Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Genetic linkage mapping at higher ploidy levels using polymap R
Bourke, Peter - \ 2019
Flower movement balances pollinator needs and pollen protection
Haverkamp, Alexander ; Li, Xiang ; Hansson, Bill S. ; Baldwin, Ian T. ; Knaden, Markus ; Yon, Felipe - \ 2019
Ecology 100 (2019)1. - ISSN 0012-9658
flower handling - flower orientation - Manduca - Nicotiana - pollen viability - pollination

Flower signaling and orientation are key characteristics that determine a flower's pollinator guild. However, many flowers actively move during their daily cycle, changing both their detectability and accessibility to pollinators. The flowers of the wild tobacco Nicotiana attenuata orientate their corolla upward at sunset and downward after sunrise. Here, we investigated the effect of different flower orientations on a major pollinator of N. attenuata, the hawkmoth Manduca sexta. We found that although flower orientation influenced the flight altitude of the moth in respect to the flower, it did not alter the moth's final flower choice. These behavioral observations were consistent with the finding that orientation did not systematically change the spatial distribution of floral volatiles, which are major attractants for the moths. Moreover, hawkmoths invested the same amount of time into probing flowers at different orientations, even though they were only able to feed and gather pollen from horizontally and upward-oriented flowers, but not from downward-facing flowers. The orientation of the flower was hence crucial for a successful interaction between N. attenuata and its hawkmoth pollinator. Additionally, we also investigated potential adverse effects of exposing flowers at different orientations to natural daylight levels, finding that anther temperature of upward-oriented flowers was more than 7°C higher than for downward-oriented flowers. This increase in temperature likely caused the significantly reduced germination success that was observed for pollen grains from upward-oriented flowers in comparison to those of downward and horizontally oriented flowers. These results highlight the importance of flower reorientation to balance pollen protection and a successful interaction of the plant with its insect pollinators by maintaining the association between flower volatiles and flower accessibility to the pollinator.

Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) – A review
Işıldar, Arda ; Hullebusch, Eric D. van; Lenz, Markus ; Laing, Gijs Du; Marra, Alessandra ; Cesaro, Alessandra ; Panda, Sandeep ; Akcil, Ata ; Kucuker, Mehmet Ali ; Kuchta, Kerstin - \ 2019
Journal of Hazardous Materials 362 (2019). - ISSN 0304-3894 - p. 467 - 481.
Bioleaching - Bioprecipitation - Biosorption - Biotechnologies - Critical metals - Electronic waste

Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to recycle metals from WEEE. These processes are deemed imperfect, energy-intensive and non-selective towards CRMs. Biotechnologies are a promising alternative to the current industrial best available technologies (BAT). In this review, we present the current frontiers in CRMs recovery from WEEE using biotechnology, the biochemical fundamentals of these bio-based technologies and discuss recent research and development (R&D) activities. These technologies encompass biologically induced leaching (bioleaching) from various matrices,biomass-induced sorption (biosorption), and bioelectrochemical systems (BES).

Unfolding plant desiccation tolerance : evolution, structure, and function of LEA proteins
Silva Artur, Mariana Aline - \ 2019
Wageningen University. Promotor(en): Henk Hilhorst, co-promotor(en): Wilco Ligterink. - Wageningen : Wageningen University - ISBN 9789463433860 - 174
Light regulation of vitamin C in tomato fruit is mediated through photosynthesis
Ntagkas, Nikolaos ; Woltering, Ernst ; Nicole, Celine ; Labrie, Caroline ; Marcelis, Leo F.M. - \ 2019
Environmental and Experimental Botany 158 (2019). - ISSN 0098-8472 - p. 180 - 188.
Ascorbic acid - Irradiance - Photosynthesis - Respiration - Spectrum - Vitamin C

