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Topbjerg H.B.,Copenhagen University | Kaminski K.P.,University of Aarhus | Kaminski K.P.,University of Aalborg | Markussen B.,Copenhagen University | And 5 more authors.
Scientia Horticulturae | Year: 2014

Optimizing crops water use is essential for ensuring food production under future climate scenarios. Therefore, new cultivars that are capable of maintaining production under limited water resource are needed. This study screened for clonal differences in intrinsic water use efficiency (WUEi) within a dihaploid potato (Solanum tuberosum L.) mapping population under well-watered (WW) and drought-stress (DS) conditions. The factorial dependency of WUEi on several plant bio-physiological traits was analyzed, and clonal difference of WUEi was compared. Significant differences in WUEi were found among the clones within the population. Under WW the two clones showing the highest WUEi were significantly different from the two lowest WUEi performing clones. This could only be seen as a trend under DS. Under WW, WUEi differences were closely associated to net photosynthetic rate (An) and nitrogen isotope composition (δ15N) in the leaf biomass, but did not relate to stomatal conductance (gs) and carbon isotope composition (δ13C) in the leaf biomass. An was found to correlate significantly with leaf nitrogen concentration ([N]leaf) and chlorophyll content index (CCI) under WW. Leaf abscisic acid concentration did not correspond to the changes in gs, indicating that other factors might have been involved in controlling gs among the different clones. Collectively, the clonal differences in WUEi were attributed mainly to the variation in An, which in turn was influenced by plant N metabolism. Clones with high WUEi could be potentially used as material in future breeding programs. Furthermore CCI seemed to be a reliable tool in estimating the clonal An and thereby WUEi. © 2014 Elsevier B.V.


Kaminski K.P.,University of Aalborg | Korup K.,University of Aarhus | Andersen M.N.,University of Aarhus | Sonderkaer M.,University of Aalborg | And 3 more authors.
Theoretical and Applied Genetics | Year: 2015

Key message: WUE phenotyping and subsequent QTL analysis revealed cytosolic GS genes importance for limiting N loss due to photorespiration under well-watered and well-fertilized conditions. Abstract: Potato (Solanum tuberosum L.) closes its stomata at relatively low soil water deficits frequently encountered in normal field conditions resulting in unnecessary annual yield losses and extensive use of artificial irrigation. Therefore, unraveling the genetics underpinning variation in water use efficiency (WUE) of potato is important, but has been limited by technical difficulties in assessing the trait on individual plants and thus is poorly understood. In this study, a mapping population of potatoes has been robustly phenotyped, and considerable variation in WUE under well-watered conditions was observed. Two extreme WUE bulks of clones were identified and pools of genomic DNA from them as well as the parents were sequenced and mapped to reference potato genome. Following a novel data analysis approach, two highly resolved QTLs were found on chromosome 1 and 9. Interestingly, three genes encoding isoforms of cytosolic glutamine synthase were located in the QTL at chromosome 1 suggesting a major contribution of this enzyme to photosynthetic efficiency and thus WUE in potato. Indeed, Glutamine synthetase enzyme activity of leaf extracts was measured and found to be correlated with contrasting WUE phenotypes. © 2015, The Author(s).


Kaminski K.P.,University of Aalborg | Korup K.,University of Aarhus | Andersen M.N.,University of Aarhus | Sonderkaer M.,University of Aalborg | And 3 more authors.
Potato Research | Year: 2016

Potatoes and other Solanaceae species produce biologically active secondary metabolites called steroidal glycoalkaloids (GAs) which have antimicrobial, fungicidal, antiviral and insecticidal properties. GAs are, however, also toxic to animals and humans. Compared to wild species of potato, the elite cultivars primarily used for everyday consumption have very low contents of GAs. Breeding for important agronomical traits, like e.g. pathogen resistance, often requires the use of wild species and a situation where offspring have unacceptable high contents of GAs quite frequently arises. Knowledge of metabolic pathways leading to the synthesis of GAs, as well as of the genes that are responsible for the observed differences in plant and tuber GA content is only partial. The primary purpose of this study was to identify genomic regions and candidate genes responsible for differential GA content within a diploid potato mapping population (n = 90) that shows a high variation in GA accumulation. The analysis was performed using a novel method based on next generation genome sequencing. A region on chromosome 1 was found to be associated with differential GA content. Within that region, sterol 24-C-methyltransferase (SMT1), sterol desaturase (SD) and C-4 sterol methyl oxidase (SMO) genes were found, all encoding critical enzymes in the synthesis of the GAs precursor cholesterol. © 2016 European Association for Potato Research


Kaminski K.P.,University of Aarhus | Kaminski K.P.,University of Aalborg | Korup K.,University of Aarhus | Nielsen K.L.,University of Aalborg | And 4 more authors.
Agricultural and Forest Meteorology | Year: 2014

