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.

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Optimized sowing time windows mitigate climate risks for oats production under cool semi-arid growing conditions
Zhang, Yue ; Zhang, Lizhen ; Yang, Ning ; Huth, Neil ; Wang, Enli ; Werf, Wopke van der; Evers, Jochem B. ; Wang, Qi ; Zhang, Dongsheng ; Wang, Ruonan ; Gao, Hui ; Anten, Niels P.R. - \ 2019
Agricultural and Forest Meteorology 266-267 (2019). - ISSN 0168-1923 - p. 184 - 197.
APSIM-Oats - Climate change - Cumulative probability - Optimal sowing time window - Water limited potential yield - Yield gap

Year to year variability in weather poses serious risks to crop production in the environmentally fragile agro-ecosystems of cool semi-arid areas, and future climate changes might further aggravate those risks. This study aims to quantify the contribution of altered sowing time windows to reduce climate risk for the production of oats (Avena sativa), a crop that is well adapted to short growing seasons and low rainfall. The APSIM-Oats model was calibrated and validated for phenology, above-ground dry matter and yield using data from field experiments with five sowing dates, conducted from 2009 to 2013 in Inner Mongolia, China. The model was used to determine yield trends and yield-limiting factors under rain-fed conditions using historical weather data. Changes in temperature had greater impact on crop production than changes in rainfall and the simulations indicated the importance of changed sowing windows to lengthen the growth duration and optimize water use. Delayed sowing of oats, 10 days later than current practice, ensured more secure temperature and rainfall conditions from emergence to flowering and substantially increased yields and decreased climate risk. Delayed sowing also reduced climate risk under two future climate scenarios, RCP4.5 (stabilize growth) and RCP8.5 (high greenhouse gas emission). We conclude that adaptation of sowing time of oats provides a practical strategy for enhancing yield and mitigating climate risk under climate change.

Changes of structural and physical properties of semi-gel from Alaska pollock surimi during 4 °C storage
Liu, Xiangyu ; Zhang, Tao ; Xue, Yong ; Xue, Changhu - \ 2019
Food Hydrocolloids 87 (2019). - ISSN 0268-005X - p. 772 - 782.
Cold semi-gelation - Gelation differences - Heat-induced gelation - Surimi gels

This study compared the semi-gel system of Alaska pollock surimi formed at a low temperature with a heat-induced gel system. The cold semi-gel and heat-induced gel were found to have obvious differences in their degrees of protein unfolding, aggregation, and gel network structures. Microscopic observations and an analysis of their fractal dimensions revealed different degrees of compactness and uniformity in the two network structures. Rheological parameters, including the least permanent deformation, equilibrium stress, and frequency exponent, confirmed the non-total aggregation and lower degree of cross-linking in the cold semi-gel. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that the myosin heavy chain (MHC) value gradually decreased, but the light meromyosin (LMM) value remained stable during cold storage. Furthermore, a decrease in the α-helix and an increase in the β-sheet and random coil values, as revealed by Fourier-transform infrared (FT-IR) spectroscopy, indicated that the proteins unfolded differently in the two gel systems. By comparing the times required for the cold semi-gel and heat-induced gel to form, we concluded that the formation process of heat-induced gel is intertwined while it is temporally separated in cold storage. Overall, myosin was selected as the starting point for establishing a schema chart to characterize the gelation processes of the cold semi-gel and heat-induced gel. These findings are helpful for understanding the gelation process of surimi in refrigerated storage.

Effects of pre-emulsification by three food-grade emulsifiers on the properties of emulsified surimi sausage
Liu, Xiangyu ; Ji, Lei ; Zhang, Tao ; Xue, Yong ; Xue, Changhu - \ 2019
Journal of Food Engineering 247 (2019). - ISSN 0260-8774 - p. 30 - 37.
Emulsification process - Emulsified surimi sausage - Peanut oil - Textural properties