Higher levels of irradiance result in higher accumulation of ascorbate in leaves and fruits. Photosynthesis and respiration are an integral part of the physiological mechanism of light regulation of ascorbate in leaves, but little is known about the light regulation of ascorbate in fruit. The aim of this study was to investigate whether fruit illumination alone is sufficient for ascorbate increase in tomato fruit and whether this light signal is mediated by respiration and photosynthesis. First the changes of ascorbate with the progress of fruit development were investigated and subsequently detached fruit of different tomato genotypes were exposed to different irradiances and spectra. Measurements were performed on ascorbate, respiration, photosynthesis and chlorophyll content of the fruit. When attached to the plant, there was no effect of development on ascorbate from the mature green to the red stage. Detached fruit stored in darkness did not accumulate ascorbate. However, when exposed to 300–600 μmol m−2 s-1 light detached mature green fruit (photosynthetically active) substantially accumulated ascorbate, while mature red fruit (non-photosynthetically active) did not respond to light. Photosynthesis correlated with this increase of ascorbate while no correlation between respiration and ascorbate was found. Spectral effects on ascorbate in detached tomato fruit were limited. These results indicate that the signal for light regulation of ascorbate is perceived locally in the fruit and that fruit illumination alone is sufficient for a considerable increase in ascorbate levels for as long as the fruit contains chlorophyll. It is shown that photosynthetic activity of the fruit is an integral part of the response of ascorbate to light in tomato fruit. The light induced increase in ascorbate levels occurred in a range of genotypes, indicating a universal effect of light to ascorbate in tomato fruit.

Ecological intensification by integrating biogas production into nutrient cycling : Modeling the case of Agroecological Symbiosis
Koppelmäki, Kari ; Parviainen, Tuure ; Virkkunen, Elina ; Winquist, Erika ; Schulte, Rogier P.O. ; Helenius, Juha - \ 2019
Agricultural Systems 170 (2019). - ISSN 0308-521X - p. 39 - 48.
Biological nitrogen fixation - Localized agrifood system - Nutrient losses - Organic farming - Renewable energy - Sustainable intensification

There is growing demand to produce both food and renewable energy in a sustainable manner, while avoiding competition between food and energy production. In our study, we investigated the potential of harnessing biogas production into nutrient recycling in an integrated system of organic food production and food processing. We used the case of Agroecological Symbiosis (AES) at Palopuro, which is a combination of three farms, a biogas plant, and a bakery, as a case to explore how biogas production using feedstocks from the farms can be used to improve nutrient cycling, and to calculate how much energy could be produced from the within-system feedstocks. The current system (CS) used in organic farms, and the integrated farm and food processing AES system, were analyzed using Substance Flow analysis. In the AES, annual nitrogen (N) and phosphorus (P) surpluses were projected to be reduced from 95 kg ha−1 to 36 kg ha−1 and from 3.4 kg ha−1 to −0.5 kg ha−1 respectively, compared to the CS. Biogas produced from green manure leys as the major feedstock, produced 2809 MWh a−1. This was 70% more than the energy consumed (1650 MWh a−1) in the systemand thus the AES system turned out to be a net energy producer. Results demonstrated the potential of biogas production to enhance the transition to bioenergy, nutrient recycling, and crop productivity in renewable localized farming and food systems.