In spite of the agricultural importance of potato (Solanum tuberosum L.), most plant physiology studies have not accounted for the effect of the interaction between elevated carbon dioxide concentration ([CO2]) and other consequences of climate change on WUE. In 2010, a first controlled environment chamber experiment (E1) was performed with two treatments: one control at a [CO2] exposure level of 380ppm and the other at elevated [CO2] first to 700ppm and subsequently to 1000ppm. Plants grown at elevated [CO2] levels of 700 and 1000ppm showed a consistent significant increase in leaf level photosynthetic water use efficiency (pWUE) by stimulation in net photosynthesis rate (62% and 43% increase of An) with coincident decline in both stomatal conductance (21% and 43% decrease of gs) and leaf transpiration rate (19% and 40% decrease of E) resulting in pWUE increments of 89% and 147%. Furthermore, the ratio of leaf intercellular [CO2] to ambient air [CO2] (ci/ca) remained unchanged among treatments. In 2011, a second experiment was performed (E2), where two treatments comprised [CO2] levels of 380ppm (control) and elevated of 1000ppm. The plants were subjected to three temperature levels (14, 21 and 28°C). This procedure provided for investigation of WUE dependence of temperature at different [CO2]. At leaf-level, a consistent increase in pWUE of 28% across the three temperature levels was observed, caused by a significant stimulation in net photosynthesis rate (16%), and a significant decreased stomatal conductance (25%) with a simultaneous drop in transpiration rate although not significant. The ratio ci/ca was in contrast to the first experiment significantly higher in plants grown at elevated [CO2]. Despite this photosynthetic acclimation, concurrent stimulation of aboveground and belowground biomass accumulation was observed at elevated [CO2], resulting in higher harvest indices and irrigation WUE (45%), not significantly different from the increase of pWUE. Out of four cultivars investigated, the largest increase in irrigation WUE was found in the cultivar Ballerina, which also showed a six time increase in tuber yield, perhaps indicating less overall inhibition of photosynthesis by sugar accumulation. At all temperature levels, WUE was significantly larger at high [CO2]. This was the result of increased net photosynthesis rate (at low temperature), decreased transpiration rate and stomatal conductance (high temperature) or a combination of those two responses (moderate temperature). The results signify that beneficial effects of potato plant cultivation at elevated [CO2] comprise increased WUE at various temperature levels, but due to acclimation of photosynthesis the increase was smaller during prolonged than stepwise exposure. The experiment also showed that, in the conditions of climate change, associated higher T could decrease the response of photosynthesis to higher [CO2] and higher vapor pressure deficit will decrease the gain in WUE. © 2013 The Authors.


Merz U.,ETH Zurich | Lees A.K.,James Hutton Institute | Sullivan L.,James Hutton Institute | Schwarzel R.,Agroscope ACW Changins | And 4 more authors.
Plant Pathology | Year: 2012

Powdery scab of potato caused by Spongospora subterranea is one of the main disease problems in many potato production regions of the world. However, no efficient and economically sound control method is currently available. Host resistance will be a key component of the integrated management of powdery scab, but there are discrepancies in published powdery scab resistance ratings of cultivars between countries. In order to identify the main factors causing such discrepancies, 10 reference cultivars thought to have a range of susceptibility to powdery scab and potato mop-top virus were cropped over 4years in four to six locations across Europe and disease levels on roots and tubers were assessed using standardized scoring scales. Soil contamination was tested using real-time PCR and ELISA. The cultivars performed as expected according to previous characterization, with one exception. No relationship was found between tuber and root susceptibility. Assessment of powdery scab symptoms 1month before harvest gave results comparable to those assessed 2months after harvest. Neither real-time PCR nor ELISA soil test results were closely related to disease index data. The field trial results indicate that different scoring methods are the main factor for the discrepancy in resistance ratings, and that environmental conditions and/or soil inoculum level play a minor role. Furthermore, there was either no difference between the pathogen populations in each location or the resistance of most of the cultivars is polygenic. © 2011 The Authors. Plant Pathology © 2011 BSPP.


Kaminski K.P.,University of Aarhus | Kaminski K.P.,University of Aalborg | Korup K.,University of Aarhus | Kristensen K.,University of Aarhus | And 5 more authors.
Journal of Agronomy and Crop Science | Year: 2015

