Wim van Ieperen - Academia.edu (original) (raw)

Papers by Wim van Ieperen

Frontiers in Plant Science

In vertical farming, plants are grown in multi-layered growth chambers supplied with energy-effic... more In vertical farming, plants are grown in multi-layered growth chambers supplied with energy-efficient LEDs that produce less heat and can thus be placed in close proximity to the plants. The spectral quality control allowed by LED lighting potentially enables steering plant development toward desired phenotypes. However, this requires detailed knowledge on how light quality affects different developmental processes per plant species or even cultivar, and how well information from model plants translates to horticultural crops. Here we have grown the model dicotArabidopsis thaliana(Arabidopsis) and the crop plantSolanum lycopersicum(tomato) under white or monochromatic red or blue LED conditions. In addition, seedlings were grownin vitroin either light-grown roots (LGR) or dark-grown roots (DGR) LED conditions. Our results present an overview of phenotypic traits that are sensitive to red or blue light, which may be used as a basis for application by tomato nurseries. Our comparative...

African Journal of Biotechnology, Dec 20, 2010

The Zinnia elegans cell suspension culture is excellent for xylogenesis studies at the cellular a... more The Zinnia elegans cell suspension culture is excellent for xylogenesis studies at the cellular and molecular level, due to the high and synchronous in vitro differentiation of tracheary elements (TEs). The percentage TE differentiation (%TE) in the culture is, however, influenced by a number of factors before and during cell differentiation. One of the factors that is potentially important but has not gotten much attention is the initial osmolarity of the plant material. To examine whether the growth conditions that determine leaf osmolarity (LO) affect the final %TE, we used three light intensities (50, 70 and 100 µmol.m-2 s-1) and three electrical conductivity (EC) levels (EC 2, 4 and 6 dS.m-1) in hydroponic systems to induce different osmolarities in leaf materials from two cultivars (cvs) of Z. elegans, Envy and Purple Prince. The isolated leaf mesophyll cells were subsequently cultured in a liquid medium (300 mOsm extracellular osmolarity) containing-naphthalene acetic acid (NAA) (1 mg.l-1) and benzylaminopurine (BA) (1 mg.l-1). The LO increased in both Zinnia cvs with increasing light intensity and increasing EC during growth. Mesophyll cell size correlated negatively with EC, but the correlation was positive with light intensity in both Zinnia cvs. There was an overall positive correlation between %TE and LO although the degree of %TE change versus LO differed between light and EC treatments and also between the two Zinnia cvs. Envy cv is the best known Z. elegans cv for establishing xylogenic cultures. However, it turned out that by subjecting the plants to different growth conditions, the Purple Prince cv produces a higher %TE as compared to the Envy cv. At EC4 the TE differentiation for the Purple Prince cv was 75%, a level that is 25 to 60% higher than those earlier reported. We conclude that light intensity and EC of the root environment affect the LO of Z. elegans which in turn influences the development and therefore dimensions of TEs in an in vitro xylogenic culture. Thus, proper optimization of the growth conditions for the Zinnia plants prior to establishment of xylogenic cultures leads to enhancement of in vitro TE formation.

Arabidopsis has five phytochrome (PHY) genes for sensing the Red:Far Red (R:FR) ratio in ambient ... more Arabidopsis has five phytochrome (PHY) genes for sensing the Red:Far Red (R:FR) ratio in ambient light, of which PHYA has an established role in responses to FR. To study whether and how PHYs may influence each other’s transcription, PHY-Luciferase reporter plants (pPHYA:LUC, pPHYB:LUC, pPHYC:LUC, pPHYD:LUC and pPHYE:LUC) were constructed. Subsequently, reporter lines representative for each PHY were crossed into each of the five single phy-mutant backgrounds. Reporter activities in WT and phy mutant was studied under diurnal mixed (R, B, FR), R, FR or B LED light in seedling or rosette plants. Both pPHYA:LUC and pPHYB:LUC show strong induction under FR. Full FR upregulation of both PHYA and PHYB is dependent on PHYE, identifying PHYE as a novel sensor for FR light responses. Results also show that PHYA expression is strongly suppressed by PHYD. Results were confirmed for expression of endogenous PHYA and PHYB, albeit with different dynamics compared to the LUC reporters. Profiling ...

