Effects of anti-transpirants on transpiration and energy use in greenhouse cultivation

Greenhouse production in North-West Europe consumes a lot of energy. The energy is needed for heating the greenhouse and controlling air humidity. Transpiration of a crop increases the energy use. The aim of this study was to explore the possibilities for the application of anti-transpirants to save energy by reducing crop transpiration without reducing crop yield. Literature and model calculations were used to explore the effects of increased leaf resistances on transpiration, energy use and production in tomato, cucumber and sweet pepper. In literature a large number of compounds are described that act as anti-transpirant. A two to five fold increase in stomatal resistance can be expected from treatment with anti-transpirants. Model calculations for tomato showed that increasing the stomatal resistance (from 2 to 5 times) throughout the whole year leads to substantial yield reduction: crop growth was reduced by 6-19%, while transpiration by 15-42% and consequently energy use by 9-16%. However, in the winter period (beginning of October/end of March) the growth reduction was only 0.3-1.3%, as in this period light levels are low and CO2 concentrations in the greenhouse are relatively high. Raising the (maximum) set-point for CO2 concentration from 1000 ppm to 3000 ppm, increased the actual concentration during day-time from 892 to 1567 ppm (flue gases were the only source of CO2). When the application of anti-transpirants was combined with raising the set-point for CO2 concentration, the model showed no growth reduction due to the application of anti-transpirants, while the annual energy use was reduced by 5.5-10.4% in tomato. Similar results were obtained for sweet pepper (5-9% energy saving) and cucumber (2-5% energy saving). These model calculations show that increasing stomatal resistance by anti-transpirants during the winter period may potentially save a substantial amount of energy (2-10%), without affecting yield of vegetables such as tomato, cucumber and sweet pepper. It is concluded that increasing the stomatal resistance by anti-transpirants in wintertime may lead to substantial energy saving due to the reduced transpiration and need for humidity management, without yield reduction. Such model calculations are useful to analyse beforehand the chances of a good combination of energy saving and yield loss of a possible application. Experiments will be needed to verify the result

How to Measure Molecular Forces in Cells: A Guide to Evaluating Genetically-Encoded FRET-Based Tension Sensors

The ability of cells to sense and respond to mechanical forces is central to a wide range of biological processes and plays an important role in numerous pathol- ogies. The molecular mechanisms underlying cellular mech- anotransduction, however, have remained largely elusive because suitable methods to investigate subcellular force propagation were missing. Here, we review recent advances in the development of biosensors that allow molecular force measurements. We describe the underlying principle of currently available techniques and propose a strategy to systematically evaluate new Fo ̈ rster resonance energy trans- fer (FRET)-based biosensor

Metavinculin modulates force transduction in cell adhesion sites

Vinculin is a ubiquitously expressed protein, crucial for the regulation of force transduction in cells. Muscle cells express a vinculin splice-isoform called metavinculin, which has been associated with cardiomyopathies. However, the molecular function of metavinculin has remained unclear and its role for heart muscle disorders undefined. Here, we have employed a set of piconewton-sensitive tension sensors to probe metavinculin mechanics in cells. Our experiments reveal that metavinculin bears higher molecular forces but is less frequently engaged as compared to vinculin, leading to altered force propagation in cell adhesions. In addition, we have generated knockout mice to investigate the consequences of metavinculin loss in vivo. Unexpectedly, these animals display an unaltered tissue response in a cardiac hypertrophy model. Together, the data reveal that the transduction of cell adhesion forces is modulated by expression of metavinculin, yet its role for heart muscle function seems more subtle than previously thought. Muscle cells express an adhesion molecule called metavinculin, which has been associated with cardiomyopathies. Here, the authors employed molecular tension sensors to reveal that metavinculin expression modulates cell adhesion mechanics and they develop a mouse model to demonstrate that the presence of metavinculin is not as critical for heart muscle function as previously thought

Variability in yield of faba beans (Vicia faba L.)

