Premium
Fast phototransformation of the 636 nm‐emitting protochlorophyllide form in epicotyls of dark‐grown pea ( Pisum sativum )
Author(s) -
Kósa Annamária,
Márton Zsuzsanna,
Böddi Béla
Publication year - 2005
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2005.00487.x
Subject(s) - protochlorophyllide , pisum , sativum , fluorescence , chemistry , analytical chemistry (journal) , photochemistry , botany , biology , optics , chromatography , physics , biochemistry , biosynthesis , enzyme
The phototransformation of protochlorophyllide forms was studied in epicotyls of dark‐germinated pea ( Pisum sativum L. cv. Zsuzsi) seedlings. Middle segments were illuminated with white or 632.8 nm laser flash or continuous light at room temperature and at −15°C. At low light intensities, photoreduction could be distinguished from bleaching. 77 K fluorescence emission spectra were measured, difference spectra of illuminated and non‐illuminated samples were calculated and/or the spectra were deconvoluted into Gaussian components. The 629 nm‐emitting protochlorophyllide form, P629 (P xxx where xxx is the fluorescence emission maximum), was inactive. For short‐period (2–100 ms) and/or low‐intensity (0.75–1.5 µmol m −2 s −1 ) illumination, particularly with laser light, the transformation of P636 into the 678 nm‐emitting chlorophyllide form, C678 (C xxx where xxx is the fluorescence emission maximum), was characteristic. This process was also found when the samples were cooled to −15°C. The transformation of P644 into C684 usually proceeded in parallel with the process above as a result of the strong overlap of the excitation bands of P636 and P644. The Shibata shift of C684 into a short‐wavelength form, C675–676, was observed. Long‐period (20–600 s) and/or high‐intensity (above 10 µmol m −2 s −1 ) illumination resulted in the parallel transformation of P655 into C692. These results demonstrate that three flash‐photoactive protochlorophyllide forms function in pea epicotyls. As a part of P636 is flash photoactive, its protochlorophyllide molecule must be bound to the active site of a monomer protein unit [Böddi B, Kis‐Petik K, Kaposi AD, Fidy J, Sundqvist C (1998) The two short wavelength protochlorophyllide forms in pea epicotyls are both monomeric. Biochim Biophys Acta 1365: 531–540] of the NADPH:protochlorophyllide oxidoreductase (EC 1.3.1.33). Dynamic interconversions of the protochlorophyllide forms into each other, and their regeneration, were also found, which are summarized in a scheme.