Increased tolerance to salt stress in OPDA-deficient rice ALLENE OXIDE CYCLASE mutants is linked to an increased ROS-scavenging activity

• Published in: Journal of experimental botany 2015-06, Vol.66 (11), p.3339-3352
• Main Authors: Hazman, Mohamed, Hause, Bettina, Eiche, Elisabeth, Nick, Peter, Riemann, Michael
• Format: Article
• Language: English
• Subjects: Abscisic Acid - metabolism; Cyclopentanes - metabolism; Fatty Acids, Unsaturated - metabolism; Gene Expression Regulation, Plant; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Intramolecular Oxidoreductases - genetics; Intramolecular Oxidoreductases - metabolism; Isoleucine - analogs & derivatives; Isoleucine - metabolism; Lipid Peroxidation; Oryza - drug effects; Oryza - enzymology; Oryza - genetics; Oryza - physiology; Oxylipins - metabolism; Plant Growth Regulators - metabolism; Plant Leaves - drug effects; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - enzymology; Plant Roots - genetics; Plant Roots - physiology; Reactive Oxygen Species - metabolism; RESEARCH PAPER; Seedlings - drug effects; Seedlings - enzymology; Seedlings - genetics; Seedlings - physiology; Sodium Chloride - pharmacology; Stress, Physiological
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erv142

Salinity stress represents a global constraint for rice, the most important staple food worldwide. Therefore the role of the central stress signal jasmonate for the salt response was analysed in rice comparing the responses to salt stress for two jasmonic acid (JA) biosynthesis rice mutants (cpm2 and hebiba) impaired in the function of ALLENE OXIDE CYCLASE (AOC) and their wild type. The aoc mutants were less sensitive to salt stress. Interestingly, both mutants accumulated smaller amounts of Na⁺ ions in their leaves, and showed better scavenging of reactive oxygen species (ROS) under salt stress. Leaves of the wild type and JA mutants accumulated similar levels of abscisic acid (ABA) under stress conditions, and the levels of JA and its amino acid conjugate, JA–isoleucine (JA-Ile), showed only subtle alterations in the wild type. In contrast, the wild type responded to salt stress by strong induction of the JA precursor 12-oxophytodienoic acid (OPDA), which was not observed in the mutants. Transcript levels of representative salinityinduced genes were induced less in the JA mutants. The absence of 12-OPDA in the mutants correlated not only with a generally increased ROS-scavenging activity, but also with the higher activity of specific enzymes in the antioxidative pathway, such as glutathione S-transferase, and fewer symptoms of damage as, for example, indicated by lower levels of malondialdehyde. The data are interpreted in a model where the absence of OPDA enhanced the antioxidative power in mutant leaves.