Effect of carbon/nitrogen ratio on carbohydrate metabolism and light energy dissipation mechanisms in Arabidopsis thaliana.
Carbon (C) and nitrogen (N) nutrient sources are essential elements for metabolism, and their availability must be tightly coordinated for the optimal growth and development in plants. Plants are able to sense and respond to different C/N conditions via specific partitioning of C and N sources and the regulation of a complex cellular metabolic activity. We studied how the interaction between C and N signaling could affect carbohydrate metabolism, soluble sugar levels, photochemical efficiency of photosystem II (PSII) and the ability to drive the excess energy in Arabidopsis seedlings under moderated and disrupted C/N-nutrient conditions. Invertase and sucrose synthase activities were markedly affected by C/N-nutrient status depending on the phosphorylation status, suggesting that these enzymes may necessarily be modulated by their direct phosphorylation or phosphorylation of proteins that form complex with them in response to C/N stress. In addition, the enzymatic activity of these enzymes was also correlated with the amount of sugars, which not only act as substrate but also as signaling compounds. Analysis of chlorophyll fluorescence in plants under disrupted C/N condition suggested a reduction of electron transport rate at PSII level associated with a higher capacity for non-radiative energy dissipation in comparison with plants under moderated C/N condition. In conclusion, the tight coordination between C and N not only affects the carbohydrates metabolism and their concentration within plant tissues, but also the partitioning of the excitation energy at PSII level between radiative (electron transport) and non-radiative (heat) dissipation pathways.
Department of Agriculture, Food and Environment, University of Pisa, Via Mariscoglio 34, I-56017, Pisa, Italy.
Thais
T
Huarancca Reyes
Istituto di Biologia Agro-ambientale e Forestale (IBAF), Consiglio Nazionale delle Ricerche, Via Salaria km 29,300, 00016, Monterotondo Scalo (RM), Italy.
Andrea
A
Scartazza
Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku N10-W8, Sapporo, 060-0810, Japan.
Yu
Y
Lu
Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku N10-W8, Sapporo, 060-0810, Japan.
Junji
J
Yamaguchi
Department of Agriculture, Food and Environment, University of Pisa, Via Mariscoglio 34, I-56017, Pisa, Italy. Electronic address: lorenzo.guglielminetti@unipi.it.
Lorenzo
L
Guglielminetti
D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000528:radiation effects*; D050260:Carbohydrate Metabolism / Q000187:drug effects*; D002244:Carbon / Q000494:pharmacology*; D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D007527:Isoenzymes / Q000378:metabolism; D008027:Light; D009584:Nitrogen / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D012995:Solubility; D013312:Stress, Physiological / Q000187:drug effects; D013997:Time Factors
D007527:Isoenzymes; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D002244:Carbon; D009584:Nitrogen
C/N-nutrient; Chlorophyll fluorescence; Invertase; Phosphorylation state; Soluble sugars; Sucrose synthase