Phototransformations of Phytochrome

Strict requirement of fluctuating temperatures as a reliable gap signal in Picris hieracioides var. japonica seed germination

“…Therefore, the decline in the R/FR ratio is mainly controlled by the leaf canopy, and not the soil profile. When the inactive form of phytochrome (P r ) absorbs R light, which generally stimulates germination, it is transformed to the active form (P fr ); in contrast, when P fr absorbs FR light, it is transformed to P r (Kendrick and Spruit 1977). Light brings about a ''photoequilibrium'' in the ratio of P fr /P total (i.e., active form/total phytochrome: u; Bewley and Black 1994).…”

Phytochrome A-mediated inhibition of seed germination in tomato

“…The photoreceptor operating in the ®rst phase is considered to be phy in the form of Pfr or an intermediate of Pr/Pfr photoconversion, which was formed and dehydrated in the seed during the maturing process on the mother plant (Frankland and Taylorson 1983). The photoconversion intermediate generates Pfr during imbibition (Kendrick and Spruit 1977).…”

A Novel Photoactive GAF Domain of Cyanobacteriochrome AnPixJ That Shows Reversible Green/Red Photoconversion

“…Lumi-R, which is the photoconversion intermediate formed from the photoexcited Pr in the nanosecond time range, has a weak 10-nm to 20-nm red-shifted peak relative to that of Pr. 28,29 APi 680 also had a weak 30-nm red-shifted peak relative to that of APr 648 and was stable up to 100 ns. The spectral similarity of APi 680 and lumi-R of Phys might indicate that the photoconversion of APr 648 into APg 543 begins with the initial photoreaction of a Z-to-E isomerization of the C15fC16 bond, as has been proposed for lumi-R of Phys.…”

“…The APi 680 -to-APi 610 conversion, which was stable up to 100 μs, accompanied the 70-nm blue shift of the peak wavelength, whereas the conversion from lumi-R to the second intermediate meta-Ra accompanied only the 25-nm blue shift that occurred in the period of microsecond order. 28 It has been suggested that the conversion of lumi-R into meta-Ra accompanies structural relaxation at the chromophore-binding site, although the precise reaction has not been established. 32 Thus, the underlying mechanisms of the second conversion process might also be similar between these two proteins.…”