Studies on plant-pathogen interactions often involve monitoring disease symptoms or responses of ... more Studies on plant-pathogen interactions often involve monitoring disease symptoms or responses of the host plant to pathogen-derived immunogenic patterns, either visually or by staining the plant tissue. Both these methods have limitations with respect to resolution, reproducibility and the ability to quantify the results. In this study we show that red light detection in a multi-purpose fluorescence imaging system that is probably available in many labs can be used to visualize plant tissue undergoing cell death. Red light emission is the result of chlorophyll fluorescence upon thylakoid membrane disassembly during the development of a programmed cell death process. The activation of programmed cell death can occur either during a hypersensitive response to a biotrophic pathogen or an apoptotic cell death triggered by a necrotrophic pathogen. Quantifying the intensity of the red light signal enables to evaluate the magnitude of programmed cell death and provides a non-invasive reado...

Agricultural Systems, 2020

Wheat yield potentials under rainfed Mediterranean conditions have been long limited by late-in-s... more Wheat yield potentials under rainfed Mediterranean conditions have been long limited by late-in-season occurrence of enhanced water deficits and high temperatures, coinciding with sensitive reproductive stages. Present study aims to quantify and separate the impacts of two main abiotic stresses (drought & heat) on potentially attainable wheat yields, in a typical Mediterranean environment of southern Portugal (Alentejo) over 1986-2015. We also evaluate how possible adaptation options could mitigate potential yield losses (reduce the gap between actual and potential yield). Previously calibrated STICS soil-crop model is used for these purposes, which has been satisfactorily evaluated herein for yield simulations using additional field data before running at regional level. By coupling with high-resolution gridded soil and climate datasets, STICS simulations reliably reproduce the inter-annual variability of 30-year regional yield statistics, together with reasonable estimations of experimental potential yields. Therefore, the model is useful to explore the source of yield gap in the region. The quantified impacts, though with some uncertainties, identify the prolonged terminal drought stress as the major cause of yield gap, causing 40-70% mean potential yield losses. In contrast, a short-duration of crop heat stress (≥38°C) during late grain-filling phase only results in small-to-moderate reductions (up to 20%). Supplemental Irrigation (SI) during reproductive stages provides good adaptive gains to recover potential yield losses by 15-30%, while the proposed early-flowering cultivar is more useful in escaping the terminal heat stress (5-15% adaptive gains) than avoiding prolonged drought stress. In addition, advancing sowing date generally favours wheat production with a robust spatial-temporal pattern. Therefore, combined options based on application of SI, using balanced early-flowering cultivar and early sowing date, may contribute to considerably reduce local yield gap, where current yields can account for 60% of potential yields (26-32% without adaptation). Regional impact assessment and adaptation modelling studies are essential to support agricultural policy development under climate change and variability. The recommended combined adaptation may also represent a promising adaptation strategy for rainfed wheat cropping system in other regions with similar Mediterranean conditions. However, the existing spatial-temporal variability of adaptation response highlights the need to address adaptation strategies at a more detailed local scale with better flexible design.

