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Plant Physiology 95:443-449 (1991) © 1991 American Society of Plant Biologists Effect of Temperature Conditioning on Chilling Injury of Cucumber CotyledonsPossible Role of Abscisic Acid and Heat Shock ProteinsDepartment of Vegetable Crops, University of California, Davis, California 95616, Department of Agronomy and Range Science, University of California, Davis, California 95616
Endogenous abscisic acid levels and induced heat shock proteins were measured in tissue exposed for 6 hours to temperatures that reduced their subsequent chilling sensitivity. One-centimeter discs excised from fully expanded cotyledons of 11-day-old seedlings of cucumber (Cucumis sativus L., cv Poinsett 76) were exposed to 12.5 or 37°C for 6 hours followed by 4 days at 2.5 or 12.5°C. Ion leakage, a qualitative indicator of chilling injury, increased after 2 to 3 day exposure to 2.5°C, but not to 12.5°C, a nonchilling temperature. Exposure to 37°C before chilling significantly reduced the rate of ion leakage by about 60% compared to tissue exposed to 12.5°C before chilling, but slightly increased leakage compared to tissue exposed to 12.5 or 37°C and held at the nonchilling temperature of 12.5°C. There was no relationship between abscisic acid content following exposure to 12.5 or 37°C and chilling tolerance. Five heat shock proteins, with apparent molecular mass of 25, 38, 50, 70, and 80 kilodaltons, were induced by exposure to 37 or 42°C for 6 hours, and their appearance coincided with increased chilling resistance. Heat shock treatments reduced the synthesis of three proteins with apparent molecular mass of 14, 17, and 43 kilodaltons. Induction of heat shock proteins could be a possible cause of reduced chilling injury in tissue exposed to 37 or 42°C.
1 Present address: Instituto de Agroquímica y Tecnología de Alimentos. C.S.I.C., C/Jaime Roig 11, 46010 Valencia, Spain. Financial support was provided by a grant from Generalitat Valenciana Conselleria de Cultura, Educació i Ciència. 2 Present address: Departamento de Bioquímica Vegetal. Estación Experimental del Zaidin. C.S.I.C., 18008 Granada, Spain. 3 Present address: Department of Plant Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5. This article has been cited by other articles:
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