title: Roles of xanthophylls and exogenous ABA in protection against NaCl-induced photodamage in rice (Oryza sativa L) and cabbage (Brassica campestris).
abstract: Changes in actual efficiency of PS II photochemistry, non-photochemical quenching (NPQ), content of xanthophylls and kinetics of de-epoxidation were studied in ABA-fed and non-ABA-fed leaves of rice and cabbage under NaCl stress. Salt stress induced more progressive decrease in actual efficiency of PS II photochemistry (ФPS II), higher reduction state of PS II, and a small significant increase in NPQ in NaCl-sensitive rice plants as compared with NaCl-tolerant cabbage plants, whereas exogenously supplied ABA alleviated the decrease in actual efficiency of PS II photochemistry (ФPS II), induced a lower reduction state of PS II, and caused higher capacity of NPQ in ABA-fed plants than in non-ABA-fed plants. As a result, there were higher activities of photosynthetic electron transport, higher capacity of energy dissipation, and lower cumulation of excess light in cabbage than in rice plants, and in ABA-fed leaves than in non-ABA-fed leaves. The effect of ABA was more efficient in cabbage than in rice plants. Addition of exogenous ABA resulted in enhancement of the size of the xanthophyll cycle pool, promotion of de-epoxidation of the xanthophyll cycle components, and a rise in the level of NPQ by altering the kinetics of de-epoxidation of the xanthophyll cycle. Protection from photodamage appears to be achieved by coordinated contributions by exogenous ABA and xanthophyll cycle-mediated NPQ. This variety of photoprotective mechanisms may be essential for conferring photodamage tolerance under NaCl stress.
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, China.
authors.forename: Su-Qin
authors.initials: SQ
authors.lastname: Zhu
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Chen
authors.forename: Ben-Hua
authors.initials: BH
authors.lastname: Ji
authors.forename: De-Mao
authors.initials: DM
authors.lastname: Jiao
authors.forename: Jian-Sheng
authors.initials: JS
authors.lastname: Liang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology*; D001937:Brassica / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D006207:Half-Life; D007700:Kinetics; D008027:Light; D012275:Oryza / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D055668:Photochemical Processes / Q000187:drug effects / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D020011:Protective Agents / Q000494:pharmacology*; D012965:Sodium Chloride / Q000633:toxicity*; D024341:Xanthophylls / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D020011:Protective Agents; D024341:Xanthophylls; D012965:Sodium Chloride; D000040:Abscisic Acid