Interaction Between Cryptochrome and Phytochrome in Higher Plant Photomorphogenesis

Abstract

At least three photoreceptors are involved in the mediation of light action in higher plant photomorphogenesis: cryptochrome (UV‐A/blue light photoreceptor), UV‐B photoreceptor, and phytochrome. The degree of photoreceptor interaction in photomorphogenesis can apparently vary depending on the response, the species, and the stage of development of the biological system. In most cases of interaction studied so far, Pfr, the physiologically active form of phytochrome, is apparently required for the final expression of the response. In some systems, the cryptochrome and/or UV‐B photoreceptor mediated action of UV/blue radiation is required to establish/enhance/maintain responsiveness toward Pfr. There is no evidence for photoreceptor interaction in some response‐system combinations. It is not known for sure if this apparent lack of photoreceptor interaction represents a real situation or just a failure to detect it because of experimental limitations. Practically nothing is known about the mechanism of photoreceptor interaction at the molecular level.

Characterisation of the interaction between cryptochromes and phytochromes in blue light‐induced coiling and prehaustoria development of dodder (Cuscuta campestris) seedlings

“…To characterise cryptochromes and their interaction with phytochrome responses, several light and chemical treatments are described below (See Bartels & Hyde, 1970;Gaba & Black, 1987;Gardner & Gorton, 1985;Hilton et al, 1969;Mancinelli, 1989;Mohr, 1984Mohr, , 1987Sponga et al, 1986).…”

Light effects on in vitro rooting of pear cultivars of different rhizogenic ability

“…A 12-h FR-pretreatment of shoots before being placed in darkness was done to transform the physiologically active Pfr into the inactive species Pr (Mohr, 1972). The calculated phytochrome photoequilibrium values (Mancinelli 1989) were 0.004 for FR, 0.4 for B, 0.7 for W and 0.8 for R. Blue light was produced by filtering the same light source through a Lee 141 cinemoid filter (Lee Filters LTD, Hants, UK), while red light was produced via a Lee 106 filter.…”

Cryptochrome, Phytochrome, and Anthocyanin Production

“…The unknown nature of the UV-B-photoreceptor and cryptochrome and the fact that UV and BL excite not only these two photoreceptors, but also phytochrome, complicate studies on photoreceptor involvement and interaction in the mediation of responses to UV and BL (7,14). The selection of light treatments that can be used to discriminate the action of different photoreceptors is based on criteria ( 18,24) that take into account the differences between the known (phytochrome) and the inferred (cryptochrome and UV-B-photoreceptor) spectral properties of the photoreceptors.…”

“…The extent of the response is a function of light quality, fluence rate, and exposure duration; action peaks have been found in the UV, BL,3 R, and FR spectral regions. The relative efficiencies of these regions vary significantly, depending on the species and experimental conditions (10,11).Anthocyanin production and other plant photomorphogenic responses to prolonged R and FR irradiations are mediated by phytochrome (10,11,16 acting or acting independently of one another (2,7,(19)(20)(21)24).The unknown nature of the UV-B-photoreceptor and cryptochrome and the fact that UV and BL excite not only these two photoreceptors, but also phytochrome, complicate studies on photoreceptor involvement and interaction in the mediation of responses to UV and BL (7,14). The selection of light treatments that can be used to discriminate the action of different photoreceptors is based on criteria ( 18,24) that take into account the differences between the known (phytochrome) and the inferred (cryptochrome and UV-B-photoreceptor) spectral properties of the photoreceptors.…”