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Fluorescence Analysis of Oat phyA Deletion Mutants Expressed in Tobacco Suggests that the N‐Terminal Domain Determines the Photochemical and Spectroscopic Distinctions between phyA′ and phyA″†
Author(s) -
Sineshchekov Vitally A.,
Clough Richard C.,
JordanBeebe Emily T.,
Vierstra Richard D.
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb03354.x
Subject(s) - phytochrome a , phytochrome , etiolation , fluorescence , mutant , chemistry , biophysics , photochemistry , biology , biochemistry , red light , botany , gene , optics , physics , arabidopsis thaliana , enzyme
— In vivo low‐temperature (85 K) fluorescence spectroscopy has defined two phytochrome A (phyA) subpopulations, designated phyA′ and phyA″, in etiolated seedlings (V. A. Sineshchekov, J. Photochem. Photobiol. 28, 53–55, 1995). Phytochrome A' is the more abundant but light‐labile species characterized by longer wavelength emission/absorption maxima (687/673 nm) and by a higher extent of the photoconversion of its red‐absorbing form (Pr) into photoproduct (lumi‐R) at 85 K (γ 1 ≈ 0.5). Phytochrome A″ is the minor but relatively light‐stable species, characterized by shorter wavelength maxima (682/668 nm) and by a lower γ 1 (<0.05). To help define domains within phyA responsible for these differences, the low‐temperature spectral properties of transgenic tobacco expressing full‐length (FL) oat phyA and C‐and N‐terminally truncated versions (CD [Δ786–1129] and NA [Δ7–69], respectively) were compared. Oat phytochrome expression was more pronounced than that of tobacco in the basal section of etiolated seedlings following 2 h irradiation with white light. Seedlings expressing FL and CD phyA had spectral properties for phyA′ and phyA″ that were indistinguishable from that of wild‐type tobacco. Conversely, expression of NA phyA generated an abundant phy species that behaved like phyA″. From this we conclude that the N‐terminal domain of phyA is involved in determining the photochemical and spectroscopic distinctions between the native phyA′ and phyA″ species.