Abstract
The expression of two cytokinin-repressed genes, CR9 and CR20, was investigated in cucumber (Cucumis sativus L.). In excised cotyledons, the level of the CR20 transcript markedly decreased in the early periods of treatment with N6-benzyladenine (BA), i.e. well before BA-induced expansion of cotyledons was observed. The repression of CR20 was BA-dose dependent and highly specific for cytokinins. These features were similar to those of CR9 reported previously (H. Teramoto et al., 1994, Planta 193, 573–579). Furthermore, levels of the CR9 and CR20 transcripts decreased during the early phase of greening and soon after wounding of cotyledons. The levels were much lower in young leaves than in mature or senescent leaves. Because cytokinins are thought to control greening and aging of leaves, and to mediate response to wounding, the expression of these two genes could be closely related to the action of such hormones. However, there were some differences between the expression of CR9 and CR20, i.e. the pattern of diurnal changes and the transcript levels in roots. Therefore, some other factors in addition to cytokinins appear to differentially affect the expression of these two genes. Several transcripts of CR20 of different lengths (0.8–2.3 kb) were detected by Northern blot analysis. No long open reading frames could be detected in two CR20 cDNAs with different structures.
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Abbreviations
- BA:
-
benzyladenine
- 16 L/8 D:
-
cycle of 16 h light and 8 h darkness
References
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The authors are grateful for access to the facilities of the Laboratory of Radioisotopes at Kyoto Prefectural University, during the radiolabeling experiments performed in this study.
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Teramoto, H., Toyama, T., Takeba, G. et al. Changes in expression of two cytokinin-repressed genes, CR9 and CR20, in relation to aging, greening and wounding in cucumber. Planta 196, 387–395 (1995). https://doi.org/10.1007/BF00201400
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DOI: https://doi.org/10.1007/BF00201400