title: [Thermal dissipation pathway in cucumber seedling leaves under hypoxia stress].
abstract: A water culture experiment was conducted to study the relationship between photosynthetic thermal dissipation and xanthophyll cycle in cucumber seedling leaves under hypoxia stress (the dissolved oxygen concentration in nutrient solution was 0.9-1.1 mg x L(-1)). Under the hypoxia stress, there was a significant decrease in the quantum yield of PS II photochemistry rate (phi(PS II)), net photosynthetic rate (Pn) under saturation light intensity, quanta yield (AQY), and maximal photochemical efficiency (Fv/Fm), suggesting that the photoinhibition of the seedling leaves was induced. Meanwhile, the thermal dissipation (NPQ) and the allocation of dissipation energy (D) by antenna increased, but the photochemical quenching apparent (q(p)) decreased, suggesting the enhancement of thermal dissipation in cucumber leaves under hypoxia stress. A positive correlation was observed between NPQ and xanthophyll de-epoxidation state (DEPS), and both of them were promoted by ascorbic acid (AsA) and inhibited by 1,4-dithiothreitol (DTT), suggesting that xanthophyll cycle was the major pathway of photosynthetic thermal dissipation in cucumber seedling leaves under hypoxia stress.
authors.affiliation: College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China. yongxiajia@163.com
authors.forename: Yong-xi
authors.initials: YX
authors.lastname: Jia
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Li-ping
authors.initials: LP
authors.lastname: Wang
authors.forename: Sheng
authors.initials: S
authors.lastname: Shu
authors.forename: Shi-rong
authors.initials: SR
authors.lastname: Guo
mesh_terms: D018553:Cucumis sativus / Q000378:metabolism / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000502:physiology; D018526:Plant Transpiration; D036226:Seedlings / Q000378:metabolism / Q000502:physiology*; D013312:Stress, Physiological; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D010100:Oxygen