Organ-specific nuclear RNAs in tobacco.

Abstract

The developmental regulation of nuclear RNA sequences in tobacco vegetative (leaf, root, stem) and floral (petal, ovary, anther) organ systems was studied using RNA-excess-single-copy DNA hybridization reactions. Eighteen percent of the single copy DNA, equivalent to 1.1 .times. 105 kilobases (kb) of diverse transcripts, is represented in the nuclear RNA of each organ. Each nuclear RNA population has both shared and organ-specific sequences. Depending upon the nuclear RNA, 10-40% of the complexity, or 1.1-4.4 .times. 104 kb of diverse sequence, is organ-specific. Collectively, at least 45% of the single-copy DNA, or 3 .times. 105 kb, is represented in the nuclear RNA of the entire plant. Hybridization experiments with polysomal RNA showed that organ-specific mRNA are present in both the unique and shared nuclear RNA subsets. Tobacco nuclear RNA sequences are under striking developmental control. Both transcriptional and post-transcriptional processes play a role in regulating plant gene expression.