A Robust Auxin Response Network Controls Embryo and Suspensor Development through a bHLH Transcriptional Module
Radoeva, T.M. ; Boekschoten, M.V. ; Hooiveld, G.J.E.J. ; Weijers, D. - \ 2019
GSE69700 - PRJNA286216 - Arabidopsis thaliana
Land plants can reproduce sexually by developing an embryo from a fertilized egg cell. However, embryos can also be formed from other cell types in many plant species. A key question is thus how embryo identity in plants is controlled, and how this process is modified during non-zygotic embryogenesis. The Arabidopsis zygote divides to produce an embryonic lineage and an extra-embryonic suspensor. Yet, normally quiescent suspensor cells can develop a second embryo when the initial embryo is damaged, or when response to the signaling molecule auxin is locally blocked. Here we have used auxin-dependent suspensor embryogenesis as a model to determine transcriptome changes during embryonic reprogramming. We find that reprogramming is complex and accompanied by large transcriptomic changes prior to anatomic changes. This analysis revealed a strong enrichment for genes encoding components of auxin homeostasis and response among misregulated genes. Strikingly, deregulation among multiple auxin-related gene families converged upon re-establishment of cellular auxin levels or response. This suggests a remarkable degree of feedback regulation to create resilience in auxin response during embryo development. Starting from the transcriptome of auxin-deregulated embryos, we identify an auxin-dependent bHLH transcription factor network that mediates the activity of this hormone in suppressing embryo development from the suspensor.
Building a Market for New Meat Alternatives: Business Activity and Consumer Appetite in the Netherlands
Dagevos, H. ; Tolonen, Ella ; Quist, Jaco - \ 2019
In: Environmental, Health, and Business Opportunities in the New Meat Alternatives Market / Bogueva, Diana, Marinova, Dora, Raphaely, Talia, Schmidinger, Kurt, IGI Global - ISBN 9781522573500 - p. 183 - 201.
This chapter provides an overview of developments in the Netherlands on new meat alternatives with a focus on plant-based meat substitutes and lab-grown meat. It devotes attention to both the supply side of the market (business activity) and the demand side (consumer appetite). The first concerns developments in the meat substitutes' innovation system since the 1990s until now. It concludes that the Netherlands has become a major player. The latter concerns the supportive purchasing power of consumers regarding the building of a viable and strong market for new meat alternatives. It is concluded that available consumer studies provide evidence for being cautiously optimistic. The closing parts of this chapter, however, bring to the fore that a transition from the current high-meat diets to more sustainable and healthier diets with more non-meat sources of proteins is anything but self-evident. However encouraging and energetic modern developments in the Netherlands are, much progress is needed as it comes to consumer acceptance of new meat alternatives, producer capacity to innovate, concentrate strengths, and capture market share, as well as governmental support for reducing the adverse effects of today's meat consumption and production levels in accordance with Sustainable Development Goal 12 concerning responsible consumption and production.
The emulsifying performance of mildly derived mixtures from sunflower seeds
Karefyllakis, Dimitris ; Octaviana, Heidi ; Goot, Atze Jan van der; Nikiforidis, Constantinos V. - \ 2019
Food Hydrocolloids 88 (2019). - ISSN 0268-005X - p. 75 - 85.
Emulsions - Mixtures - Plant proteins - Sunflower press cake - Sunflower seeds

Sustainability driven production of food ingredients is in the center of discussion the past years, with plants being a promising source, since they are widely available and have smaller environmental impact compared to animals. However, plant material consists of a sturdy configuration comprising many components, like proteins, which cannot be readily liberated. Thus, downstream processing of plants often involves intensive physicochemical and thermal processing, which might be accompanied by alteration of protein properties, like emulsification ability. Here, the aim was to investigate the emulsification ability of the native mixtures derived from sunflower seeds, obtained via simple separation steps and link their properties with their molecular composition. The investigated molecular mixtures were the cold-pressed sunflower cake, a protein-based and a fibre-based mixture. It was demonstrated that the residual oil in both the Sf cake and the protein-based mixture was present in the form of naturally emulsified oil droplets, so-called oil bodies. Oil bodies did not have a notable impact on the interfacial activity of the samples in contrast with the destabilization effect of polysaccharides. Despite their complex composition all mixtures could efficiently stabilize oil/water interfaces, showing similar properties compared to isolated proteins. This is an intriguing bottom line regarding the necessity for using pure emulsifiers. The findings prove that molecular mixtures which contain even minor amounts of proteins, can be used as ingredients for efficient emulsion stabilization.

The SAUR gene family: the plant’s toolbox for adaptation of growth and development
Stortenbeker, Niek ; Bemer, M. - \ 2019
Journal of Experimental Botany 70 (2019)1. - ISSN 0022-0957 - p. 17 - 27.
The family of small auxin up-regulated RNA (SAUR) genes is a family of auxin-responsive genes with ~60–140 members in most higher plant species. Despite the early discovery of their auxin responsiveness, their function and mode
of action remained unknown for a long time. In recent years, the importance of SAUR genes in the regulation of dynamic and adaptive growth, and the molecular mechanisms by which SAUR proteins act are increasingly well understood. SAURs play a central role in auxin-induced acid growth, but can also act independently of auxin, tissue specifically regulated by various other hormone pathways and transcription factors. In this review, we summarize recent advances in the characterization of the SAUR genes in Arabidopsis and other plant species. We particularly elaborate on their capacity to fine-tune growth in response to internal and external signals, and discuss the breakthroughs in understanding the mode of action of SAURs in relation to their complex regulation.
Sporocadaceae, a family of coelomycetous fungi with appendage-bearing conidia
Liu, F. ; Bonthond, G. ; Groenewald, J.Z. ; Cai, L. ; Crous, P.W. - \ 2019
Studies in Mycology 92 (2019). - ISSN 0166-0616 - p. 287 - 415.
Multi-locus phylogeny - New taxa - Seimatosporium - Sporocadus - Taxonomy

