Abstract:

【Objective】 The purpose of this project was to separate protein spots induced by low temperature in cucumber leaves of two genotypes, and reveal the mechanism of cucumber responding to low temperature. 【Method】Two cucumber genotypes (Cucumis sativus L. cv Xintaimici and Jinyan 4) were both treated with low temperature (15/15℃) and normal temperature (25/18℃) under the light of 100 μmol?m-2?s-1 for 7 d to study the changes of leaf proteome. The total proteins were extracted by three-steps, separated by two-dimensional gel electrophoresis (2-DE) and analysed through MALDI-TOF mass spectrometry. 【Result】 SDS-PAGE showed that few proteins were extracted by hydrophilic solutionⅠ. The extracts of solution Ⅱand Ⅲ were separated through 2-DE. Compared with treatment of normal temperature, low temperature made ‘Xintaimici’ genotype to produce 7 special protein spots, 2 up-regulated protein spots, 2 down-regulated protein spots and 5 unexpressed protein spots, and allowed ‘Jinyan 4’ to produce 7 special protein spots, 1 up-regulated protein spot, 4 down-regulated protein spots and 9 unexpressed protein spots. Three special protein spots, which were highly expressed under low temperature, were identified to be the large subunit of ribulose 1,5-bisphosphate carboxylase. 【Conclusion】There were few hydrophilic proteins in cucumber leaves. Low temperature influenced leaf proteome in two cucumber genotypes and different cultivars expressed different proteins. Ribulose 1,5-bisphosphate carboxylase may be related to low-temperature tolerance in cucumber leaves.

Key words: Cucumis sativus L., proteome, low temperature, 2-DE, MALDI-TOF-MS, ribulose 1, 5-bisphosphate carboxylase