cDNA cloning of a tetraubiquitin gene, and expression of ubiquitin-containing transcripts, in aleurone layers of Avena fatua.

A lambda gt 11 cDNA library, constructed from poly(A)+ mRNA isolated from Avena fatua aleurone layers incubated with 1 microM gibberellin A1 (GA1) for 4 days, was screened with an anti-idiotypic antiserum raised against the GA-specific monoclonal antibody MAC 182. One positive clone was isolated, sequenced and shown to encode a tetraubiquitin based on the deduced amino acid sequence. This polyubiquitin cDNA exhibited a high degree of homology to a cloned wheat hexaubiquitin in its 3'-non-coding region. Analysis of total RNA isolated from A. fatua aleurone layers, treated without or with a range of concentrations of GA1 from 10(-11) to 10(-6) M, by northern blotting using the cDNA probe revealed 8 different ubiquitin-containing transcript classes all of which are constitutively expressed in aleurone and are regulated by GA1.