Potatoes (Solanum tuberosum L.) are drought-sensitive and more efficient water use, while maintaining high yields is required. Here, water-use efficiency (WUE) of a mapping population comprising 144 clones from a cross between 90-HAF-01 (Solanum tuberosum1) and 90-HAG-15 (S. tuberosum2 × S. sparsipilum) was measured on well-watered plants under controlled-environment conditions combining three levels of each of the factors: [CO2], temperature, light, and relative humidity in growth chambers. The clones were grouped according to their photosynthetic WUE (pWUE) and whole-plant WUE (wpWUE) during experiments in 2010. Two offspring groups according to pWUE and wpWUE were identified on the basis of experiments conducted in 2010, which in experiments in 2011 again showed significant differences in pWUE (46 %, P < 0.001) and wpWUE (34 %, P < 0.001). The high-WUE group had a higher net photosynthesis rate (34 %) and dry matter accumulation (55 %, P < 0.001) rather than leaf-level transpiration rate (-4 %, no significant difference) or whole-plant water use (16 %). The pWUE correlated negatively to the ratio between leaf-internal and leaf-external [CO2] (R2 = -0.86 in 2010 and R2 = -0.83 in 2011, P < 0.001). The leaf chlorophyll content was lower in the high-WUE group indicating that the higher net photosynthesis rate was not due to higher leaf-N status. Less negative value of carbon isotope discrimination (δ13C) in the high-WUE group was only found in 2011. A modified Ball-Berry model was fitted to measured stomatal conductance (gs) under the systematically varied environmental conditions to identify parameter differences between the two groups, which could explain their contrasting WUE. Compared to the low-WUE group, the high-WUE group showed consistently lower values of the parameter m, which is inversely related to WUE. Differences related specifically to the dependence of gs on humidity and net photosynthesis rate were only found in 2010. The lower ratio between leaf-internal and leaf-external [CO2] and higher WUE of the high-WUE group was consistent over a wide range of air vapour pressure deficits from 0.5 to 3.5 kPa. The mapping population was normally distributed with respect to WUE suggesting a multigenic nature of this trait. The WUE groups identified can be further employed for quantitative trait loci (QTL) analysis by use of gene expression studies or genome resequencing. The differences in population WUE indicate a genetic potential for improvement of this trait. © 2014 Blackwell Verlag GmbH.


Topbjerg H.B.,Copenhagen University | Kaminski K.P.,University of Aarhus | Kaminski K.P.,University of Aalborg | Korup K.,University of Aarhus | And 4 more authors.
Acta Agriculturae Scandinavica Section B: Soil and Plant Science | Year: 2015

A drought screening experiment focusing on intrinsic water use efficiency (WUEi) was carried out among 132 clones belonging to a dihaploid potato mapping population. The clones were exposed to progressive soil drying during a five-day period in a greenhouse pot experiment. Analysis of the underlying variables was done based on a multivariate data analysis strategy. The strategy successfully divided the clones into WUEi performance categories. Differences between clonal WUEi responses were traced back to differences in the net photosynthetic rate. Stomatal conductance (gs) did not vary significantly between the clones. Leaf abscisic acid (ABA) concentration and leaf water potential were found to reflect known isohydric behaviour for potato, and a non-linear relationship could be established for gs and leaf ABA concentration across the WUEi groups. Similarly, a common non-linear relationship between leaf ABA concentration and soil water potential was found. The latter findings suggest that the investigated population did not harbour significant genetic variation as to ABA production as function of soil desiccation level or with respect to the sensitivity of stomatal aperture vis-à-vis leaf ABA concentration and soil water potential. © 2015, © 2015 Taylor & Francis.


Santala J.,University of Helsinki | Samuilova O.,University of Helsinki | Hannukkala A.,Mtt Agrifood Research Finland | Latvala S.,Mtt Agrifood Research Finland | And 35 more authors.
Annals of Applied Biology | Year: 2010

Potato mop-top virus (PMTV; genus Pomovirus; family Virgaviridae) is transmitted by the soil-borne Spongospora subterranea f.sp. subterranea, a protoctist that causes powdery scab on potato. PMTV is distributed widely in the potato growing areas in South and North America, Japan and northwestern Europe. This article reviews the current knowledge on detection, distribution and control of PMTV with focus on the Baltic Sea region. Since the 1980s, PMTV has caused great economic losses to potato production in the Nordic countries (Norway, Sweden, Denmark and Finland), but its occurrence in other countries of the Baltic Sea region remained unknown. To fill this knowledge gap, harmonised sampling and virus detection procedures including bioassays and serological and molecular methods were employed by 21 research institutions to detect PMTV in potato tubers and soil samples in 2005-2008. Potato growing areas were widely contaminated with PMTV in the Nordic countries. Only the main seed potato production area in northern Sweden and the High Grade seed potato production zone in Finland were negative for PMTV. Intensive and systematic surveys in Poland in 2004-2008 found no evidence of PMTV, except a single PMTV-infected tuber detected in 2008. Surveys in the Baltic countries (Lithuania, Latvia and Estonia) and northwestern Russia (Leningrad province) were negative for PMTV, except infection of minitubers in a screenhouse in Latvia in 2005. Varying percentages of tubers expressing spraing symptoms in Sweden, Norway, Denmark and Poland were infected with Tobacco rattle virus, and bioassays indicated similar results for Russia. Incidence of symptomless infections with PMTV was high in tubers of many potato cultivars. Here, we discuss the contrasting patterns of distribution of PMTV in the Baltic Sea region, factors playing a role in dispersal and establishment of PMTV in new fields and means for controlling PMTV and its spread to new areas. We emphasise the use of the current virus-specific methods for the detection of PMTV in symptomless potato tubers and the high risks of disseminating PMTV to new fields and areas in viruliferous resting spores of S. subterranea in the soil adhering to seed tubers. PMTV-resistant potato cultivars will provide the only sustainable means for preventing yield losses in the infested fields and the prospects of resistance breeding are summarised. © 2010 Association of Applied Biologists.

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