Salt stress-induced production of reactive oxygen- and nitrogen species and cell death in the ethylene receptor mutant Never ripe and wild type tomato roots

• Published in: Plant physiology and biochemistry Vol. 97; pp. 313 - 322
• Main Authors: Poór, Péter, Kovács, Judit, Borbély, Péter, Takács, Zoltán, Szepesi, Ágnes, Tari, Irma
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.12.2015
• Subjects: Cell Death - drug effects; DNA Fragmentation - drug effects; Electrolytes - metabolism; Ethylene; Hydrogen Peroxide - metabolism; Lycopersicon esculentum - drug effects; Lycopersicon esculentum - physiology; Mutation - genetics; Never ripe mutant; Nitric Oxide - metabolism; Peroxynitrous Acid - metabolism; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - physiology; Potassium - metabolism; Programmed cell death; Reactive nitrogen forms; Reactive Nitrogen Species - metabolism; Reactive oxygen species; Reactive Oxygen Species - metabolism; Receptors, Cell Surface - metabolism; Salt stress; Sodium - metabolism; Sodium Chloride - pharmacology; Stress, Physiological - drug effects; Superoxides - metabolism; Tomato roots; DHE; NO; Reactive oxygen species; FDA; Reactive nitrogen forms; Tomato roots; DAF-FM DA; DTT; Ethylene; H2DCFDA; STS; SNP; RNS; Programmed cell death; ACC; Salt stress; Nr; E-64; EL; ACO; PCD; ACS; AR; TCA; Never ripe mutant; APF; ROS; ERF; MES; SAM
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2015.10.021

The salt stress triggered by sublethal, 100 mM and lethal, 250 mM NaCl induced ethylene production as well as rapid accumulation of superoxide radical and H2O2 in the root tips of tomato (Solanum lycopersicum cv. Ailsa Craig) wild type and ethylene receptor mutant, Never ripe (Nr/Nr) plants. In the wild type plants superoxide accumulation confined to lethal salt concentration while H2O2 accumulated more efficiently under sublethal salt stress. However, in Nr roots the superoxide production was higher and unexpectedly, H2O2 level was lower than in the wild type under sublethal salt stress. Nitric oxide production increased significantly under sublethal and lethal salt stress in both genotypes especially in mutant plants, while peroxynitrite accumulated significantly under lethal salt stress. Thus, the nitro-oxidative stress may be stronger in Nr roots, which leads to the programmed death of tissues, characterized by the DNA and protein degradation and loss of cell viability under moderate salt stress. In Nr mutants the cell death was induced in the absence of ethylene perception. Although wild type roots could maintain their potassium content under moderate salt stress, K+ level significantly declined leading to small K+/Na+ ratio in Nr roots. Thus Nr mutants were more sensitive to salt stress than the wild type and the viability of root cells decreased significantly under moderate salt stress. These changes can be attributed to a stronger ionic stress due to the K+ loss from the root tissues. •Never ripe gene encodes a mutant ethylene receptor in tomato.•Never ripe mutants are more sensitive to salt stress than the wild types.•The mutants showed higher superoxide and NO accumulation in the root tips.•Root tip cells in Nr plant exhibited programmed cell death at moderate salt stress.•Due to high K+ loss from roots the mutants were subjected to stronger ionic stress.