title: Genotypic variation of Rubisco expression, photosynthetic electron flow and antioxidant metabolism in the chloroplasts of chill-exposed cucumber plants.
abstract: Genetic improvement of agronomic crops is necessary to cope with chilling stress. To identify the physiological factors responsible for this genotypic difference in chill-induced inhibition of photosynthesis, leaf CO2 assimilation, the electron flux in the chloroplast and the antioxidant metabolism in isolated chloroplasts were examined in two genotypes of cucumber (Cucumis sativus) plants with distinct chilling tolerance. Cucumber plants were exposed to 100 micromol m(-2) s(-1) at 9/7 degrees C (day/night) for 10 d and were then returned to optimal conditions for 2 d. Chilling resulted in more significant reductions in rbcL and rbcS transcripts, ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) content and initial Rubisco activity, leading to higher electron flux to O2 in the chilling-sensitive genotype than in the chilling-tolerant genotype. The chilling-tolerant genotype showed lower H2O2 contents in the chloroplasts by maintaining higher H2O2-scavenging activity in the chloroplasts than in the chilling-sensitive genotype. H2O2 accumulation in chloroplast was negatively correlated with the initial Rubisco activity and photosynthetic rate.
authors.affiliation: Department of Horticulture, Huajiachi Campus, Zhejiang University, Kaixuan Road 268, Hangzhou 310029, PR China.
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Mao
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Huang
authors.forename: Xing-Shun
authors.initials: XS
authors.lastname: Song
authors.forename: Salvador
authors.initials: S
authors.lastname: Nogués
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D015152:Blotting, Northern; D002245:Carbon Dioxide / Q000378:metabolism; D002736:Chloroplasts / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D018553:Cucumis sativus / Q000235:genetics / Q000378:metabolism*; D004583:Electrons; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D006861:Hydrogen Peroxide / Q000032:analysis; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012273:Ribulose-Bisphosphate Carboxylase / Q000032:analysis / Q000235:genetics* / Q000502:physiology
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D002245:Carbon Dioxide; D006861:Hydrogen Peroxide; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen