Response of starch potato (Solanum tuberosum L.) genotypes to osmotic stress in vitro and drought stress in vivo

Potato (Solanum tuberosum L.) is one of the most important crops in the world. In addition to food and fodder, potato is also used for industrial purposes like production of adhesives, paper, and cosmetics. The vegetative growth phase of potato correlates with dry periods in spring and early summer, which are increased by climate change. Drought stress leads to morphological, physiological, and biochemical changes in the plant that have an extensive negative impact on the size and quality of the tubers. Since potato is a drought-sensitive species with its shallow root system, the interest in drought-tolerant cultivars is immense. Because ex vitro test systems are expensive and labor-intense and because additional parameters like other abiotic and biotic stressors influence the stress response, investigations in vitro are of great interest. Advantages of in vitro systems are the controlled light intensity, temperature, and supply of nutrients. Furthermore, pathogens can be excluded from the culture, and experiments require less space. Osmotic stress in vitro can be induced by adding an osmoticum, which lowers the osmotic potential in the culture medium. In the context of this work, an existing in vitro test system was optimised. For this purpose, the solid medium was replaced by liquid medium to enable that sorbitol can be added stepwise with increasing concentration. This resulted in two advantages: 1. the stress induction was gradual, and thus no osmotic shock was induced; 2. the plants were able to establish roots prior to the addition of the osmoticum, which allowed the stress that occurred by cutting the explants to be mitigated. This experiment showed that sorbitol was probably taken up by the roots and transported into the shoots, where it was detected by GC-MS. Furthermore, selected potato genotypes were investigated for their early drought stress response in open greenhouse and shelter experiments and their early osmotic stress response in vitro. For this purpose, candidate proteins for drought stress were selected after identification by LC-MS in material from rainout shelter trials. Identified proteins were further selected based on differential abundance in the genotypes ‘Eurostarch’ and ‘Tomba', which were postulated to be rather tolerant. From the identified candidate proteins, eight genes were selected, and their expression was investigated by RT-qPCR in leaves after seven days of water withdrawal in two trials in an open greenhouse, where differences between treatments but no genotypic effects were detected. Expression of peroxidase 51-like (POD), subtilase family protein (SBT1.7), and cell wall/vacuolar inhibitor of fructosidase (INH1) responded strongly to drought stress in all genotypes. Dry masses of the shoots also demonstrated stress induction ex vitro without reaching the permanent wilting point in the open greenhouse. The analysis under osmotic stress in two experiments in vitro also showed altered shoot dry mass and differential gene expression under osmotic stress. SBT1.7 was regulated in vitro in all genotypes under osmotic stress. POD showed similar regulation to the open greenhouse experiments in three of the four genotypes analysed. Furthermore, INH1 was only regulated in ‘Eurostrach’ and 'Tomba'. Additionally, 13-LOX, a gene of the family of lipoxygenases linked to osmotic adjustment, was upregulated in all genotypes under osmotic stress. Finally, differentially abundant proteins were identified in leaves of two shelter experiments under drought stress, nitrogen deficiency, and combined stress in two genotypes that differ in tolerance towards those stresses. Results showed differences in proteomic responses under combined as well as single stresses. The sensitive genotype ‘Kiebitz’ showed a higher abundance of proteases, whereas the rather tolerant genotype ‘Tomba’ showed a lower abundance of such proteins. In summary, important insights into the stress response of potato to drought stress and osmotic stress were gained. Further studies with earlier sampling could help to better understand genotypic differences and develop biomarkers for early drought stress. An alternative osmoticum for the in vitro system should be considered.BMEL/Nachwachsende Rohstoffe/22001917/E

Expression analysis of candidate genes as indicators for commencing drought stress in starch potatoes