Yield variability is one of the major problems in growing faba beans. In this thesis, the effect of water supply pattern on yield variability of the crop is studied with experiments in the field and under controlled conditions, and with a simulation model. In a series of field experiments, water shortage during flowering, followed by plenty of water after flowering resulted in 30-200% higher pod retention at early formed nodes, a 7% higher Harvest Index, equal average seed yields (6 t ha -1, 100% d.m.), but a 57% larger seed yield range, compared with plenty of water during and after flowering. In some experiments, mild water shortage during flowering resulted in final seed yields which were significantly higher (0.3-0.6 t ha -1) than with plenty of water both during and after flowering. Water shortage after flowering resulted in yield limitations of more than 3 t ha -1and a 200% larger seed yield range. Crop physiological measurements showed that faba beans have insufficient osmotic adjustment and/or adaptation of cell wall elasticity. Thus, the turgor of young stems and leaves, the expansive growth and the vegetative sink strength decrease already with mild water shortage. The stomatal conductance and photosynthesis decrease only at more severe water shortage. It is argued how this may explain the positive effect of mild water shortage on the dry matter partitioning to reproductive organs. The effects are compared with those found in cotton. In a simulation model the physiological knowledge is implemented and calibrated. The model outcomes correspond with the measured average seed yields and account for up to 80% of the measured yield variation of data sets of several locations in Western Europe. Applying plenty of water after flowering increases the average seed yields with 17%-42% and reduces the standard deviation of the seed yields, a measure for the variability, with 43%-73%. Plenty of water during and after flowering has almost no additional effects. It is shown that the positive effect of mild water shortage during flowering on seed yield has only limited value as a target for crop management. But, plenty of water after flowering is crucial for high and stable seed yields. Model explorations show that a doubling of the rooted depth reduces the seed yield variability with about 30%, but a doubling of the water extraction capacity of the crop does not reduce the yield variability at all. It is concluded that variations in water availability after flowering (i.e. during the grain filling period) are a major factor in yield variability of faba beans in Western Europe. However, when water shortage is eliminated as the limiting factor, yield reducing factors, especially diseases, may be more important than was expected before. It is shown how feasibility studies with the model can support management and breeding research by evaluating 'ideotypes' and conditions for optimum productivity in present and future climate. As an example, some effects of climate change on average yield and yield variability of rain-fed and irrigated crops are assessed

Quantitative single-protein imaging reveals molecular complex formation of integrin, talin, and kindlin during cell adhesion

Single-molecule localization microscopy (SMLM) enabling the investigation of individual proteins on molecular scales has revolutionized how biological processes are analysed in cells. However, a major limitation of imaging techniques reaching single-protein resolution is the incomplete and often unknown labeling and detection efficiency of the utilized molecular probes. As a result, fundamental processes such as complex formation of distinct molecular species cannot be reliably quantified. Here, we establish a super-resolution microscopy framework, called quantitative single-molecule colocalization analysis (qSMCL), which permits the identification of absolute molecular quantities and thus the investigation of molecular-scale processes inside cells. The method combines multiplexed single-protein resolution imaging, automated cluster detection, in silico data simulation procedures, and widely applicable experimental controls to determine absolute fractions and spatial coordinates of interacting species on a true molecular level, even in highly crowded subcellular structures. The first application of this framework allowed the identification of a long-sought ternary adhesion complex-consisting of talin, kindlin and active beta 1-integrin-that specifically forms in cell-matrix adhesion sites. Together, the experiments demonstrate that qSMCL allows an absolute quantification of multiplexed SMLM data and thus should be useful for investigating molecular mechanisms underlying numerous processes in cells. Single-molecule localisation microscopy is limited by low labeling and detection efficiencies of the molecular probes. Here the authors report a framework to obtain absolute molecular quantities on a true molecular scale; the data reveal a ternary adhesion complex underlying cell-matrix adhesion