In this study, we investigated the effects of peanut oil pre-emulsification by three food-grade emulsifiers (soy protein isolate (SPI), konjac glucomannan (KGM), and acetylated distarch phosphate (ADSP)) on the properties of emulsified surimi sausage. TPA tests showed that KGM comprehensively improved sausage texture. SPI reduced the emulsified sausage hardness from 131.37 ± 3.12 N to 111.13 ± 1.23 N and ADSP reduced the adhesiveness of the product from −0.57 ± 0.05 to −0.37 ± 0.04. The water holding capacity, emulsification stability, and whiteness properties improved significantly after adding the pre-emulsified peanut oil (p < 0.05). Rheology experiments and particle size measurements revealed competitive emulsification between myosin and each emulsifier. Finally, more uniform distributions of oil droplets in the SPI, KGM, and ADSP groups were observed by optical microscopy. Overall, KGM is suggested as the ideal candidate for the pre-emulsification of peanut oil for emulsified surimi sausage products.

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.

Assessing the impact of human interventions on floods and low flows in the Wei River Basin in China using the LISFLOOD model
Gai, Lingtong ; Nunes, João P. ; Baartman, Jantiene E.M. ; Zhang, Hongming ; Wang, Fei ; Roo, Ad de; Ritsema, Coen J. ; Geissen, Violette - \ 2019
Science of the Total Environment 653 (2019). - ISSN 0048-9697 - p. 1077 - 1094.
Flood return period - Hydrological model - Land use - LISFLOOD - Reservoir - Water diversion

Floods are extreme hydroclimatic events that threaten societies and ecosystems. The effects of these events are greatly influenced by the changes that humans have imposed on the environment. The LISFLOOD model is a physically based rainfall-runoff model that simulates the hydrological processes in a catchment. Using globally available land cover, soil, and vegetation as well as meteorological and geographical datasets as input, the LISFLOOD model has the potential to be applied worldwide, even for regions where data are lacking. This study first calibrated and validated the LISFLOOD model in the Wei River Basin in China (432,000 km2) for the years between 2000 and 2010 at 0.05° resolution with a monthly Nash-Sutcliffe model efficiency coefficient of 0.79 at the Huaxian station located at the catchment outlet. The outlets of 17 tributaries draining into the main river were then identified in order to assess the contribution of each tributary to the total runoff occurring as a result of flooding. Four categories of scenarios focusing on human interventions in the basin were created and evaluated: 1) Business as usual, 2) Additional reservoirs constructed in different catchments, 3) Land use as in 1980, and 4) Water diversion plan with a pipeline injection of a fixed daily inflow from an adjacent catchment. The results of the scenarios are presented for three strategically important cities located on the floodplain. In general, the construction of the reservoirs could have an effect on reducing peak flows and decreasing the flood return periods while increasing the low flows. The water diversion plan scenarios increased the low flow by 41 times averaged for the three cities. In conclusion, the LISFLOOD model is a sophisticated model for land and water management planning on the catchment scale for reducing the effects of flood and drought.

