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Gibberellin‐enhanced transcription by isolated nuclei from cucumber hypocotyls
Author(s) -
Sechley Konrad A.,
Srivastava Lalit M.
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb02945.x
Subject(s) - hypocotyl , transcription (linguistics) , percoll , cucumis , biology , gibberellin , microbiology and biotechnology , rna polymerase ii , transcription factor , biochemistry , in vitro , promoter , botany , gene expression , gene , linguistics , philosophy
Nuclei isolated from apical 1 cm (gibberellin‐responsive region) of dark grown cucumber ( Cucumis sativus L. cv National Pickling) hypocotyls and purified on Percoll step gradients were capable of in vitro transcription; however, only nuclei from the upper regions of the gradient gave GA 4 ‐enhanced transcription. Addition of GA 4 altered the transcriptional activity in favor of RNA polymerase II, from 50% in control to more than 90% in GA 4 ‐treated nuclei. The GA 4 ‐enhanced transcription was rapid and did not require extraction of nuclei in a medium with exogenous GA 4 or preincubation of nuclei in GA 4 . Addition of [ 3 H]GA 4 ‐binding cytosolic protein to nuclei increased the overall transcription but did not affect the GA 4 ‐enhanced transcription. Receptor‐binding assay indicated that these nuclei contain [ 3 H]GA 4 ‐binding sites which are heat‐labile and bound to nuclear matrix. Also, the nuclei seem to contain an inhibitor of GA 4 ‐enhanced transcription which is sensitive to heat and removed by repeated washings. Nuclei from the non‐ responsive basal region of the hypocotyl or from the apical region of cucumber hypocotyls grown at 34°C did not show GA 4 ‐enhanced transcription.