Climatic Change, 2019

Projected warming and drying trends over the Mediterranean region represent a substantial threat ... more Projected warming and drying trends over the Mediterranean region represent a substantial threat for wheat production. The present study assesses winter wheat yield response to potential climate change and estimates the quantitative effectiveness of using early flowering cultivars and early sowing dates as adaptation options for the major wheat production region of Portugal. A crop model (STICS) is used for this purpose, which is calibrated for yield simulations before projecting future yields. Climate projections over 2021-2050 and 2051-2080 under two emission scenarios (RCP4.5 and RCP8.5) are retrieved from bias-adjusted datasets, generated by a ten-member climate model ensemble. Projected intensification of water deficits and more frequent hightemperature events during late spring (April-June), coinciding with the sensitive grain filling stage, primarily result in continuous mean yield losses (relative to 1981-2010) by − 14% (both scenarios) during 2021-2050 and by − 17% (RCP4.5) or − 27% (RCP8.5) during 2051-2080, also accompanied by increased yield variabilities. Of evaluated adaptation options at various levels, using earlier flowering cultivars reveals higher yield gains (26-38%) than that of early sowings (6-10%), which are able to reverse the yield reductions. The adopted early flowering cultivars successfully advance the anthesis onset and grain filling period, which reduces or avoids the risks of exposure to enhanced drought and heat stresses in late spring. In contrast, winter warming during early sowing window could affect vernalization fulfillment by slowing effective chilling accumulation, thus increasing the pre-anthesis growth length with limited effects on advancing reproductive stage. Crop yield projections and explored adaptation options are essential

Plant, Cell & Environment, 2016

Many studies investigated temperature effects on leaf initiation and expansion by relating these ... more Many studies investigated temperature effects on leaf initiation and expansion by relating these processes to air temperature or the temperature of a specific organ (e.g. leaf temperature). In reality plant temperature is hardly ever equal to air temperature or spatially uniform. Apical bud temperature (T bud), for example, may greatly differ from the temperature of the rest of the plant (T plant) dependent on the environment. Recent research in Cucumis sativus showed that T bud influences leaf initiation independent of T plant. These findings trigger the question if such spatial temperature differences also influence leaf expansion and plant phenotype. In a 28-days study, we maintained temperature differences between T bud and T plant ranging from-7 to +8 o C using a custom-made bud temperature control system. Leaf expansion did not only depend on leaf temperature but also on the difference between bud and leaf temperature. Differences between T bud and T plant considerably influenced vertical leaf area distribution over the shoot: increasing T bud beyond T plant resulted in more and smaller leaves, while decreasing T bud below T plant resulted in less and larger leaves. The trade-off between leaf number and leaf area resulted in phenotypic alterations that cannot be predicted, e.g. by crop models, when assuming plant temperature uniformity.

The Journal of Horticultural Science and Biotechnology, 2009

ABSTRACT Water transport in vascular plants depends on the hydraulic conductance of the xylem sys... more ABSTRACT Water transport in vascular plants depends on the hydraulic conductance of the xylem system, which is dependent on the anatomical properties, number, diameter, and length of the xylem vessels. The ability to transport water through their stems influences not only the growth of many horticultural crops, but also the post-harvest quality of cut flowers. In this study, we investigated the effects of different average daily temperatures (ADT) and the difference between day-time (DT) and night-time (NT) temperature (DIF) on stem size, the length of xylem vessels within the stem, and the length of individual vessel elements within a vessel, in Zinnia elegans. Two Z. elegans cultivars, ‘Envy’ and ‘Purple Prince’, were grown in climate chambers under all nine combinations of three DT and three NT temperatures (viz. 17ºC, 21ºC, or 25ºC). An increase in ADT was positively correlated with the lengths of the stems, internodes, and xylem vessels in both cultivars. However, the lengths of the xylem vessels were influenced more strongly than the lengths of the stems. Increasing the ADT from 17ºC to 25ºC increased stem lengths by approx. 15%, but more than doubled the lengths of the xylem vessels. The increase in xylem vessel lengths was only partly (< 10%) due to an increase in the lengths of individual vessel members, which implies that temperature (ADT) had a greater influence on the number of fused vessel elements per xylem vessel. A negative DIF (i.e., lower DT than NT temperatures) decreased stem lengths and a positive DIF increased stem lengths. DIF had no effect on xylem vessel length, probably because, other than in stem length, xylem vessel length was positively correlated with NT temperature.

