ABUNDANCE AND HALF-LIFE OF THE DISTINCT OAT PHYTOCHROME A3 AND A4 MESSENGER-RNAS

Gene-preferential oligonucleotide probes were used to determined the r elative abundance and half-lives of distinct oat phytochrome A (PHYA) mRNAs. Oat PHYA mRNAs are highly conserved in the 5'-untranslated regi on and the coding region, but the 3'-untranslated region has an overal l lower sequence conservation and was the source of gene-preferential probes. PHYA3 mRNA was estimated to be ca. 61% of the oat PHYA mRNA po ol present in poly(A)(+) RNA from dark-grown seedlings. The half-lives for PHYA3 and PHYA4 mRNAs were both estimated to be ca. 30 min, and a similar short half-life was estimated for the average PHYA mRNA. Sequ ence comparisons of PHYA mRNAs from four grass species identified cons erved sequences within the 5'- and 3'-untranslated regions that might be important for PHYA mRNA degradation.