Conflation of expert and crowd reference data to validate global binary thematic maps
Waldner, François ; Schucknecht, Anne ; Lesiv, Myroslava ; Gallego, Javier ; See, Linda ; Pérez-Hoyos, Ana ; andrimont, Raphaël D'; Maet, Thomas De; Bayas, Juan Carlos Laso ; Fritz, Steffen ; Leo, Olivier ; Kerdiles, Hervé ; Díez, Mónica ; Tricht, Kristof Van; Gilliams, Sven ; Shelestov, Andrii ; Lavreniuk, Mykola ; Simões, Margareth ; Ferraz, Rodrigo ; Bellón, Beatriz ; Bégué, Agnès ; Hazeu, Gerard ; Stonacek, Vaclav ; Kolomaznik, Jan ; Misurec, Jan ; Verón, Santiago R. ; Abelleyra, Diego De; Plotnikov, Dmitry ; Mingyong, Li ; Singha, Mrinal ; Patil, Prashant ; Zhang, Miao ; Defourny, Pierre - \ 2019
Remote Sensing of Environment 221 (2019). - ISSN 0034-4257 - p. 235 - 246.
With the unprecedented availability of satellite data and the rise of global binary maps, the collection of shared reference data sets should be fostered to allow systematic product benchmarking and validation. Authoritative global reference data are generally collected by experts with regional knowledge through photo-interpretation. During the last decade, crowdsourcing has emerged as an attractive alternative for rapid and relatively cheap data collection, beckoning the increasingly relevant question: can these two data sources be combined to validate thematic maps? In this article, we compared expert and crowd data and assessed their relative agreement for cropland identification, a land cover class often reported as difficult to map. Results indicate that observations from experts and volunteers could be partially conflated provided that several consistency checks are performed. We propose that conflation, i.e., replacement and augmentation of expert observations by crowdsourced observations, should be carried out both at the sampling and data analytics levels. The latter allows to evaluate the reliability of crowdsourced observations and to decide whether they should be conflated or discarded. We demonstrate that the standard deviation of crowdsourced contributions is a simple yet robust indicator of reliability which can effectively inform conflation. Following this criterion, we found that 70% of the expert observations could be crowdsourced with little to no effect on accuracy estimates, allowing a strategic reallocation of the spared expert effort to increase the reliability of the remaining 30% at no additional cost. Finally, we provide a collection of evidence-based recommendations for future hybrid reference data collection campaigns.
Exploring optimal catch crops for reducing nitrate leaching in vegetable greenhouse in North China
Zhang, Hongyuan ; Hu, Kelin ; Zhang, Lijuan ; Ji, Yanzhi ; Qin, Wei - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 273 - 282.
Catch crop - Greenhouse vegetable field - N uptake - Nitrate leaching - Soil-crop system model

Chinese intensive greenhouse vegetable systems are characterized by high input of water and nutrients, which are not sustainable. There is an urgent need to explore smart and practical strategies to convert the “high input-low output” systems to “optimal input-output” ones. This study aimed to evaluate the effects of different catch crops on reducing nitrate leaching in the vegetable greenhouse during the summer fallow season. A two-year field experiment with three catch crops, i.e., sweet corn (SC), amaranth (A) and sweet sorghum (SG), and no catch crop (CK) were conducted in vegetable greenhouse in Dingzhou city, Hebei province, China. The measured soil water content and inorganic nitrogen (N) content in soil profile, biomass and crop N uptake were used to validate the WHCNS (Soil Water Heat Carbon Nitrogen Simulator) model, soil water movement and nitrate leaching were simulated. The results showed that the catch crops decreased the water drainage by 18.2–29.0% and nitrate leaching by 23.3–42.3% respectively, compared with CK. The water drainage reduction ranked as SC > SG > A, while the nitrate leaching reduction was A > SC > SG. The biomass was SC > SG > A, while the crop N uptake was SC > A > SG. Sweet corn could absorb the residual nitrate in the deep soil layers due to the long root system, while amaranth could absorb most residual nitrate in the surface soil. Amaranth showed greater N-uptake capacity than sweet corn, and the nitrate was mainly accumulated in the surface soil. Planting amaranth as summer catch crop reduced nitrate leaching in the vegetable greenhouses. Our study provides a guideline for selecting effective catch crops in intensive vegetable greenhouses in North China.

Self-assembly of ellipsoidal particles at fluid-fluid interfaces with an empirical pair potential
Luo, Alan M. ; Vermant, Jan ; Ilg, Patrick ; Zhang, Zhenkun ; Sagis, Leonard M.C. - \ 2019
Journal of Colloid and Interface Science 534 (2019). - ISSN 0021-9797 - p. 205 - 214.
Capillary interactions - Ellipsoidal particles - Empirical pair potential - Fluid-fluid interfaces - Self-assembly

Colloidal particles adsorbed at fluid-fluid interfaces interact via mechanisms that can be specific to the presence of interfaces, for instance, lateral capillary interactions induced by nonspherical particles. Capillary interactions are highly relevant for self-assembly and the formation of surface microstructures, however, these are very challenging to model due to the multibody nature of capillary interactions. This work pursues a direct comparison between our computational modelling approach and experimental results on surface microstructures formed by ellipsoidal particles. We begin by investigating the accuracy of using pairwise interactions to describe the multibody capillary interaction by contrasting exact two- and three-particle interaction energies and we find that the pairwise approximation appears reasonable for the experimentally relevant configurations studied. We then develop an empirical pair potential and use it in Monte-Carlo type simulations to efficiently model the structure formation process for relevant particle properties such as aspect ratio, contact angle and surface coverage, and succeed in reproducing our experimental observations where we spread sterically-stabilised ellipsoidal particles onto an oil-air interface at high surface coverage. At lower surface coverages, we find that the self-assembly process falls into the diffusion-limited colloid aggregation universality class.

