Phytochrome control of levels of mRNA complementary to plastid and nuclear genes of maize.

The involvement of phytochrome in the control of the levels of RNA transcribed from maize plastid and nuclear genes was examined. The effects of illumination with red light, far-red light, or red light followed by far-red light on relative amounts of RNAs complementary to maize plastid genes for the large subunit of ribulose bisphosphate carboxylase (RuBPCase); the 32-kilodalton thylakoid membrane triazine herbicide binding B protein of photosystem II; the alpha, beta, and epsilon subunits of CF(1); subunit III (proton-translocating) of CF(0); the reaction center proteins A1 and A2 of photosystem I; two other light-induced genes for membrane proteins of photosystem II (ORFs 353 and 473); and one gene for an unidentified membrane protein (UORF 443) were measured by hybridization of labeled DNA probes to samples of leaf RNA. Transcripts of two nuclear-encoded genes, the genes for the small subunit of RuBPCase and the light-harvesting chlorophyll a/b binding protein, were studied in the same way. The levels of RNA complementary to all of these light-induced genes were significantly increased within 3 to 6 hours after brief illumination with red light. The stimulatory effects of red light were largely reversed by subsequent illumination with far-red light. It is concluded that phytochrome controls increases in the levels of mRNAs complementary to certain plastid and nuclear genes in dark-grown maize seedlings.