title: Cytokinin dehydrogenase differentially regulates cytokinin and indirectly affects hydrogen peroxide accumulation in tomato leaf.
abstract: Cytokinin dehydrogenase (CKX) catalyzes the irreversible degradation of cytokinins (CKs). CKs play a role in the regulation of hydrogen peroxide (H(2)O(2)) accumulation while H(2)O(2) is involved in chlorophyll degradation. Here, we elucidated how CKX differentially regulates representative CK levels and indirectly influence H(2)O(2) accumulation in tomato leaves. We induced drought, salt and iron-deficiency stresses in tomato plants and found that chlorosis-inducing stresses (salt and iron-deficiency) induced lower chlorophyll levels as compared to drought stress and control. Protein gel blot analysis detected two CKXs in tomato leaves: a 35 kDa protein (CKX35) found in chlorotic leaves associated with a reduction in representative CK levels and high H(2)O(2) concentrations, and a 37 kDa protein (CKX37) found in green leaves associated with representative CKs and H(2)O(2) at normal levels. In summary, CKX isoforms in the tomato leaf appear to have distinct roles in differentially regulating CK levels and indirectly influencing H(2)O(2) accumulation.
authors.affiliation: Department of Molecular and Cellular Biology, Graduate School of Medical Sciences, Nagoya City University, Aichi 467-8601, Japan.
authors.forename: Marni E
authors.initials: ME
authors.lastname: Cueno
authors.forename: Kenichi
authors.initials: K
authors.lastname: Imai
authors.forename: Kuniyasu
authors.initials: K
authors.lastname: Ochiai
authors.forename: Takashi
authors.initials: T
authors.lastname: Okamoto
mesh_terms: D003583:Cytokinins / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D003583:Cytokinins; D010937:Plant Growth Regulators; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C019984:cytokinin oxidase