Photoregulation of Phytochrome Synthesis in Germinating Embryos ofAvena sativaL.

Abstract

Hilton, J. R. and Thomas, B. 1987. Photoregulation of phytochrome synthesis in germinating embryos of Avena sativa L.—J. exp. Bot. 38: 1704–1712. The effect of light on the accumulation of phytochrome in germinating Avena embryos was determined. A quantitative ELISA using monoclonal antibody AFRC MAC 56 was used to measure specifically type 1 (or dark) phytochrome. A pulse of red light given after 14 h imbibition but prior to the onset of type 1 phytochrome synthesis, strongly inhibited subsequent type 1 phytochrome accumulation. This effect of red light at 14 h was reversible by far-red light indicating the involvement of phytochrome. Red light also inhibited phytochrome synthesis after 18 h and 24 h imbibition but after 24 h, far-red light did not reverse the effect. The effect of red light treatment at 18 h was reversed by giving a pulse of far-red light at any time up to 30 h. Seed germination was not influenced by light under the conditions of these experiments. It is proposed that type 2 (or light) phytochrome may be responsible for photoregulation of type 1 phytochrome synthesis in germinating Avena embryos.