Species of Sporocadaceae are endophytic, plant pathogenic or saprobic, and associated with a wide range of host plants. Recent molecular studies that have attempted to address familial and generic boundaries of fungi belonging to Sporocadaceae were based on a limited number of samples and DNA loci. The taxonomy of this group of fungi is therefore still not fully resolved. The aim of the present study is to provide a natural classification for the Sporocadaceae based on multi-locus phylogenetic analyses, using LSU, ITS, tef-1α tub2 and rpb2 loci, in combination with morphological data. A total of 30 well-supported monophyletic clades in Sporocadaceae are recognised, representing 23 known and seven new genera. Typifications are proposed for the type species of five genera (Diploceras, Discosia, Monochaetia, Sporocadus and Truncatella) to stabilise the application of these names. Furthermore, Neotruncatella and Dyrithiopsis are synonymised under Hymenopleella, and the generic circumscriptions of Diploceras, Disaeta, Hymenopleella, Monochaetia, Morinia, Pseudopestalotiopsis, Sarcostroma, Seimatosporium, Synnemapestaloides and Truncatella are emended. A total of 51 new species, one nomina nova and 15 combinations are introduced.

Comparison of ammonia emissions related to nitrogen use efficiency of livestock production in Europe
Groenestein, C.M. ; Hutchings, N.J. ; Haenel, H.D. ; Amon, B. ; Menzi, H. ; Mikkelsen, M.H. ; Misselbrook, T.H. ; Bruggen, C. van; Kupper, T. ; Webb, J. - \ 2019
Journal of Cleaner Production 211 (2019). - ISSN 0959-6526 - p. 1162 - 1170.
Ammonia emission intensity - Animal protein - Feed nitrogen - Manure management - Nitrogen use efficiency

The increasing global demand for food and the environmental effects of reactive nitrogen losses in the food production chain, increase the need for efficient use of nitrogen (N). Of N harvested in agricultural plant products, 80% is used to feed livestock. Because the largest atmospheric loss of reactive nitrogen from livestock production systems is ammonia (NH3), the focus of this paper is on N lost as NH3 during the production of animal protein. The focus of this paper is to understand the key factors explaining differences in Nitrogen Use Efficiency (NUE) of animal production among various European countries. Therefore we developed a conceptual framework to describe the NUE defined as the amount of animal-protein N per N in feed and NH3–N losses in the production of milk, beef, pork, chicken meat and eggs in The Netherlands, Switzerland, United Kingdom, Germany, Austria and Denmark. The framework describes how manure management and animal-related parameters (feed, metabolism) relate to NH3 emissions and NUE. The results showed that the animal product with the lowest NUE had the largest NH3 emissions and vice versa, which agrees with the reciprocal relationship between NUE and NH3 within the conceptual framework. Across animal products for the countries considered, about 20% of the N in feed is lost as NH3. The significant smallest proportion (12%) of NH3–N per unit of Nfeed is from chicken production. The proportions for other products are 17%, 19%, 20% and 22% for milk, pork, eggs and beef respectively. These differences were not significantly different due to the differences among countries. For all countries, NUE was lowest for beef and highest for chicken. The production of 1 kg N in beef required about 5 kg N in feed, of which 1 kg N was lost as NH3–N. For the production of 1 kg N in chicken meat, 2 kg N in feed was required and 0.2 kg was lost as NH3. The production of 1 kg N in milk required 4 kg N in feed with 0.6 kg NH3–N loss, the same as pork and eggs, but those needed 3 and 3.5 kg N in feed per kg N in product respectively. Except for beef, the differences among these European countries were mainly caused by differences in manure management practices and their emission factors, rather than by animal-related factors including feed and digestibility influencing the excreted amount of ammoniacal N (TAN). For beef, both aspects caused important differences. Based on the results, we encourage the expression of N losses as per N in feed or per N in product, in addition to per animal place, when comparing production efficiency and NUE. We consider that disaggregating emission factors into a diet/animal effect and a manure management effect would improve the basis for comparing national NH3 emission inventories.

