Dark Reversion of Phytochrome in Sinapis alba L.

Phytochrome in Sinapis alba L. (white mustard) seedlings undergoes both decay and reversion after an exposure to red light. This is typical of other crucifers and of dicotyledons in general. In the presence of sodium azide, decay is inhibited, and reversion continues at about the same rate as in buffer alone. The reversion has been demonstrated both in cotyledon plus hypocotyl hook and in hypocotyl hook samples alone and is of the same order of magnitude in both. Contrary conclusions in the literature that there is no reversion in Sinapis are based on indirect measurements and are unjustified.