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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). Source

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 Source

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. Source

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. Source

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