Drought stress is a major problem for potato production and will be of grave importance due to climate change and the resulting temperature peaks along with drought periods in the vegetative growth phase of potato. Plants, as sessile organisms, adapt to their environment morphologically as well as biochemically. To cope better with abiotic stresses like drought, plants developed strategies like reactive oxygen species (ROS) detoxification and fast reacting stomatal closure, as well as signalling cascades leading to a quick response to stress. This study aimed at analysing eight genes of interest, derived from a former proteomic study, and determining their suitability for detection of commencing drought stress in early growth stages of potato. For this aim, six starch potato genotypes, which differed in stress response in previous studies, were examined for plant growth and physiological parameters in two experiments in an open greenhouse after seven and 14 days of stress. Besides lower shoot biomass after drought stress, which was already visible after seven days and became stronger after 14 days, weaker root growth was also detected after 14 days. The observed differences between the experiments can presumably be explained by temperature peaks and high radiation prior to and during the first experiment, which took place earlier in the year. The expression of the eight genes was studied in young leaves of four genotypes after 7 days of water withdrawal. Gene expression patterns were dependent on the studied genes. Three genes, cell wall/vacuolar inhibitor of fructosidase (INH1), peroxidase 51-like (POD) and subtilase family protein (SBT1.7) showed consistent changes in gene expression after seven days of stress between all genotypes. The INH1 gene was found to be upregulated in all genotypes in two independent experiments after drought stress. This correlates with the results at the protein level, where INH1 was also found to be higher abundant in two genotypes of potato (Wellpott et al., DGG-Proceedings 10, 2021). Therefore, this gene might be an appropriate candidate for the detection of commencing drought stress in potato

Liquid in vitro culture system allows gradual intensification of osmotic stress in Solanum tuberosum through sorbitol

Abstract: Because of their shallow root system, drought stress is a major problem in potato cultivation. Due to climate change more severe drought periods are expected to occur in the vegetative growth phase of potato growth. Therefore, there is a great need for drought tolerant potato genotypes. Potato responds to drought stress in the field in various ways, including osmoregulation. Osmotic stress can be induced in vitro by adding an osmotic agent and thus lowering the osmotic potential of the medium. In this study, a new, cost-effective in vitro test system is presented, in which the osmotic agent can be gradually added after root formation to prevent an osmotic shock. This is achieved by using sieves as plant holders and liquid medium, which, allows an improved simulation of gradually drying soil. Responses to osmotic stress in four potato genotypes were analysed and an increase in proline under osmotic stress was detected. Moreover, genes of interest that were postulated to be linked to drought stress were shown by quantitative qRT-PCR to be regulated under osmotic stress. Furthermore, we showed that the content of sorbitol, which was used as osmotic agent, was 700- fold higher for ‘Eurostarch’ after seven days under osmotic stress and 1093- fold higher after 14 days, respectively, compared to control plants without sorbitol addition. Therefore, further investigations must show, whether it was taken up through the roots, is metabolised, stored or de novo synthesised by the potato plants. Keypoints: The established novel in vitro test system for potato allows gradually increasing stress exposition of rooted plants. Sorbitol seems not an ideal osmotic agent as it is likely taken up

Flow rate and source reservoir identification from airborne chemical sampling of the uncontrolled Elgin platform gas release

An uncontrolled gas leak from 25 March to 16 May 2012 led to evacuation of the Total Elgin wellhead and neighbouring drilling and production platforms in the UK North Sea. Initially the atmospheric flow rate of leaking gas and condensate was very poorly known, hampering environmental assessment and well control efforts. Six flights by the UK FAAM chemically instrumented BAe-146 research aircraft were used to quantify the flow rate. The flow rate was calculated by assuming the plume may be modelled by a Gaussian distribution with two different solution methods: Gaussian fitting in the vertical and fitting with a fully mixed layer. When both solution methods were used they compared within 6% of each other, which was within combined errors. Data from the first flight on 30 March 2012 showed the flow rate to be 1.3±0.2kgCH4s-1, decreasing to less than half that by the second flight on 17 April 2012. δ13CCH4 in the gas was found to be -43‰, implying that the gas source was unlikely to be from the main high pressure, high temperature Elgin gas field at 5.5km depth, but more probably from the overlying Hod Formation at 4.2km depth. This was deemed to be smaller and more manageable than the high pressure Elgin field and hence the response strategy was considerably simpler. The first flight was conducted within 5 days of the blowout and allowed a flow rate estimate within 48h of sampling, with δ13CCH4 characterization soon thereafter, demonstrating the potential for a rapid-response capability that is widely applicable to future atmospheric emissions of environmental concern. Knowledge of the Elgin flow rate helped inform subsequent decision making. This study shows that leak assessment using appropriately designed airborne plume sampling strategies is well suited for circumstances where direct access is difficult or potentially dangerous. Measurements such as this also permit unbiased regulatory assessment of potential impact, independent of the emitting party, on timescales that can inform industry decision makers and assist rapid-response planning by government

