GIBBERELLIN-STIMULATED CHANGES IN ABUNDANCE OF 2 MESSENGER-RNAS IN THE DEVELOPING SHOOT OF DWARF PEAS (PISUM-SATIVUM L)

Changes in gene expression followed the application of exogenous gibberellin (GA) to dwarf peas, as demonstrated by increases in abundance of a small population of mRNAs. The nature of these changes was investigated by isolating two cDNA clones. The clones were selected by differential screening of a lambda gt10 cDNA library derived from mRNA that had been extracted from GA-treated dwarf peas. Characterization of the two clones included sequencing and Northern blot hybridizations to compare dwarf and tall pea RNAs. Transcripts with homology to these clones were expressed in both dwarf and tall peas. Northern blotting of mRNAs isolated from 1 to 48 h after GA application revealed a differential expression of the relevant genes. Differences in amounts of RNA at several sampling times between 1 and 48 h were also observed in the dwarf and tall plants. Southern blot hybridizations, using genomic DNA digests with three restriction enzymes, indicated the likelihood that a single gene is represented by one of the cDNAs, and one or more genes by the other cDNA. The hybridizations with the genomic DNA fragments were identical in the dwarf and tall phenotypes for each of the cDNAs.