Plastic film cover during the fallow season preceding sowing increases yield and water use efficiency of rain-fed spring maize in a semi-arid climate
Zhang, Zhe ; Zhang, Yanqing ; Sun, Zhanxiang ; Zheng, Jiaming ; Liu, Enke ; Feng, Liangshan ; Feng, Chen ; Si, Pengfei ; Bai, Wei ; Cai, Qian ; Yang, Ning ; Werf, Wopke van der; Zhang, Lizhen - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 203 - 210.
Film cover - Soil temperature - Water availability - Yield components

Plastic film mulch increases crop yields in rain-fed agriculture in cool semi-arid climates by warming the soil and reducing evaporative water losses. The semi-arid Khorchin area in Northeast China is an important production area for rain-fed maize. Drought stress occurs frequently, even if plastic film mulch is applied at sowing. We hypothesized that the yield and water capture of maize could be increased by reducing evaporative loss of water by use of plastic film cover during the autumn and winter preceding sowing. In this study, we compared maize growth, water uptake and yield in three film cover treatments: (1) film cover from the autumn before maize sowing until maize harvest (autumn mulching: AM), (2) film cover from maize sowing till harvest (conventional practice) (spring mulching: SM), (3) no film cover (no mulch: NM). Field experiments were conducted in Fuxin city, Khorchin region, Liaoning province, China in 2013/2014 and 2014/2015. Autumn mulching increased grain yield on average by 18% when compared to spring mulching and by 36% when compared to no mulching. The 1000-kernel weight in AM was 7% higher than in SM, and 12% higher than in NM. Soil water content in the root zone before sowing was 35 mm greater in AM than in SM and NM. Water uptake during the growing season was 34 mm greater in AM than in SM and NM. Water use efficiency for grain yield (yield per unit water uptake) in AM was on average 2.5% higher than in conventional mulching (SM) and 27% higher than in NM. Autumn mulching advanced development, with an advance of 5 days in tasseling time as compared to SM and 10 days when compared to NM. These results show that film cover during the fallow period before maize sowing can increase crop yield and water use efficiency, and reduce climate risks in rain-fed agriculture under semi-arid conditions.

Latitudinal adaptation and genetic insights into the origins of cannabis sativa L.
Zhang, Qingying ; Chen, Xuan ; Guo, Hongyan ; Trindade, Luisa M. ; Salentijn, Elma M.J. ; Guo, Rong ; Guo, Mengbi ; Xu, Yanping ; Yang, Ming - \ 2018
Cannabaceae - CpDNA - Genetic diversity - Industrial hemp - Phylogeography

Cannabis is one of the most important industrial crops distributed worldwide. However, the phylogeographic structure and domestication knowledge of this crop remains poorly understood. In this study, sequence variations of five chloroplast DNA (cpDNA) regions were investigated to address these questions. For the 645 individuals from 52 Cannabis accessions sampled (25 wild populations and 27 domesticated populations or cultivars), three haplogroups (Haplogroup H, M, L) were identified and these lineages exhibited distinct high-middle-low latitudinal gradients distribution pattern. This pattern can most likely be explained as a consequence of climatic heterogeneity and geographical isolation. Therefore, we examined the correlations between genetic distances and geographical distances, and tested whether the climatic factors are correlated with the cpDNA haplogroup frequencies of populations. The “isolation-by-distance” models were detected for the phylogeographic structure, and the day-length was found to be the most important factor (among 20 BioClim factors) that influenced the population structures. Considering the distinctive phylogeographic structures and no reproductive isolation among members of these lineages, we recommend that Cannabis be recognized as a monotypic genus typified by Cannabis sativa L., containing three subspecies: subsp. sativa, subsp. Indica, and subsp. ruderalis. Within each haplogroup which possesses a relatively independent distribution region, the wild and domesticated populations shared the most common haplotypes, indicating that there are multiregional origins for the domesticated crop. Contrast to the prevalent Central-Asia-Origin hypothesis of C. saltiva, molecular evidence reveals for the first time that the low latitude haplogroup (Haplogroup L) is the earliest divergent lineage, implying that Cannabis is probably originated in low latitude region.

