title: Timing of the initial action of phytochrome with regard to protochlorophyll synthesis in the mustard seedling.
abstract: Significant accumulation of photoconvertible protochlorophyll(ide) in the cotyledons of the mustard seedling takes place from 24 h after sowing onwards (25° C). The rate of accumulation in darkness is greatly increased by a pretreatment with red or far-red light. The strong effect of continuous red light, given from the time of sowing, remains fully reversible by a 756 nm-light pulse up to about 18 h after sowing. On the other hand, the effect of continuous far-red light which can be detected at 15 h after sowing is not influenced by a subsequent application of 756 nm-light pulses. An interpretation of the data requires the concept that continuous red light and continuous far-red light act from different sites. This conclusion is based on a comparison of the present data with the earlier published data on phytochromemediated anthocyanin synthesis in the mustard seedling cotyledons.
authors.affiliation: Biologisches Institut II, Universität Freiburg i.Br., Schänziestraße 9, D-7800, Freiburg i.Br., Federal Republic of Germany.
authors.forename: H
authors.initials: H
authors.lastname: Kasemir
authors.forename: P
authors.initials: P
authors.lastname: Huber
authors.forename: H
authors.initials: H
authors.lastname: Mohr