Photo-stability of a flavonoid dye in presence of aluminium ions
Villela, Alexandre ; Vuuren, Monique S.A. van; Willemen, Hendra M. ; Derksen, Goverdina C.H. ; Beek, Teris A. van - \ 2019
Dyes and Pigments 162 (2019). - ISSN 0143-7208 - p. 222 - 231.
Flavonoid - Light-fastness - Luteolin - Natural dye - Reseda luteola - Weld

The main colouring compounds of the dye plant weld (Reseda luteola L.) are the flavones luteolin (lut), lut-7-O-glucoside and lut-7,3ʹ-O-diglucoside. Alum (an aluminium salt)-premordanted wool dyed with weld leads to yellow colours that are of low resistance to light. The photo-stability of lut in aerated methanol–water 8:2 (v/v) solution upon irradiation with light above 300 nm was studied at different lut–Al3+ ratios. Experiments using extracts of weld to dye wool premordanted with increasing quantities of aluminium salts were also carried out. The photo-stability of lut in the polar protic solvent and the photo-resistance (light-fastness) of the colour of weld-dyed wool decrease with increasing concentrations of aluminium ions. Thus, the lower the [Al3+] used for mordanting the wool, the more light-fast its colour. Lowering the [Al3+] appears to have no negative influence on the wash-fastness of the colour. As the gain in light-fastness by the use of low [Al3+] to premordant the wool is not extensive, however, this does not seem to be a way to meet today's requirement of light-fastness of the colours of dyed textiles by itself. Nevertheless, it may be part of a bigger strategy to address the need for increased light-fastness of the colour of wool dyed with weld. Implementation of this approach by dyers is expected to clarify whether it results in benefits for textile dyeing practice.

Atmospheric nitrogen deposition impacts on the structure and function of forest mycorrhizal communities : A review
Lilleskov, Erik A. ; Kuyper, Thomas W. ; Bidartondo, Martin I. ; Hobbie, Erik A. - \ 2019
Environmental Pollution 246 (2019). - ISSN 0269-7491 - p. 148 - 162.
Community response - Critical loads - Function - Mycorrhizal fungi - Nitrogen deposition

Humans have dramatically increased atmospheric nitrogen (N) deposition globally. At the coarsest resolution, N deposition is correlated with shifts from ectomycorrhizal (EcM) to arbuscular mycorrhizal (AM) tree dominance. At finer resolution, ectomycorrhizal fungal (EcMF) and arbuscular mycorrhizal fungal (AMF) communities respond strongly to long-term N deposition with the disappearance of key taxa. Conifer-associated EcMF are more sensitive than other EcMF, with current estimates of critical loads at 5–6 kg ha−1 yr−1 for the former and 10–20 kg ha−1 yr−1 for the latter. Where loads are exceeded, strong plant-soil and microbe-soil feedbacks may slow recovery rates after abatement of N deposition. Critical loads for AMF and tropical EcMF require additional study. In general, the responses of EcMF to N deposition are better understood than those of AMF because of methodological tractability. Functional consequences of EcMF community change are linked to decreases by fungi with medium-distance exploration strategies, hydrophobic walls, proteolytic capacity, and perhaps peroxidases for acquiring N from soil organic matter. These functional losses may contribute to declines in forest floor decomposition under N deposition. For AMF, limited capacity to directly access complexed organic N may reduce functional consequences, but research is needed to test this hypothesis. Mycorrhizal biomass often declines with N deposition, but the relative contributions of alternate mechanisms for this decline (lower C supply, higher C cost, physiological stress by N) have not been quantified. Furthermore, fungal biomass and functional responses to N inputs probably depend on ecosystem P status, yet how N deposition-induced P limitation interacts with belowground C flux and mycorrhizal community structure and function is still unclear. Current ‘omic analyses indicate potential functional differences among fungal lineages and should be integrated with studies of physiology, host nutrition, growth and health, fungal and plant community structure, and ecosystem processes. Forest mycorrhizal fungal community composition responds strongly to N deposition across broad ranges of spatial, temporal and phylogenetic scales, with functional consequences—including altered tree nutrition and C, N, and P cycling—that are substantial but only partially understood.