Learning deep structure active contours end-to-end
Marcos Gonzalez, D. ; Tuia, D. ; Kellenberger, B.A. ; Zhang, L. ; Bai, M. ; Liao, R. ; Urtasun, R. - \ 2018
- 9 p.
Chinese steamed bread and novel wheat products
Zhang, Zhengmao ; Xing, Qinhui ; Liu, Yuxiu - \ 2018
In: Flour Nova Science Publishers - ISBN 9781536137613 - p. 175 - 184.
Aroma - Chinese steamed bread - Gluten content - Products - Wheat

Wheat is one of the most important agricultural crops globally, and the third-largest food crop after rice and maize in China; in particular, wheat is one of the primary provisions in human diets in Northern China. Research on the quality of wheat flour is important for wheat food production. Steam bread was one of staple foods in the northern part of China due to the combination of unique cultures and dietary habits. The Chinese steamed bread-making process is a complex system. There is significant value in research on the aroma characteristics of wheat flour, fermented dough, and steamed bread. The solid phase micro-extraction (SPME) GC-MS was used to investigate the compounds of volatile aroma in gelatinized-flour. Volatile compounds of steamed bread vary depending on the content of gluten in wheat flour. In the three physical stages of making Chinese steamed bread, the quantity of hydrocarbons and aldehydes first decreased and then increased. Chinese steamed bread made from wheat flour with added 3% of stachyose, has the greatest elasticity and extensibility, and has the highest scores when conducted for sensory evaluation, thus making nutrient fortified steamed bread. Along with the developing and applying of the modern food process technology, wheat also can be made for novel wheat products with different flavors, such as wheat bran, wheat germ flour, wheat germ oil and “popwheat”, and further caramel treats. In addition, volatile compounds of wheat bran and germ differ between high gluten, middle gluten and low gluten flour. Therefore, the research on the processing quality of wheat dough has been a hot topic.

Intercropping potato (Solanum tuberosum L.) with hairy vetch (Vicia villosa) increases water use efficiency in dry conditions
Ren, Jianhong ; Zhang, Lizhen ; Duan, Yu ; Zhang, Jun ; Evers, Jochem B. ; Zhang, Yue ; Su, Zhicheng ; Werf, Wopke van der - \ 2018
Field Crops Research (2018). - ISSN 0378-4290
Biomass - Daily water use - Land equivalent ratio (LER) - Water equivalent ratio (WER) - Water saving

Protection from soil erosion and efficient use of water are vital to sustainable dryland potato production in semi-arid regions. Introducing legumes into semi-arid agricultural systems as intercrops improves soil quality due to biological nitrogen fixation and reduced wind erosion as a result of better soil cover, but the consequences of introducing legumes for the water use efficiency of the crop system are less predictable. Here we carried out field experiments from 2014 to 2017 in Inner Mongolia, China. We compared a rotational intercropping system of potato (Solanum tuberosum L.) and hairy vetch (Vicia villosa) with monocultures of potato and hairy vetch and quantified crop yield, water use efficiency and land productivity. While the relative density (the ratio of plant density in intercrop and the density in sole stand) of both crops in the intercropping was 0.5, the average relative yield of the potato over four years was 0.43, but that of the vetch was 0.87, indicating dominance of the vetch in the intercropping system. Land and water equivalent ratios, defined as the area of land or amount of water that would be needed in single cropping to achieve the same yield as in intercropping, averaged to 1.30 and 1.29 over the years, respectively, indicating high relative land and water productivity of potato/hairy vetch intercropping compared to monocultures. Vetch was a stronger competitor for water than potato with a partial water equivalent ratio of 0.83. We conclude that the potato/vetch intercropping system improves land productivity and system level water use efficiency under the rain-fed semi-arid conditions of the study site. These results are useful to optimize cropping systems for regional sustainability with consideration of both arable crop production (potato) and provision of fodder for animal husbandry (vetch).

