Abstract:

【Objective】 To investigate the potential effects of sucrose on floral induction of tobacco, the contents and transportations of sucrose in different tissues were studied in tobacco treated with low temperature. 【Method】 After treatment with 4℃ for 24 h, the sucrose and H2O2 contents, the gene expression levels and activities of SPS and SUT1, and the redox states of ascorbate pool in different tissues of tobacco were analyzed in treated and control plants. 【Result】 In low temperature treated plants, sucrose contents increased gradually in leaves, petioles, stems and apical meristem. The activities of SPS increased and that of amylase decreased, respectively, and starch contents increased in leaves. The up-regulated expressions of SPSC in leaves and SUT1 in lateral vein were found. Moreover, the increased H2O2 contents, the tendency for ascorbate to oxidize in lateral vein, petiole, stem and apical meristem were also observed. 【Conclusion】 The results suggested that the sucrose transportation from leaves to apical meristem was enhanced by low temperature, resulting from the stimulated loading and unloading of SUT1 in phloem by the oxidation tendency in cytosolic circumstance.

Key words: tobacco, low temperature, sucrose transportation, gene expression, apical meristem