Water resource potential for large-scale sweet sorghum production as bioenergy feedstock in Northern China
Fu, Hai Mei ; Chen, Yan Hua ; Yang, Xiao Mei ; Di, Jia Ying ; Xu, Ming Gang ; Zhang, Bao Gui - \ 2019
Science of the Total Environment 653 (2019). - ISSN 0048-9697 - p. 758 - 764.
Arid and semi-arid conditions - Bioenergy - Marginal lands - Sweet sorghum - Water resource potential

This study investigated the water resource potential for bioenergy production from sweet sorghum (Sorghum bicolor (L.)) in Northern China according to the distribution of water resources, climate conditions and the total water consumption of bioenergy based on sweet sorghum, which consisted of blue water, green water and grey water. At a case study site in Inner Mongolia, simulation with a plant phenological model was used to determine whether sweet sorghum could reach the harvestable stage for sugar juice production. The blue water in the agricultural phase was estimated according to the potential crop evapotranspiration (ETc), the drought sensitivity of sweet sorghum in different stages and the precipitation during the growing season. The results showed that the irrigation water was significantly different among the districts, ranging from 730 to 5500 m3/ha and 2060 to 6680 m3/ha for early-maturing and late-maturing varieties, respectively. To avoid the water pressure level to be exacerbated and the severe reallocation of water resources resulting in negative effects on other sectors, the maximal annual water withdrawal was set to not surpass the upper threshold of water stress level of 40%. That makes the maximum area for the production of sweet sorghum cannot exceed 1.95 × 104 ha, representing only 0.24% of the total marginal land area in Inner Mongolia. However, the economic benefits of bioenergy production from sweet sorghum would be negative due to the high labour input. Therefore, not only the availability of marginal land, the climate conditions and local water resources but also the improvement of mechanisation and agricultural production techniques should be considered to attain the sustainable development of bioenergy production and address global energy and environmental crises.

A new satellite-based indicator to identify spatiotemporal foraging areas for herbivorous waterfowl
Wei, Jie ; Xin, Qinchuan ; Ji, Luyan ; Gong, Peng ; Si, Yali - \ 2019
Ecological Indicators 99 (2019). - ISSN 1470-160X - p. 83 - 90.
Distribution - Geese - MODIS - Nutrient biomass - Plant phenology - Yangtze River floodplain

The distribution of food resources is a key factor in habitat selection. Herbivorous waterfowl prefer early-stage growing plants (from the onset of plant growth to the peak in nutrient biomass) as these offer higher energy intake rates. This plant development stage is not fully captured by commonly used satellite-derived vegetation indicators, which focus on plant biomass (e.g., Enhanced Vegetation Index, EVI) or active plant growth (e.g., the differential EVI between current and a previous date, diffEVI). To improve mapping suitable grazing areas for herbivorous waterfowl, we propose a new satellite-based plant growth indicator of early-stage plant growth (ESPG). We hypothesize that herbivorous waterfowl prefer plants at an early development stage during the growing season and select plants with a relatively later end of ESPG during the non-growing season. We use satellite tracking data of 20 greater white-fronted geese (Anser albifrons) wintering in the Yangtze River floodplain to validate our predictions. We build generalized linear models for goose distributions during the growing and non-growing seasons and compare the performance of ESPG to commonly used plant growth indictors (EVI and diffEVI). During the growing season, ESPG can explain 53% of variation in the goose distribution, outperforming EVI (27%) and diffEVI (34%). During the non-growing season, only the end of ESPG significantly influences goose distribution, explaining 25% of the variance (ESPG: AUC = 0.78; EVI: AUC = 0.58; diffEVI: AUC = 0.58). The newly-developed plant growth indicator ESPG could be used to improve models of herbivorous waterfowl distributions and hence support efforts toward waterfowl conservation and wetland management.

