期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：12
页码：5207-5211
DOI：10.1073/pnas.88.12.5207
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have examined the biological activity of rice type I phytochrome (PI) in transgenic tobacco seedlings. The progeny of four independent transformants that expressed the rice PI gene segregated 3:1 for shorter hypocotyl length under dim white light (0.04 W/m2). By contrast, this phenotype was not observed either in the dark or under white light at higher intensity (6.0 W/m2). This suggests that the phenotype is dependent not only on light but also on light intensity. The increased light sensitivity cosegregated with the kanamycin-resistance marker as well as with the rice PI polypeptides, indicating that this phenotype is directly related to the expression of the transgene. The transgenic plants showing short hypocotyls exhibited a reduced growth rate throughout the elongation period, and the resulting shorter hypocotyl length was attributable to shorter epidermal cell length but not to reduced cell number. Furthermore, successive pulse irradiations with red light elicited short hypocotyls similar to those obtained under dim white light, and the effect was reversed by immediate far-red light treatment, providing a direct indication that the phenotype is caused by biologically active rice PI. Therefore, the far-red-absorbing form of the introduced rice PI appears to regulate the hypocotyl length of the transgenic tobacco plants through endogenous signal-transduction pathways. This assay system will be a powerful tool for testing the biological activity of introduced phytochrome molecules.
