core elements viewed from a paradox perspective – underlying assumptions, central concepts, nature of interrelationships and boundary conditions – offers a guide, informing the practice of paradox research. Next, we illustrate diverse uses of this lens. We conclude by exploring implications and next steps, stressing the rising need for paradox research, as complexity, change and ambiguity intensify demands for both/and approaches in theory and practice

Genetic polymorphisms of the RAS-cytokine pathway and chronic kidney disease

Chronic kidney disease (CKD) in children is irreversible. It is associated with renal failure progression and atherosclerotic cardiovascular (CV) abnormalities. Nearly 60% of children with CKD are affected since birth with congenital or inherited kidney disorders. Preliminary evidence primarily from adult CKD studies indicates common genetic risk factors for CKD and atherosclerotic CV disease. Although multiple physiologic pathways share common genes for CKD and CV disease, substantial evidence supports our attention to the renin angiotensin system (RAS) and the interlinked inflammatory cascade because they modulate the progressions of renal and CV disease. Gene polymorphisms in the RAS-cytokine pathway, through altered gene expression of inflammatory cytokines, are potential factors that modulate the rate of CKD progression and CV abnormalities in patients with CKD. For studying such hypotheses, the cooperative efforts among scientific groups and the availability of robust and affordable technologies to genotype thousands of single nucleotide polymorphisms (SNPs) across the genome make genome-wide association studies an attractive paradigm for studying polygenic diseases such as CKD. Although attractive, such studies should be interpreted carefully, with a fundamental understanding of their potential weaknesses. Nevertheless, whole-genome association studies for diabetic nephropathy and future studies pertaining to other types of CKD will offer further insight for the development of targeted interventions to treat CKD and associated atherosclerotic CV abnormalities in the pediatric CKD population

Paradox Research in Management Science: Looking Back to Move Forward

Paradox studies offer vital and timely insights into an array of organizational tensions. Yet this field stands at a critical juncture. Over the past 25 years, management scholars have drawn foundational insights from philosophy and psychology to apply a paradox lens to organizational phenomena. Yet extant studies selectively leverage ancient wisdom, adopting some key insights while abandoning others. Using a structured content analysis to review the burgeoning management literature, we surface six key themes, which represent the building blocks of a meta-theory of paradox. These six themes received varying attention in extant studies: paradox scholars emphasize types of paradoxes, collective approaches, and outcomes, but pay less attention to relationships within paradoxes, individual approaches, and dynamics. As this analysis suggests, management scholars have increasingly simplified the intricate, often messy phenomena of paradox. Greater simplicity renders phenomena understandable and testable, however, oversimplifying complex realities can foster reductionist and incomplete theories. We therefore propose a future research agenda targeted at enriching a meta-theory of paradox by reengaging these less developed themes. Doing so can sharpen the focus of this field, while revisiting its rich conceptual roots to capture the intricacies of paradox. This future research agenda leverages the potential of paradox across diverse streams of management science