Ginkgo biloba L. is a large tree native in China with evolutionary affinities to the conifers and cycads. However unlike conifers, the gymnosperm G. biloba is not able to synthesize chlorophyll (Chl) in the dark, in spite of the presence of genes encoding subunits of light-independent protochlorophyllide oxidoreductase (DPOR) in the plastid genome. The principal aims of the present study were to investigate the presence of DPOR protein subunits (ChlL, ChlN, ChlB) as well as the key regulatory step in Chl formation: aminolevulinic acid (ALA) synthesis and abundance of the key regulatory enzyme in its synthesis: glutamyl-tRNA reductase (GluTR). In addition, functional stage of photosynthetic apparatus and assembly of pigment-protein complexes were investigated. Dark-grown, illuminated and circadian-grown G. biloba seedlings were used in our experiments. Our results clearly showed that no protein subunits of DPOR were detected irrespective of light conditions, what is consistent with the absence of Chl and Chl-binding proteins (D1, LHCI, LHCIIb) in the dark. This correlates with low ALA-synthesizing capacity and low amount of GluTR. The concentration of protochlorophyllide (Pchlide) in the dark is low and non-photoactive form (Pchlide633) was predominant. Plastids were developed as typical etioplasts with prollamelar body and few prothylakoid membranes. Continual illumination (24 h) only slightly stimulated ALA and Chl synthesis, although Pchlide content was reduced. Prollamelar bodies disappeared, but no grana were formed, what was consistent with the absence of D1, LHCI, LHCIIb proteins. Lightinduced development of photosynthetic apparatus is extremely slow, as indicated by Chl fluorescence and gas exchange measurements. Even after 72 h of continuous illumination, the values of maximum (Fv/Fm) and effective quantum yield (ΦPSII) and rate of net photosynthesis (PN) did not reach the values comparable with circadian-grown plants. and A. Pavlovič ... [et al.].
In contrast to angiosperms, which accumulate protochlorophyllide after application of aminolevulinic acid in the dark, feeding with aminolevulinic acid (0.01-20 mM) via the roots in the 18-d-old seedlings of Norway spruce (Picea abies) stimulated not only protochlorophyllide but also chlorophyll accumulation. and A. Pavlovič ... [et al.].
Life and research results of Pavel Siffel, a talented but untimely deceased Czech scientist in photosynthesis, are reviewed. He studied biophysics and physiology of chlorophyll, its complexes with proteins, their absorption and fluorescence spectra, activities in mutants and transformants, dealt with chlorophyll biosynthesis and protochlorophyllide photoreduction, pigments in plants grown at CO2 deficiency and under simulated acid rain, with changes accompanying leaf and plant development, photobleaching, etc. He participated in construction of specialised spectrofluorometers, finally he built the kinetic spectrophotometer SpeKin. and J. Květoň ... [et al.].