The Journal of Horticultural Science and Biotechnology, 2011

In dense crop stands, the decrease in leaf photosynthetic capacity (Amax) is paralleled by a decr... more In dense crop stands, the decrease in leaf photosynthetic capacity (Amax) is paralleled by a decrease in photosynthetically active photon flux density (PPFD) and an increase in leaf age. In greenhouse horticulture, assimilation lighting is traditionally applied from above ...

Acta Horticulturae, 2005

In cut flowers, hydraulic properties and dimensions of xylem vessels in the stem directly influen... more In cut flowers, hydraulic properties and dimensions of xylem vessels in the stem directly influence vase-life and thus post-harvest quality. Xylem hydraulic conductance as well as recovery from air embolisms at the start of vase life strongly depends on number, diameter and length of xylem vessels in the base of the cut flower stems. In this research we employed different water availability levels (high and low water content) in the growing medium of Zinnia elegans plants of three cultivars ('Envy', 'Purple Prince' and 'Scarlet Flame') to modify xylem anatomy and post-harvest xylem functioning and vase life of cut flowers from these plants. Vaselife was longer among fresh-cut Zinnia flowers in all three cultivars grown under low water content in the root medium. Zinnia flowers of all cultivars grown at high water content were not able to sufficiently restore water uptake at the start of their vase life. Shoot hydraulic conductivity was lower in water-stressed plants but it was not different among the three Zinnia cultivars within the same treatment. Anatomical analysis showed smaller xylem vessel diameters but no differences in xylem number and length, with the exception that in cultivar Purple Prince vessels were longer in well-watered plants. We conclude from these results that within these three Zinnia elegans cultivars water stress conditions in the root environment significantly affected xylem anatomy and functioning which correlates well with a longer vase life. Differences in xylem properties between the three cultivars due to pre-harvest watering treatments were limited.

Current Research in Photosynthesis, 1990

The relation between the quantum yield of electron flow in open PS2 reaction centers (Φp) and non... more The relation between the quantum yield of electron flow in open PS2 reaction centers (Φp) and non-photochemical quenching (qNP) during steady state photosynthesis has been shown to be linear (1). Two qantum yield parameters ΦPO and ΦPE were proposed: the quantum yield of electron flow in open PS2 reaction centers in the non-energized and in the energized state respectively. ΦPO and ΦPE were determined by linear extrapolation of ΦP to qNP=0 and qNP=l respectively (1).

Acta Horticulturae, 2012

Breeding for a certain trait is only possible when the phenotypic variation that is caused by gen... more Breeding for a certain trait is only possible when the phenotypic variation that is caused by genotypic variation can be estimated. For traits that strongly depend on environmental conditions, this can be extremely difficult and knowledge and collaboration with experts from other disciplines becomes essential. A wellknown example is breeding for disease resistance. Here, we describe a similar approach to assist breeding against adverse leaf deformations that severely reduce the ornamental value of some chrysanthemum (Dendranthema × grandiflora) genotypes during greenhouse cultivation in winter. These leaf deformations occur rather unpredictably, but seem to be related to the increased use of assimilation light. To breed against this trait knowledge is needed (i) about inductive environments in which sensitive and insensitive genotypes are distinguishable, and (ii) about the physiological background associated with leaf epinasty. In this paper hypothetical physiological factors and mechanisms are discussed, which may mediate effects of light spectrum and greenhouse climate on leaf epinasty. One factor involved could be starch accumulation, since leaf epinasty usually aggravates after disbudding-a practice that most probably alters the sink-source balance. Additionally, light spectra can affect the circadian clock and thereby disturb starch synthesis and breakdown resulting in accumulation. Both within and independent of this process, plant hormones such as auxin and ethylene may play a role in leaf epinasty. This theoretical framework will be used to further investigate the physiological background of leaf epinasty and to come up with a test in which susceptibility for leaf epinasty can be assessed.