Mass spectrometric characterisation of avenanthramides and enhancing their production by germination of oat (Avena sativa)
Bruijn, Wouter J.C. de; Dinteren, Sarah van; Gruppen, Harry ; Vincken, Jean Paul - \ 2019
Food Chemistry 277 (2019). - ISSN 0308-8146 - p. 682 - 690.
Avena sativa - Avenanthramides - Cereal grain - Germination - LC-MS - Phytoalexin - Plant defence - Poaceae

Avenanthramides are amides, with a phenylalkenoic acid (PA) and an anthranilic acid (AA) subunit, which are secondary metabolites of oat. Oat seeds were germinated, extracted, and the avenanthramides analysed by a combination of UHPLC with ion trap and high resolution ESI-MS. Typical fragmentation pathways with corresponding diagnostic fragments belonging to the PA and AA subunits were identified and summarised in a decision guideline. Based on these findings 28 unique avenanthramides were annotated in the oat seed(ling) extracts, including the new avenanthramide 6f (with a 4/5-methoxy AA subunit). Avenanthramide content increased by 25 times from seed to seedling. Avenanthramides 2p, 2c, and 2f, which are commonly described as the major avenanthramides, represented less than 20% of the total content in the seedlings. Future quantitative analyses should, therefore, include a wider range of avenanthramides to avoid underestimation of the total avenanthramide content.

Revealing microbial processes and nutrient limitation in soil through ecoenzymatic stoichiometry and glomalin-related soil proteins in a retreating glacier forefield
Jiang, Yonglei ; Lei, Yanbao ; Qin, Wei ; Korpelainen, Helena ; Li, Chunyang - \ 2019
Geoderma 338 (2019). - ISSN 0016-7061 - p. 313 - 324.
Bacterial and fungal community structure - Glomalin-related soil protein - Hailuogou Glacier Chronosequence - Soil extracellular enzymes

The glacial retreat is observed and predicted to increase in intensity especially in high-elevation areas as a result of global warming, which leaves behind a primary succession along soil chronosequences. Although soil microbes have been recognized as main drivers of ecological and evolutionary processes, our understanding of their effects on nutrient biogeochemistry during primary succession remains limited. In this study, we investigated changes in the microbial community structure, ecoenzymatic stoichiometry, and glomalin-related soil protein (GRSP) accumulation in the Hailuogou Glacier Chronosequence, located on the eastern Tibetan Plateau. We wanted to reveal the effects of nutrient limitation on soil microbes and the relative contributions of edaphic and biotic factors. The results showed that with an increasing soil age, there was a steady increase in the microbial biomass and a shift from a bacterial to fungal dominated pattern. Soil enzyme stoichiometry and analyses on threshold elemental ratios revealed that microbial activities are limited by carbon and nitrogen during the early successional stage (3–52 years), while phosphorus was the main limiting factor during later stages (80–120 years). Moreover, the redundancy analysis and structural equation modeling suggested that during early stages edaphic factors had a greater impact on microbial processes, while the vegetation factors were most influential during the last two stages. Overall, these results highlighted the importance of integrating knowledge of the microbial community structure, soil enzyme activities and GRSP to gain a holistic view of soil-plant-microbe interactions during ecosystem successions.