Experiments Are Necessary in Process-Based Tree Phenology Modelling
Hänninen, Heikki ; Kramer, Koen ; Tanino, Karen ; Zhang, Rui ; Wu, Jiasheng ; Fu, Yongshuo H. - \ 2018
Trends in Plant Science (2018). - ISSN 1360-1385
bud burst - climate change - dormancy - phenology - process-based modelling

In boreal and temperate trees, air temperature is a major environmental factor regulating the timing of spring phenological events, such as vegetative bud burst, through underlying physiological processes. This has been established by experimental research, and mathematical process-based tree phenology models have been developed based on the results. The models have often been applied when assessing the effects of climate change. Currently, there is an increasing trend to develop process-based tree phenology models using only observational phenological records from natural conditions. We point out that this method runs a high risk of producing models that do not simulate the real physiological processes in the trees and discuss experimental designs facilitating the development of biologically realistic process-based models for tree spring phenology.

Red/blue light ratio strongly affects steady-state photosynthesis, but hardly affects photosynthetic induction in tomato (Solanum lycopersicum)
Zhang, Yuqi ; Kaiser, Elias ; Zhang, Yating ; Yang, Qichang ; Li, Tao - \ 2018
Physiologia Plantarum (2018). - ISSN 0031-9317

Plants are often subjected to rapidly alternating light intensity and quality. While both short- and long-term changes in red and blue light affect leaf photosynthesis, their impact on dynamic photosynthesis is not well documented. It was tested how dynamic and steady-state photosynthetic traits were affected by red/blue ratios, either during growth or during measurements, in tomato leaves. Four red/blue ratios were used: monochromatic red (R100), monochromatic blue (B100), a red/blue light ratio of 9:1 (R90B10) and a red/blue light ratio of 7:3 (R70B30). R100 grown leaves showed decreased photosynthetic capacity (maximum rates of light-saturated photosynthesis, carboxylation, electron transport and triose phosphate use), leaf thickness and nitrogen concentrations. Acclimation to various red/blue ratios had limited effects on photosynthetic induction in dark-adapted leaves. B100-grown leaves had a approximately 15% larger initial NPQ transient than the other treatments, which may be beneficial for photoprotection under fluctuating light. B100-grown leaves also showed faster stomatal closure when exposed to low light intensity, which likely resulted from smaller stomata and higher stomatal density. When measured under different red/blue ratios, stomatal opening rate and photosynthetic induction rate were hardly accelerated by increased fractions of blue light in both growth chamber-grown leaves and greenhouse-grown leaves. However, steady-state photosynthesis rate 30 min after photosynthetic induction was strongly reduced in leaves exposed to B100 during the measurement. We conclude that varying red/blue light ratios during growth and measurement strongly affects steady-state photosynthesis, but has limited effects on photosynthetic induction rate.

