XVI International Botanical Congess

Photosynthetic signals profoundly affect the polyribosome association of pea ferredoxin (Fed-1) in transgenic tobacco. This polyribosome association in the light increases Fed-1 mRNA stability and therefore accumulation of Fed-1 mRNA. Fed-1 stability is influenced by a CATT repeat region near the terminus of the 5'UTR by destabilizing nonpolyribsomal mRNA. We are examining this region to determine the features important to Fed-1 light regulation. This precise CATT repeat element is not observed in any other plant mRNAs described so far. To test whether the post-transcriptional mechanism of Fed-1 light regulation applies to other plant genes, we have screened a differentially selected cDNA library and identified a number of Fed-1-like transcripts. We are examining the properties of these genes that influence their accumulation.