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Abiotic stress due to climate change with continuous rise of atmospheric CO2 concentration is predicted to cause severe changes to crop productivity. Thus, research into wheat cultivars, capable of maintaining yield under limiting conditions is necessary. The aim of this study was to investigate the physiological responses of spring wheat to individual and combined drought- and heat events and their interaction with CO2 concentration. Two heat sensitive (LM19, KU10) and two heat tolerant (LM62, GN5) genotypes were selected and grown under ambient (400 ppm, aCO2) and elevated (800 ppm, eCO2) CO2 concentrations. At the tillering stage, the wheat plants were subjected to different treatments: control, progressive drought, heat and combined drought and heat stress. Our results showed that eCO2 mitigated the negative impact of the moderate stress in all genotypes. However, no distinctive responses were observed in some of the measured parameters between heat sensitive and tolerant genotypes. All genotypes grown at eCO2 had significantly higher net photosynthetic rates and maintained maximum quantum efficiency of PSII photochemistry under heat and combined stress compared to aCO2. Under heat and combined stress, the chlorophyll a:b ratios decreased only in heat tolerant genotypes at eCO2 compared to the control. Furthermore, the heat tolerant genotypes grown at eCO2 showed an increased glucose and fructose contents and a decreased sucrose content under combined stress compared to aCO2. These findings provide new insights into the underlying mechanisms of different genotypic responses to combined abiotic stresses at eCO2 that differ from the response to individual stresses.

Ultraviolet radiation (UV, 280-400 nm) as an environmental signal triggers metabolic acclimatory responses. However, how different light qualities affect UV acclimation during growth is poorly understood. Here, cucumber plants (Cucumis sativus) were grown under blue, green, red, or white light in combination with UV. Their effects on leaf metabolites were determined using untargeted metabolomics. Blue and white growth light triggered the accumulation of compounds related to primary and secondary metabolism, including amino acids, phenolics, hormones, and compounds related to sugar metabolism and the TCA cycle. In contrast, supplementary UV in a blue or white light background decreased leaf content of amino acids, phenolics, sugars, and TCA-related compounds, without affecting abscisic acid, auxin, zeatin, or jasmonic acid levels. However, in plants grown under green light, UV-induced accumulation of phenolics, hormones (auxin, zeatin, dihydrozeatin-7-N-dihydrozeatin, jasmonic acid), amino acids, sugars, and TCA cycle-related compounds. Plants grown under red light with UV mainly showed decreased sugar content. These findings highlight the importance of the blue light component for metabolite accumulation. Also, data on interactions of UV with green light on the one hand, and blue or white light on the other, further contributes to our understanding of light quality regulation of plant metabolism., Funding agency:GUDP (Danish Ministry of Food, Agriculture and Fisheries), Denmark

Heat and drought events often occur concurrently as a consequence of climate change and have a severe impact on crop growth and yield. Besides, the accumulative increase in the atmospheric CO

Ultraviolet B (UV-B, 280 – 315 nm) and ultraviolet A (UV-A, 315-400 nm) radiation comprise small portions of the solar radiation but regulate many aspects of plant development, physiology and metabolism. Until now, how plants respond to UV-B in the presence of different light qualities is poorly understood. This study aimed to assess the effects of a low UV-B dose (0.912± 0.074 kJ m-2 day-1, at a 6 h daily UV exposure) in combination with four light treatments (blue, green, red and broadband white at 210 μmol m-2 s-1 Photosynthetic active radiation [PAR]) on morphological and physiological responses of cucumber (Cucumis sativus cv. ‘Lausanna RZ F1’). We explored the effects of light quality backgrounds on plant morphology, leaf gas exchange, chlorophyll fluorescence, epidermal pigment accumulation, and on acclimation ability to saturating light intensity. Our results showed that supplementary UV-B significantly decreased biomass accumulation in the presence of broad band white, blue and green light, but not under red light. UV‐B also reduced the photosynthetic efficiency of CO2 fixation (α) when combined with blue light. These plants, despite showing high accumulation of anthocyanins, were unable to cope with saturating light conditions. No significant effects of UV-B in combination with green light were observed for gas exchange and chlorophyll fluorescence parameters, but supplementary UV-B significantly increased chlorophyll and flavonol contents in the leaf epidermis. Plants grown under red light and UV-B significantly increased maximum photosynthetic rate and dark respiration compared to pure red light. Additionally, red and UV-B treated plants during with saturating light intensity showed an higher quantum yield of photosystem II (PSII), fraction of open PSII centres and electron transport rate and showed no effect on the apparent maximum quantum efficiency of PSII photochemistry (Fv/Fm) or non-photochemical quenching in contrast to solely red-light conditions. These findings provide new insights into how plants respond to UV-B radiation in the presence of different light spectra., Funding Agencies:GUDP (Danish Ministry of Food, Agriculture and Fisheries) Research center iFood Faculty for Business, Science and Technology at Örebro University Örebro University Vice Chancellor's strategic research programme on 'Food and Health'

During recent years we have advanced our understanding of plant molecular responses to ultraviolet radiation (UV, 280-400 nm); however, how plants respond to UV radiation under different spectral light qualities is poorly understood. In this study, cucumber plants (Cucumis sativus ‘Lausanna RZ F1’) were grown under monochromatic blue, green, red and broadband white light in combination with UV radiation. The effects of light quality and UV radiation on acclimatory responses were assessed by measuring transcript accumulation of ELONGATED HYPOCOTYL 5 (HY5), CHALCONE SYNTHASE 2 (CHS2) and LIGHT HARVESTING COMPLEX II (LHCII), and the accumulation of flavonoids and hydroxycinnamic acids in the leaves. The growth light backgrounds differentially regulated gene expression and metabolite accumulation. While HY5 and CHS2 transcripts were induced by blue and white light, LHCII was induced by white and red light. Furthermore, UV radiation antagonized the effects of blue, red, green, and white light on transcript accumulation in a gene dependent manner. Plants grown under blue light with supplementary UV radiation increased phenylalanine, flavonol disaccharide I and caffeic acid contents compared to those exposed only to blue light. UV radiation also induced the accumulation of flavonol disaccharide I and II, ferulic acid hexose and coumaric acid hexose in plants grown under green light. Our findings provide further understanding of plant responses to UV radiation in combination with different light spectra and contribute to the design of light recipes for horticultural practices that aim to modify plant metabolism and ultimately improve crop quality., Funding agencies:GUDP (Danish Ministry of Food, Agriculture and Fisheries)Faculty for Business, Science and Technology at Örebro UniversityÖrebro University

Abiotic stress due to climate change with continuous rise of atmospheric CO

LED diskuteres meget, ogsa til lokal dyrkning i lukkede rum. Men hvordan er status, og hvad er de st0rste udfordringer?Oet kaster projektet Intelligent Light lys over.