Co-ordinated Airborne Studies in the Tropics (CAST)

This is the author accepted manuscript. The final version is available from the American Meteorological Society via http://dx.doi.org/10.1175/BAMS-D-14-00290.1The Co-ordinated Airborne Studies in the Tropics (CAST) project is studying the chemical composition of the atmosphere in the Tropical Warm Pool region to improve understanding of trace gas transport in convection. The main field activities of the CAST (Co-ordinated Airborne Studies in the Tropics) campaign took place in the West Pacific in January/February 2014. The field campaign was based in Guam (13.5°N, 144.8°E) using the UK FAAM BAe-146 atmospheric research aircraft and was coordinated with the ATTREX project with the unmanned Global Hawk and the CONTRAST campaign with the Gulfstream V aircraft. Together, the three aircraft were able to make detailed measurements of atmospheric structure and composition from the ocean surface to 20 km. These measurements are providing new information about the processes influencing halogen and ozone levels in the tropical West Pacific as well as the importance of trace gas transport in convection for the upper troposphere and stratosphere. The FAAM aircraft made a total of 25 flights between 1°S-14°N and 130°-155°E. It was used to sample at altitudes below 8 km with much of the time spent in the marine boundary layer. It measured a range of chemical species, and sampled extensively within the region of main inflow into the strong West Pacific convection. The CAST team also made ground-based measurements of a number of species (including daily ozonesondes) at the Atmospheric Radiation Measurement program site on Manus Island, Papua New Guinea (2.1°S, 147.4°E). This article presents an overview of the CAST project focussing on the design and operation of the West Pacific experiment. It additionally discusses some new developments in CAST, including flights of new instruments on the Global Hawk in February/March 2015.CAST is funded by NERC and STFC, with grant NE/ I030054/1 (lead award), NE/J006262/1, NE/J006238/1, NE/J006181/1, NE/J006211/1, NE/J006061/1, NE/J006157/1, NE/J006203/1, NE/J00619X/1, and NE/J006173/1. N. R. P. Harris was supported by a NERC Advanced Research Fellowship (NE/G014655/1). P. I. Palmer acknowledges his Royal Society Wolfson Research Merit Award. The BAe-146-301 Atmospheric Research Aircraft is flown by Directflight Ltd and managed by the Facility for Airborne Atmospheric Measurements, which is a joint entity of the Natural Environment Research Council and the Met Office. The authors thank the staff at FAAM, Directflight and Avalon Aero who worked so hard toward the success of the aircraft deployment in Guam, especially for their untiring efforts when spending an unforeseen 9 days in Chuuk. We thank the local staff at Chuuk and Palau, as well as the authorities in the Federated States of Micronesia for their help in facilitating our research flights. Special thanks go to the personnel associated with the ARM facility at Manus, Papua New Guinea without whose help the ground-based measurements would not have been possible. Thanks to the British Atmospheric Data Centre (BADC) for hosting our data and the NCAS Atmospheric Measurement Facility for providing the radiosonde and ground-based ozone equipment. Chlorophyll-a data used in Figure 1 were extracted using the Giovanni online data system, maintained by the NASA GES DISC. We also acknowledge the MODIS mission scientists and associated NASA personnel for the production of this data set. Finally we thank many individual associated with the ATTREX and CONTRAST campaigns for their help in the logistical planning, and we would like to single out Jim Bresch for his excellent and freely provided meteorological advice

