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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2020

Abstract

Recent discoveries have highlighted multiple mitotically and meiotically inherited alterations in gene expression that could not be explained solely by changes in the DNA sequence but were acknowledged as epigenetic. The modern view on epigenetics considers it as an integral part of genetics. Epigenetic mechanisms are encoded by genes in the genome and contribute to an essential part of genomic diversity, significantly extending its regulatory abilities. Epigenetic mechanisms involve molecular chromatin alterations through DNA methylation and histone modifications, as well as, complex non-coding RNAs and related enzyme machinery leading to changes in gene expression and resulting in changing phenotypes. In plants, epigenetic mechanisms may occur over their lifetime and across multiple generations, and can contribute substantially to phenotypic plasticity, stress responses, disease resistance, acclimation and adaptation to habitat conditions. In this review, we summarize recent advances with regards to Norway spruce epigenomics. We first consider the large size of the spruce genome that is linked to epigenetic mechanisms and why epigenomics is vitally important for spruce. Then, we discuss the molecular machinery supporting epigenetic mechanisms in Norway spruce and putative gene models involved. We presume substantial extension of gene families of epigenetic regulators and non-coding RNAs, especially in reproductive tissues. Norway spruce was the first species among forest trees in which epigenetic memory and epigenetic mechanisms were studied. The induction of an epigenetic memory during sexual reproduction and somatic embryogenesis has been described in Norway spruce. We discuss the latest results of epigenomic variation and epigenetic memory studies in Norway spruce and define the future perspectives for epigenetic studies. However, there is still a long way to decipher how the epigenetic mechanisms are involved in maintaining the stability of the spruce epigenome, how the epigenome is set to produce the epigenetic memory phenomenon and how these may result in an increased rate of adaptation to a changing environment.

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Abstract

Many of the world’s peatlands have been affected by water table drawdown and subsequent loss of organic matter. Rewetting has been proposed as a measure to restore peatland functioning and to halt carbon loss, but its effectiveness is subject to debate. An important prerequisite for peatland recovery is a return of typical microbial communities, which drive key processes. To evaluate the effect of rewetting, we investigated 13 fen peatland areas across a wide (>1500 km) longitudinal gradient in Europe, in which we compared microbial communities between drained, undrained, and rewetted sites. There was a clear difference in microbial communities between drained and undrained fens, regardless of location. Community recovery upon rewetting was substantial in the majority of sites, and predictive functional profiling suggested a concomitant recovery of biogeochemical peatland functioning. However, communities in rewetted sites were only similar to those of undrained sites when soil organic matter quality (as expressed by cellulose fractions) and quantity were still sufficiently high. We estimate that a minimum organic matter content of ca. 70% is required to enable microbial recovery. We conclude that peatland recovery after rewetting is conditional on the level of drainage-induced degradation: severely altered physicochemical peat properties may preclude complete recovery for decades.

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Abstract

No abstract has been registered

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Abstract

No abstract has been registered

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Abstract

Degraded tropical forests that were converted into pastures dominated by exotic grasses are a challenge for restoration due to arrested succession. Nucleation is a suitable strategy to restore such abandoned pastures as it can overcome seed and site limitation, and would foster the recovery of structural, functional, and species diversity. To explore the outcomes of different nucleation techniques in terms of richness, functional diversity, resource offer, and species and trait composition during the first year after implementation in an abandoned pasture in the tropical Andes, we conducted a field experiment with four nucleation treatments established in 1-m2 subplots, i.e. natural regeneration (control), seed rain transfer, seed bank transfer, and pre-grown plant mats. Number of species, functional diversity, proportion of natives, flowering and fruiting were response variables of the nucleation treatments and time since restoration using linear mixed-effects models. Species and trait composition trajectories over time were depicted with NMDS. Species richness and functional diversity of understory vegetation increased over time and with nucleation, being significantly higher by the final survey. Seed bank transfer introduced most species to the area in comparison to natural regeneration. Functional diversity, proportion of native, flowering, and fruiting species changed with time albeit with no differences among treatments. Species and trait composition showed convergence over time, which stresses the strong influence of environmental filtering in early restoration of abandoned pastures. Although positive aspects of planting trees and shrubs cannot be neglected, we argue that the incorporation of (several) more sophisticated nucleation techniques is beneficial for restoration of tropical forests.