title: Deficiency of phytochrome B alleviates chilling-induced photoinhibition in rice.
abstract: OBJECTIVE
  Food crops of tropical origins, such as rice, are often cultivated in areas with suboptimal temperature regimes. The rice phytochrome B-deficient mutant (phyB) is tolerant of chilling temperatures compared with the wild type (WT) under low irradiance, and unsaturated fatty acids (USFAs) of membrane lipids have been shown to play an important role in chilling resistance. However, the relationship between phytochrome B and membrane lipids has not been empirically investigated. •
  
  
  METHODS
  We assessed various photosynthesis indexes in phyB and WT rice: chlorophyll content, maximal photochemical efficiency (Fv/Fm) of photosystem II (PSII), the quantum yield of PSII electron transport (ΦPSII), the percentage of oxidizable P700 (P700), nonphotochemical quenching (NPQ), and the de-epoxidized ratio of xanthophyll cycle (A+Z)/(V+A+Z). We also analyzed the ultrastructure and fatty acid desaturases (FADs) and glycerol-3-phosphate acyltransferase (GPAT) genes of the chloroplasts using transmission electron microscopy and real-time PCR. •
  
  
  RESULTS
  After a chilling treatment of 24 h, chloroplast damage and USFA content reduction were more severe in the WT than in the phyB mutant. Genes involved in the synthesis of USFAs in membranes such as FADs and GPAT were more stable in phyB than in WT. Chlorophyll content, Fv/Fm, ΦPSII, and P700 decreased more slowly under chilling stress and recovered more rapidly under optimal conditions in phyB than in WT. The (A+Z)/(V+A+Z) and NPQ increased more rapidly in phyB than in the WT after 24 h of chilling treatment. •
  
  
  CONCLUSIONS
  Phytochrome B deficiency in rice with more stabilized chloroplast structure and higher USFA content in membrane lipids could alleviate chilling-induced photoinhibition.
authors.affiliation: Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan, Shandong 250014, P. R. China.
authors.forename: Jian-Chao
authors.initials: JC
authors.lastname: Yang
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Xian-Zhi
authors.initials: XZ
authors.lastname: Xie
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Han
authors.forename: Na
authors.initials: N
authors.lastname: Sui
authors.forename: Bao-Shan
authors.initials: BS
authors.lastname: Wang
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000648:ultrastructure*; D003080:Cold Temperature; D004579:Electron Transport; D005227:Fatty Acids / Q000032:analysis; D008027:Light; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects / Q000648:ultrastructure; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology*; D045331:Photosystem I Protein Complex / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000502:physiology; D051939:Phytochrome B / Q000235:genetics* / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D018749:RNA, Plant; D024341:Xanthophylls; D051939:Phytochrome B; D002734:Chlorophyll
keywords: Oryza sativa; chilling stress; photoinhibition; phytochrome B; unsaturated fatty acid; xanthophyll cycle