An affordable and reliable assessment of aquatic decomposition : Tailoring the Tea Bag Index to surface waters
Seelen, Laura M.S. ; Flaim, Giovanna ; Keuskamp, Joost ; Teurlincx, Sven ; Arias Font, Raquel ; Tolunay, Duygu ; Fránková, Markéta ; Šumberová, Kateřina ; Temponeras, Maria ; Lenhardt, Mirjana ; Jennings, Eleanor ; Senerpont Domis, Lisette N. de - \ 2019
Water Research 151 (2019). - ISSN 0043-1354 - p. 31 - 43.
Carbon cycle - Citizen science - Decomposition constant - European lakes - Lake management - Standardized ecological assay

Litter decomposition is a vital part of the global carbon cycle as it determines not only the amount of carbon to be sequestered, but also how fast carbon re-enters the cycle. Freshwater systems play an active role in the carbon cycle as it receives, and decomposes, terrestrial litter material alongside decomposing aquatic plant litter. Decomposition of organic matter in the aquatic environment is directly controlled by water temperature and nutrient availability, which are continuously affected by global change. We adapted the Tea Bag Index (TBI), a highly standardized methodology for determining soil decomposition, for lakes by incorporating a leaching factor. By placing Lipton pyramid tea bags in the aquatic environment for 3 h, we quantified the period of intense leaching which usually takes place prior to litter (tea) decomposition. Standard TBI methodology was followed after this step to determine how fast decomposition takes place (decomposition rate, k1) and how much of the material cannot be broken down and is thus sequestered (stabilization factor, S). A Citizen Science project was organized to test the aquatic TBI in 40 European lakes located in four climate zones, ranging from oligotrophic to hypereutrophic systems. We expected that warmer and/or eutrophic lakes would have a higher decomposition rate and a more efficient microbial community resulting in less tea material to be sequestered. The overall high decomposition rates (k1) found confirm the active role lakes play in the global carbon cycle. Across climate regions the lakes in the warmer temperate zone displayed a higher decomposition rate (k1) compared to the colder lakes in the continental and polar zones. Across trophic states, decomposition rates were higher in eutrophic lakes compared to oligotrophic lakes. Additionally, the eutrophic lakes showed a higher stabilization (S), thus a less efficient microbial community, compared to the oligotrophic lakes, although the variation within this group was high. Our results clearly show that the TBI can be used to adequately assess the decomposition process in aquatic systems. Using “alien standard litter” such as tea provides a powerful way to compare decomposition across climates, trophic states and ecosystems. By providing standardized protocols, a website, as well as face to face meetings, we also showed that collecting scientifically relevant data can go hand in hand with increasing scientific and environmental literacy in participants. Gathering process-based information about lake ecosystems gives managers the best tools to anticipate and react to future global change. Furthermore, combining this process-based information with citizen science, thus outreach, is in complete agreement with the Water Framework Directive goals as set in 2010.

Phenotypic plasticity as a clue for invasion success of the submerged aquatic plant Elodea nuttallii
Szabó, S. ; Peeters, E.T.H.M. ; Várbíró, G. ; Borics, G. ; Lukács, B.A. - \ 2019
Plant Biology 21 (2019)1. - ISSN 1435-8603 - p. 54 - 63.
Alien - aquatic plant - competition - light - macrophyte - nitrogen

Two closely related alien submerged aquatic plants were introduced into Europe. The new invader (Elodea nuttallii) gradually displaced E. canadensis even at sites where the latter was well established. The aim of the study was to evaluate the combined effects of environmental factors on several phenotypic characteristics of the two Elodea species, and to relate these phenotypic characteristics to the invasion success of E. nuttallii over E. canadensis. In a factorial design, Elodea plants were grown in aquaria containing five different nitrogen concentrations and incubated at five different light intensities. We used six functional traits (apical shoot RGR), total shoot RGR, relative elongation, root length, lateral spread, branching degree) to measure the environmental response of the species. We calculated plasticity indices to express the phenotypic differences between species. Light and nitrogen jointly triggered the development of phenotypic characteristics that make E. nuttallii a more successful invader in eutrophic waters than E. canadensis. The stronger invader showed a wider range of phenotypic plasticity. The apical elongation was the main difference between the two species, with E. nuttallii being more than two times longer than E. canadensis. E. canadensis formed dense side shoots even under high shade and low nitrogen levels, whereas E. nuttallii required higher light and nitrogen levels. We found that under more eutrophic conditions, E. nuttallii reach the water surface sooner than E. canadensis and through intensive branching outcompetes all other plants including E. canadensis. Our findings support the theory that more successful invaders have wider phenotypic plasticity.

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