Role for Arabidopsis PLC7 in Stomatal Movement, Seed Mucilage Attachment, and Leaf Serration
Wijk, Ringo van; Zhang, Qianqian ; Zarza, Xavier ; Lamers, M. ; Reyes Marquez, F.C. ; Guardia, Aisha ; Scuffi, Denise ; García-Mata, Carlos ; Ligterink, W. ; Haring, M.A. ; Laxalt, A.M. ; Munnik, Teun - \ 2018
Frontiers in Plant Science 9 (2018). - ISSN 1664-462X
Phospholipase C (PLC) has been suggested to play important roles in plant stress and development. To increase our understanding of PLC signaling in plants, we have started to analyze knock-out (KO), knock-down (KD) and overexpression mutants of Arabidopsis thaliana, which contains nine PLCs. Earlier, we characterized PLC2, PLC3 and PLC5. Here, the role of PLC7 is functionally addressed. Promoter-GUS analyses revealed that PLC7 is specifically expressed in the phloem of roots, leaves and flowers, and is also present in trichomes and hydathodes. Two T-DNA insertion mutants were obtained, i.e., plc7-3 being a KO- and plc7-4 a KD line. In contrast to earlier characterized phloem-expressed PLC mutants, i.e., plc3 and plc5, no defects in primary- or lateral root development were found for plc7 mutants. Like plc3 mutants, they were less sensitive to ABA during stomatal closure. Double-knockout plc3 plc7 lines were lethal, but plc5 plc7 (plc5/7) double mutants were viable, and revealed several new phenotypes, not observed earlier in the single mutants. These include a defect in seed mucilage, enhanced leaf serration, and an increased tolerance to drought. Overexpression of PLC7 enhanced drought tolerance too, similar to what was earlier found for PLC3-and PLC5 overexpression. In vivo 32Pi-labeling of seedlings and treatment with sorbitol to mimic drought stress, revealed stronger PIP2 responses in both drought-tolerant plc5/7 and PLC7-OE mutants. Together, these results show novel functions for PLC in plant stress and development. Potential molecular mechanisms are discussed.
POLAR-guided signalling complex assembly and localization drive asymmetric cell division
Houbaert, Anaxi ; Zhang, Cheng ; Tiwari, Manish ; Wang, Kun ; Marcos Serrano, Alberto de; Savatin, Daniel V. ; Urs, Mounashree J. ; Zhiponova, Miroslava K. ; Gudesblat, Gustavo E. ; Vanhoutte, Isabelle ; Eeckhout, Dominique ; Boeren, Sjef ; Karimi, Mansour ; Betti, Camilla ; Jacobs, Thomas ; Fenoll, Carmen ; Mena, Montaña ; Vries, Sacco de; Jaeger, Geert De; Russinova, Eugenia - \ 2018
Nature 563 (2018)7732. - ISSN 0028-0836 - p. 574 - 578.

Stomatal cell lineage is an archetypal example of asymmetric cell division (ACD), which is necessary for plant survival1-4. In Arabidopsis thaliana, the GLYCOGEN SYNTHASE KINASE3 (GSK3)/SHAGGY-like kinase BRASSINOSTEROID INSENSITIVE 2 (BIN2) phosphorylates both the mitogen-activated protein kinase (MAPK) signalling module5,6 and its downstream target, the transcription factor SPEECHLESS (SPCH)7, to promote and restrict ACDs, respectively, in the same stomatal lineage cell. However, the mechanisms that balance these mutually exclusive activities remain unclear. Here we identify the plant-specific protein POLAR as a stomatal lineage scaffold for a subset of GSK3-like kinases that confines them to the cytosol and subsequently transiently polarizes them within the cell, together with BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL), before ACD. As a result, MAPK signalling is attenuated, enabling SPCH to drive ACD in the nucleus. Moreover, POLAR turnover requires phosphorylation on specific residues, mediated by GSK3. Our study reveals a mechanism by which the scaffolding protein POLAR ensures GSK3 substrate specificity, and could serve as a paradigm for understanding regulation of GSK3 in plants.

Hepatic Sel1L-Hrd1 ER-Associated Degradation (ERAD) manages FGF21 levels and systemic metabolism via CREBH
Bhattacharya, Asmita ; Sun, Shengyi ; Wang, Heting ; Liu, Ming ; Long, Qiaoming ; Yin, Lei ; Kersten, A.H. ; Zhang, Kezhong ; Qi, Ling - \ 2018
GSE118658 - PRJNA486359 - Mus musculus
Fibroblast growth factor 21 (Fgf21) is a liver-derived, fasting-induced hormone with broad effects on growth, nutrient metabolism and insulin sensitivity. Here, we report the discovery of a novel mechanism regulating Fgf21 expression under growth and fasting-feeding. The Sel1LHrd1 complex is the most conserved branch of mammalian endoplasmic reticulum (ER)- associated degradation (ERAD) machinery. Mice with liver-specific deletion of Sel1L exhibit growth retardation with markedly elevated circulating Fgf21, reaching levels close to those in Fgf21 transgenic mice or pharmacological models. Mechanistically, we show that the Sel1LHrd1 ERAD complex controls Fgf21 transcription by regulating the ubiquitination and turnover (and thus nuclear abundance) of ER-resident transcription factor Crebh, while having no effect on the other well-known Fgf21 transcription factor Pparα. Our data reveal a physiologically regulated, inverse correlation between Sel1L-Hrd1 ERAD and Crebh-Fgf21 levels under fasting-feeding and growth. This study not only establishes the importance of Sel1L-Hrd1 ERAD in the liver in the regulation of systemic energy metabolism, but also reveals a novel hepatic “ERADCrebh- Fgf21” axis directly linking ER protein turnover to gene transcription and systemic metabolic regulation.
Herbivores avoid host plants previously exposed to their omnivorous predator Macrolophus pygmaeus
Zhang, Nina ; Wieringen, Daan van; Messelink, Gerben J. ; Janssen, Arne - \ 2018
Journal of pest science (2018). - ISSN 1612-4758 - 9 p.
Herbivore host plant selection - Herbivore performance - Induced defence - Macrolophus pygmaeus - Omnivore - Predation risk