Combined nitrogen and drought stress leads to overlapping and unique proteomic responses in potato

Main conclusion: Nitrogen deficient and drought-tolerant or sensitive potatoes differ in proteomic responses under combined (NWD) and individual stresses. The sensitive genotype ‘Kiebitz’ exhibits a higher abundance of proteases under NWD. Abstract: Abiotic stresses such as N deficiency and drought affect the yield of Solanum tuberosum L. tremendously. Therefore, it is of importance to improve potato genotypes in terms of stress tolerance. In this study, we identified differentially abundant proteins (DAPs) in four starch potato genotypes under N deficiency (ND), drought stress (WD), or combined stress (NWD) in two rain-out shelter experiments. The gel-free LC–MS analysis generated a set of 1177 identified and quantified proteins. The incidence of common DAPs in tolerant and sensitive genotypes under NWD indicates general responses to this stress combination. Most of these proteins were part of the amino acid metabolism (13.9%). Three isoforms of S-adenosyl methionine synthase (SAMS) were found to be lower abundant in all genotypes. As SAMS were found upon application of single stresses as well, these proteins appear to be part of the general stress response in potato. Interestingly, the sensitive genotype ‘Kiebitz’ showed a higher abundance of three proteases (subtilase, carboxypeptidase, subtilase family protein) and a lower abundance of a protease inhibitor (stigma expressed protein) under NWD stress compared to control plants. The comparably tolerant genotype ‘Tomba’, however, displayed lower abundances of proteases. This indicates a better coping strategy for the tolerant genotype and a quicker reaction to WD when previously stressed with ND

Coordinated airborne studies in the tropics (CAST)

This is the final version of the article. It first appeared from the American Meteorological Society via http://dx.doi.org/10.1175/BAMS-D-14-00290.1Abstract The main field activities of the Coordinated Airborne Studies in the Tropics (CAST) campaign took place in the west Pacific during January–February 2014. The field campaign was based in Guam (13.5°N, 144.8°E), using the U.K. Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 atmospheric research aircraft, and was coordinated with the Airborne Tropical Tropopause Experiment (ATTREX) project with an unmanned Global Hawk and the Convective Transport of Active Species in the Tropics (CONTRAST) campaign with a Gulfstream V aircraft. Together, the three aircraft were able to make detailed measurements of atmospheric structure and composition from the ocean surface to 20 km. These measurements are providing new information about the processes influencing halogen and ozone levels in the tropical west Pacific, as well as the importance of trace-gas transport in convection for the upper troposphere and stratosphere. The FAAM aircraft made a total of 25 flights in the region between 1°S and 14°N and 130° and 155°E. It was used to sample at altitudes below 8 km, with much of the time spent in the marine boundary layer. It measured a range of chemical species and sampled extensively within the region of main inflow into the strong west Pacific convection. The CAST team also made ground-based measurements of a number of species (including daily ozonesondes) at the Atmospheric Radiation Measurement Program site on Manus Island, Papua New Guinea (2.1°S, 147.4°E). This article presents an overview of the CAST project, focusing on the design and operation of the west Pacific experiment. It additionally discusses some new developments in CAST, including flights of new instruments on board the Global Hawk in February–March 2015.CAST is funded by NERC and STFC, with grant NE/ I030054/1 (lead award), NE/J006262/1, NE/J006238/1, NE/J006181/1, NE/J006211/1, NE/J006061/1, NE/J006157/1, NE/J006203/1, NE/J00619X/1, and NE/J006173/1. N. R. P. Harris was supported by a NERC Advanced Research Fellowship (NE/G014655/1). P. I. Palmer acknowledges his Royal Society Wolfson Research Merit Award. The BAe-146-301 Atmospheric Research Aircraft is flown by Directflight Ltd and managed by the Facility for Airborne Atmospheric Measurements, which is a joint entity of the Natural Environment Research Council and the Met Office. The authors thank the staff at FAAM, Directflight and Avalon Aero who worked so hard toward the success of the aircraft deployment in Guam, especially for their untiring efforts when spending an unforeseen 9 days in Chuuk. We thank the local staff at Chuuk and Palau, as well as the authorities in the Federated States of Micronesia for their help in facilitating our research flights. Special thanks go to the personnel associated with the ARM facility at Manus, Papua New Guinea without whose help the ground-based measurements would not have been possible. Thanks to the British Atmospheric Data Centre (BADC) for hosting our data and the NCAS Atmospheric Measurement Facility for providing the radiosonde and ground-based ozone equipment. Chlorophyll-a data used in Figure 1 were extracted using the Giovanni online data system, maintained by the NASA GES DISC. We acknowledge the MODIS mission scientists and associated NASA personnel for the production of this data set. Finally we thank many individuals associated with the ATTREX and CONTRAST campaigns for their help in the logistical planning, and we would like to single out Jim Bresch for his excellent and freely provided meteorological advice

