title: Nitrogen Limited Red and Green Leaf Lettuce Accumulate Flavonoid Glycosides, Caffeic Acid Derivatives, and Sucrose while Losing Chlorophylls, Β-Carotene and Xanthophylls.
abstract: Reduction of nitrogen application in crop production is desirable for ecological and health-related reasons. Interestingly, nitrogen deficiency can lead to enhanced concentrations of polyphenols in plants. The reason for this is still under discussion. The plants' response to low nitrogen concentration can interact with other factors, for example radiation intensity. We cultivated red and green leaf lettuce hydroponically in a Mediterranean greenhouse, supplying three different levels of nitrogen (12 mM, 3 mM, 0.75 mM), either in full or reduced (-50%) radiation intensity. In both red and green lettuce, we found clear effects of the nitrogen treatments on growth characteristics, phenolic and photosynthetic compounds, nitrogen, nitrate and carbon concentration of the plants. Interestingly, the concentrations of all main flavonoid glycosides, caffeic acid derivatives, and sucrose increased with decreasing nitrogen concentration, whereas those of chlorophylls, β-carotene, neoxanthin, lactucaxanthin, all trans- and cis-violaxanthin decreased. The constitutive concentrations of polyphenols were lower in the green cultivar, but their relative increase was more pronounced than in the red cultivar. The constitutive concentrations of chlorophylls, β-carotene, neoxanthin, all trans- and cis-violaxanthin were similar in red and green lettuce and with decreasing nitrogen concentration they declined to a similar extent in both cultivars. We only detected little influence of the radiation treatments, e.g. on anthocyanin concentration, and hardly any interaction between radiation and nitrogen concentration. Our results imply a greater physiological plasticity of green compared to the red lettuce regarding its phenolic compounds. They support the photoprotection theory regarding anthocyanins as well as the theory that the deamination activity of phenylalanine ammonia-lyase drives phenylpropanoid synthesis.
authors.affiliation: Department of Modelling and Knowledge Transfer, Leibniz Institute of Vegetable and Ornamental Crops e.V., Grossbeeren, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Becker
authors.affiliation: Department of Plant Sciences, Institute for Adriatic Crops and Karst Reclamation, Split, Croatia.
authors.forename: Branimir
authors.initials: B
authors.lastname: Urlić
authors.affiliation: Department of Applied Sciences, Institute for Adriatic Crops and Karst Reclamation, Split, Croatia.
authors.forename: Maja
authors.initials: M
authors.lastname: Jukić Špika
authors.affiliation: Department of Modelling and Knowledge Transfer, Leibniz Institute of Vegetable and Ornamental Crops e.V., Grossbeeren, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Kläring
authors.affiliation: Department of Plant Quality, Leibniz Institute of Vegetable and Ornamental Crops e.V., Grossbeeren, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Krumbein
authors.affiliation: Department of Plant Quality, Leibniz Institute of Vegetable and Ornamental Crops e.V., Grossbeeren, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Baldermann
authors.affiliation: Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia.
authors.forename: Smiljana
authors.initials: S
authors.lastname: Goreta Ban
authors.affiliation: Department of Applied Sciences, Institute for Adriatic Crops and Karst Reclamation, Split, Croatia.
authors.forename: Slavko
authors.initials: S
authors.lastname: Perica
authors.affiliation: Department of Plant Nutrition, Leibniz Institute of Vegetable and Ornamental Crops e.V., Grossbeeren, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schwarz
mesh_terms: D002109:Caffeic Acids / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis; D002244:Carbon / Q000032:analysis; D002734:Chlorophyll / Q000378:metabolism*; D005419:Flavonoids / Q000378:metabolism*; D005838:Genotype; D006027:Glycosides / Q000378:metabolism*; D018545:Lactuca / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis / Q000172:deficiency*; D010636:Phenols; D010650:Phenylalanine Ammonia-Lyase; D010788:Photosynthesis; D018515:Plant Leaves; D013395:Sucrose / Q000378:metabolism*; D024341:Xanthophylls / Q000378:metabolism*; D019207:beta Carotene / Q000378:metabolism*
chemical_list: D002109:Caffeic Acids; D002241:Carbohydrates; D005419:Flavonoids; D006027:Glycosides; D009566:Nitrates; D010636:Phenols; D024341:Xanthophylls; D019207:beta Carotene; D002734:Chlorophyll; D013395:Sucrose; D002244:Carbon; D010650:Phenylalanine Ammonia-Lyase; D009584:Nitrogen; C040048:caffeic acid