Herbivorous arthropods use various cues to choose suitable host plants. We investigated whether three species of herbivores use cues associated with their omnivorous predator Macrolophus pygmaeus to select host plants. Earlier, we found that this omnivore induces plant defences which decreased the performance of two of the herbivores, i.e. the spider mite Tetranychus urticae and the western flower thrips Frankliniella occidentalis, whereas the green peach aphid Myzus persicae was not affected. Hence, the spider mite and thrips were expected to avoid plants that were previously exposed to M. pygmaeus because of their lower quality, and the aphid was not expected to avoid exposed plants because they were of equal quality as unexposed plants. However, the cues left behind by M. pygmaeus may also be indicative of predation risk, in which case all three herbivores were expected to avoid exposed plants. Spider mites and western flower thrips preferred clean plants over plants that had previously been exposed to M. pygmaeus, but no longer harboured this omnivore. Aphids showed no preference, in agreement with their performance, but not in agreement with reducing predation risk. We furthermore showed that the preference of spider mites and thrips for clean plants increased through time. Higher proportions of aphids left plants previously exposed to M. pygmaeus than clean plants through time. Hence, omnivorous predators can decrease herbivore densities on plants not only by killing them but also by indirectly affecting herbivore host plant selection.

Hepatic Sel1L-Hrd1 ER-associated degradation (ERAD) manages FGF21 levels and systemic metabolism via CREBH
Bhattacharya, Asmita ; Sun, Shengyi ; Wang, Heting ; Liu, Ming ; Long, Qiaoming ; Yin, Lei ; Kersten, Sander ; Zhang, Kezhong ; Qi, Ling - \ 2018
The EMBO Journal 37 (2018)22. - ISSN 0261-4189
ER quality control - FGF21 - gene transcription - metabolism - Sel1L-Hrd1 ERAD

Fibroblast growth factor 21 (Fgf21) is a liver-derived, fasting-induced hormone with broad effects on growth, nutrient metabolism, and insulin sensitivity. Here, we report the discovery of a novel mechanism regulating Fgf21 expression under growth and fasting-feeding. The Sel1L-Hrd1 complex is the most conserved branch of mammalian endoplasmic reticulum (ER)-associated degradation (ERAD) machinery. Mice with liver-specific deletion of Sel1L exhibit growth retardation with markedly elevated circulating Fgf21, reaching levels close to those in Fgf21 transgenic mice or pharmacological models. Mechanistically, we show that the Sel1L-Hrd1 ERAD complex controls Fgf21 transcription by regulating the ubiquitination and turnover (and thus nuclear abundance) of ER-resident transcription factor Crebh, while having no effect on the other well-known Fgf21 transcription factor Pparα. Our data reveal a physiologically regulated, inverse correlation between Sel1L-Hrd1 ERAD and Crebh-Fgf21 levels under fasting-feeding and growth. This study not only establishes the importance of Sel1L-Hrd1 ERAD in the liver in the regulation of systemic energy metabolism, but also reveals a novel hepatic “ERAD-Crebh-Fgf21” axis directly linking ER protein turnover to gene transcription and systemic metabolic regulation.

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