Environmental and Experimental Botany, 2016

ABSTRACT The effect of LEDs was studied to induce flower under artificial long days (LD) in Chrys... more ABSTRACT The effect of LEDs was studied to induce flower under artificial long days (LD) in Chrysanthemum morifolium cv. Zembla plants, using light emitting diodes (LED) @ PAR m-2 s-1 80% Red / 20% Blue maintained @ 100 µ mol m- 2 s- 1 using royal blue light @ 455 nm and red light @ 640 nm wavelengths and compared with short day (SD) length. Difference in growth and flowering response were also investigated. Stem length is determined as a function of internode length which could be the function of attaining minimum number of leaves required for expressing the diurnal response using LEDs. Chrysanthemum plants exhibited a strong diurnal response attained in leaves and transmitted to the apex and took minimum (28 days) and maximum time (61 days) with an exposure to LEDs with (15h) and without (11h) additional blue spectrum, respectively. However, bud induction was possible earliest due to low red/far ratio in the extended exposure of plants with blue LEDs.

Janick/Horticultural Reviews, Volume 30, 2010

Nature Communications, 2014

An important constraint for plant biomass production is the natural day length. Artificial light ... more An important constraint for plant biomass production is the natural day length. Artificial light allows for longer photoperiods, but tomato plants develop a detrimental leaf injury when grown under continuous light-a still poorly understood phenomenon discovered in the 1920s. Here, we report a dominant locus on chromosome 7 of wild tomato species that confers continuous light tolerance. Genetic evidence, RNAseq data, silencing experiments and sequence analysis all point to the type III light harvesting chlorophyll a/b binding protein 13 (CAB-13) gene as a major factor responsible for the tolerance. In Arabidopsis thaliana, this protein is thought to have a regulatory role balancing light harvesting by photosystems I and II. Introgressing the tolerance into modern tomato hybrid lines, results in up to 20% yield increase, showing that limitations for crop productivity, caused by the adaptation of plants to the terrestrial 24-h day/night cycle, can be overcome.

Trends in Plant Science, 2007

The Plant Cell, 2012

The mechanisms underlying the wavelength dependence of the quantum yield for CO 2 fixation (a) an... more The mechanisms underlying the wavelength dependence of the quantum yield for CO 2 fixation (a) and its acclimation to the growth-light spectrum are quantitatively addressed, combining in vivo physiological and in vitro molecular methods. Cucumber (Cucumis sativus) was grown under an artificial sunlight spectrum, shade light spectrum, and blue light, and the quantum yield for photosystem I (PSI) and photosystem II (PSII) electron transport and a were simultaneously measured in vivo at 20 different wavelengths. The wavelength dependence of the photosystem excitation balance was calculated from both these in vivo data and in vitro from the photosystem composition and spectroscopic properties. Measuring wavelengths overexciting PSI produced a higher a for leaves grown under the shade light spectrum (i.e., PSI light), whereas wavelengths overexciting PSII produced a higher a for the sun and blue leaves. The shade spectrum produced the lowest PSI:PSII ratio. The photosystem excitation balance calculated from both in vivo and in vitro data was substantially similar and was shown to determine a at those wavelengths where absorption by carotenoids and nonphotosynthetic pigments is insignificant (i.e., >580 nm). We show quantitatively that leaves acclimate their photosystem composition to their growth light spectrum and how this changes the wavelength dependence of the photosystem excitation balance and quantum yield for CO 2 fixation. This also proves that combining different wavelengths can enhance quantum yields substantially.

Scientia Horticulturae, 2011

... Furthermore, a few data are available on species with different pigment composition of the le... more ... Furthermore, a few data are available on species with different pigment composition of the leaves in the young and mature developmental stages ( [Burger and Edwards, 1996] and [Dodd et al., 1998] ) and a part of the experiments have been carried out on cut leaves (or ...