Fluorescence spectroscopy and photochemistry of phytochromes A and B in wild-type, mutant and transgenic strains of Arabidopsis thaliana

Missense Mutation in the PAS2 Domain of Phytochrome A Impairs Subnuclear Localization and a Subset of Responses

“…Fluorescence data were obtained as described in Sineshchekov et al (1998) from 3-to 4-day-old seedlings grown in complete darkness at 26ЊC on filter paper moistened with tap water. The cotyledons were cut off to eliminate protochlorophyllide interference, and 10 hypocotyls plus roots were glued with a 50:50 water:glycerol mixture to a Plexiglas plate of the sample holder.…”

phyA-GFP is spectroscopically and photochemically similar to phyA and comprises both its native types, phyA’ and phyA”

“…This shift is characteristic of the other investigated Arabidopsis phyA overexpressors. 48 The fact that phyA-GFP has two phyA forms similar to those of the native phyA suggests that the phyA-GFP fusion protein also undergoes the post-translational modification proposed for the native phyA. 53 This observation shows that either of the two phyA pools can participate in the nuclear-cytoplasmic partitioning of the receptor and thus, of the phyA signal transduction.…”

“…In the case of tobacco samples, the background spectrum was taken from the root tissues at its base after Pr conversion into Pfr upon red illumination, which practically coincides with the spectrum of the phyA mutants of Arabidopsis. 48 After its subtraction from the experimental spectra, we obtained the spectra of the phytochrome, and from them, a number of parameters describing the pigment in its native state in the cell. These are (1) spectroscopic characteristics ( position, λ max , shape and half-band width, Δλ, of the spectrum); (2) total phytochrome content (P tot in relative units, RU) proportional to the fluorescence intensity related to the intensity of the background fluorescence at 660 nm reflecting the mass of the plant tissue in the sample under the exciting light beam, P tot = F 0 /F b ; and (3) extent of the Pr→lumi-R conversion at 85 K to reach a photoequilibrium, γ 1 = (F 0 − F 1 )/F 0 .…”

Two modes of the light-induced phytochrome A decline – with and without changes in the proportion of its isoforms (phyA′ and phyA″): evidence from fluorescence investigations of mutant phyA-3D pea

“…The experimental approach was the same as that used earlier (see [11][12][13][14]17,18,21,22] and the literature cited therein). To obtain the phytochrome parameters in the sample, low-temperature (85 K) emission spectra (wavelength of the excitation, k e , 610 or 650 nm) were taken under two different experimental settings (see Figs.…”

“…With the use of in situ low-temperature fluorescence spectroscopy, two phyA native species, phyA 0 and phyA 00 , were found in experiments on phyBdeficient mutants (of cucumber [11], Arabidopsis [12] and pea [13]) and on roots of the wild type tobacco, which according to [6] contains almost no phyB (V. Sineshchekov, unpublished results). The most pronounced phenomenological difference of the two phyA species, which allows their quantitative assay in plant tissues, is high and low extent (c 1 ) of the Pr conversion into the first photoproduct, lumi-R, %0.5 for phyA 0 and %0.05 for phyA 00 (Pr 0 and Pr 00 phenomenological types, respectively).…”