title: Prolonged root hypoxia induces ammonium accumulation and decreases the nutritional quality of tomato fruits.
abstract: Here we examined the effects of root hypoxia (1-2% oxygen) on the physiology of the plant and on the biochemical composition of fruits in tomato (Solanum lycopersicum cv. Micro-Tom) plants submitted to gradual root hypoxia at first flower anthesis. Root hypoxia enhanced nitrate absorption with a concomitant release of nitrite and ammonium into the medium, a reduction of leaf photosynthetic activity and chlorophyll content, and an acceleration of fruit maturation, but did not affect final fruit size. Quantitative metabolic profiling of mature pericarp extracts by (1)H NMR showed that levels of major metabolites including sugars, organic acids and amino acids were not modified. However, ammonium concentration increased dramatically in fruit flesh, and ascorbate and lycopene concentrations decreased. Our data indicate that the unfavorable effects of root hypoxia on fruit quality cannot be explained by two of the well-known effects of root hypoxia on the plant, namely a decrease in photosynthesis or an excess in ethylene production, but may instead result from disturbances in the supply of either growth regulators or ammonium, by the roots.
authors.affiliation: Département des Sciences Biologiques, Faculté des Sciences de Tunis, UR d'Ecologie Végétale,Campus Universitaire, Tunis, Tunisia.
authors.forename: Faouzi
authors.initials: F
authors.lastname: Horchani
authors.forename: Philippe
authors.initials: P
authors.lastname: Gallusci
authors.forename: Pierre
authors.initials: P
authors.lastname: Baldet
authors.forename: Cécile
authors.initials: C
authors.lastname: Cabasson
authors.forename: Mickaël
authors.initials: M
authors.lastname: Maucourt
authors.forename: Dominique
authors.initials: D
authors.lastname: Rolin
authors.forename: Samira
authors.initials: S
authors.lastname: Aschi-Smiti
authors.forename: Philippe
authors.initials: P
authors.lastname: Raymond
mesh_terms: D015687:Cell Hypoxia; D005638:Fruit / Q000737:chemistry* / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D013312:Stress, Physiological; D014867:Water
chemical_list: D000644:Quaternary Ammonium Compounds; D014867:Water; D010100:Oxygen