Kinetics of cone specific G-protein signaling in avian photoreceptor cells

Cone photoreceptor cells of night-migratory songbirds seem to process the primary steps of two different senses, vision and magnetoreception. The molecular basis of phototransduction is a prototypical G protein-coupled receptor pathway starting with the photoexcitation of rhodopsin or cone opsin thereby activating a heterotrimeric G protein named transducin. This interaction is well understood in vertebrate rod cells, but parameter describing protein–protein interactions of cone specific proteins are rare and not available for migratory birds. European robin is a model organism for studying the orientation of birds in the earth magnetic field. Recent findings showed a link between the putative magnetoreceptor cryptochrome 4a and the cone specific G-protein of European robin. In the present work, we investigated the interaction of European robin cone specific G protein and cytoplasmic regions of long wavelength opsin. We identified the second loop in opsin connecting transmembrane regions three and four as a critical binding interface. Surface plasmon resonance studies using a synthetic peptide representing the second cytoplasmic loop and purified G protein α-subunit showed a high affinity interaction with a KD value of 21 nM. Truncation of the G protein α-subunit at the C-terminus by six amino acids slightly decreased the affinity. Our results suggest that binding of the G protein to cryptochrome can compete with the interaction of G protein and non-photoexcited long wavelength opsin. Thus, the parallel presence of two different sensory pathways in bird cone photoreceptors is reasonable under dark-adapted conditions or during illumination with short wavelengths

The motion of trees in the wind: a data synthesis

Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees, and wind is a key disturbance agent in many of the world\u27s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically important, rather than broadleaf forests, which dominate the forest carbon cycle. This study brings together tree motion time-series data to systematically evaluate the factors influencing tree responses to wind loading, including data from both broadleaf and coniferous trees in forests and open environments. We found that the two most descriptive features of tree motion were (a) the fundamental frequency, which is a measure of the speed at which a tree sways and is strongly related to tree height, and (b) the slope of the power spectrum, which is related to the efficiency of energy transfer from wind to trees. Intriguingly, the slope of the power spectrum was found to remain constant from medium to high wind speeds for all trees in this study. This suggests that, contrary to some predictions, damping or amplification mechanisms do not change dramatically at high wind speeds, and therefore wind damage risk is related, relatively simply, to wind speed. Conifers from forests were distinct from broadleaves in terms of their response to wind loading. Specifically, the fundamental frequency of forest conifers was related to their size according to the cantilever beam model (i.e. vertically distributed mass), whereas broadleaves were better approximated by the simple pendulum model (i.e. dominated by the crown). Forest conifers also had a steeper slope of the power spectrum. We interpret these finding as being strongly related to tree architecture; i.e. conifers generally have a simple shape due to their apical dominance, whereas broadleaves exhibit a much wider range of architectures with more dominant crowns