Etiolated leaves

Fig 7.1(a) The diamond (D-) membrane system of the FLB in etiolated leaves. Projection of a section cut approximately normal to the jlOO) plane. The lower mserts show the match between the experimental micrograph and the computer generated constant mean curvature PCS projections for two different distances along the [100] direction. The upper inserts show the Fourier transform (calculated for the regions indicated) for the corresponding experimental and theoretical projections (a and b, and a and b, respectively). 

Figure 7.1(b) The diamond (D-) membrane system of the PLB in etiolated leaves. Projection along the [110] direction simulated. The corresponding simulated projection is overlayed (right) on two regions with different direction. The Fourier transform calculated for the region indicated is also shown (experiment left, calculation right). 

Figure 2 (B) shows thermoluminescence bands generated by mature wheat leaves [curves (a) and (b)] and by greening wheat leaves grown under intermittent illumination [curves (c) and (d)]. The continuous curves are for materials illuminated for I minute at -60 °C [curves (a) and (c)], and at-20 °C [curves (b) and (d)] the dashed curves are for the same materials without prior illumination. Each thermoluminescence band has its own (approximate) emission temperature Zy band( -45 °C where the subscript V stands for variable location ofthe band), A-band (-10 °C), B,-band (25 °C), B2-band (40 °C) and C-band (+55 °C). The C band is the major emission band in etiolated leaves [solid curves in (c) and (d)] and is apparently unaffected by prior actinic illumination [dashed curves in (c) and (d)]. Illumination of fully greened, mature leaves at -60 °C produces a weak Zy-band at -45 °C, a weakened C-band at 55 °C, a strong composite B-band, with Bi-band at 20 °C and B2-band shoulder at 40 °C, which together form the composite B-band. When the mature leaves were illuminated at -20 °C instead and immediately cooled [curve (b)], the glow curve is quite different a prominent A-band appears at -15/-20 °C, while the (Bj+B2)-band is much weaker and the Zy band is barely observable. Thus the A- and B-bands appear to be complementary to each other in amplitude illumination at -60 °C produces a strong B-band and no A-band, while illumination at -20° C produces predominantly A-band and much less B-band. Both the A...

Brassinolide concentrations ranging from 10 3 ppm to 10-1 ppm improved the greening of etiolated leaves, although the degree of greening was different for the two hybrids. 

Maize is a hot-weather crop. Table II shows that low temperature depressed the synthesis of chlorophyll in etiolated leaves exposed to light, and brassinolide relaxed the depression of chlorophyll synthesis, especially at low temperature. For example, the chlorophyll content of the control at 18 ° C was 68% less than that of control at 30 ° C. However, the chlorophyll content of brassinolide-treated leaves at 18 ° C was only 36-44.5% less than that of brassinolide-treated leaves at 30 ° C. A... 

Two forms of nitrite reductase have been isolated from scutella, roots and etiolated leaves of maize (Hucklesby et al., 1972 Dalling et al., 1973). The physical and biochemical characteristics of one form are nearly identical with those of the enzyme from the green leaf. Only one form of the enzyme was found in the green leaf. Except for differences in thermal stability, and ion charge, the properties of the second form are nearly identical with that of the enzyme from green leaves. The enzymes from the nonchlorophyllous tissue, like the enzyme from green leaves, can utilize reduced dyes or ferredoxin but not nicotanamide or flavin nucleotides as electron donors. 

Genomic DNA from maize (Zea mays L. cv. Golden Cross Bantam) was isolated from etiolated leaves as previously described (6). 

The wheat leaf has a developmental gradient alon its length with a zone of cell division at its base and oldest tissue at its tip. We have used this feature to study the developmental expression of the genes for these enzymes. The mRNA levels for each are highest below the middle of leaf and decrease towards the tip (1,6,7). None was found in the roots or in etiolated tissues. Even a very brief illumination resulted in the accumulation of a detectable amount in the etiolated leaves. In contrast, mRNA for the cytosolic PGK was found in about the same amount in all tissues examined. Accumulation of the FBP follows the same pattern as that of its mRNA but, in contrast, its levels do not decline again in older tissues suggesting that the protein is relatively stable. 

Etiolated leaves first irradiated with one ms white flash and then kept in darkness for 120 min at 26 C exhibited the 77 K fluorescence induction curve shown in Fig. 1. The fluorescence intensity increased from a Fo level to a Fp, level with a half-time of 100-120 ms. The relative amplitude of the variable fluorescence F was calculated using the formula Fy = (F - Fo )/Frt. 

PHOTOREDUCTION OF THE PROTOCHLOROPHYLLIDE INTO CHLOROPHYLLIDE IN ETIOLATED LEAVES AND COTYLEDONS FROM PMSeOLUS VULGARIS CV COMMODORE. 

On the contrary, an absorbance increase at 520 nm ( i 6520) occurs upon excitation by R or FR light in etiolated leaves... 

Red or far-red light-induced 520 nm absorbance changes in etiolated leaves (a), in 1 ms-flashed etiolated leaves (b) or in green leaves (c). 

The light-induced 520 nm absorbance increase is not correlated to protochlorophyllide photoreduction since 1) a 1 ms-flashed etiolated leaf shows a kinetic similar to that of an etiolated leaf, although the latter has not regenerated more than 15% of the amount of protochlorophyllide present in etiolated leaves (5) 2) the absorbance change is reversible both under R and FR light. 

The quantitative aspects of changes in various intracellular pools of NADPH protochlorophyllide oxidoreductase (POR) are important for understanding the principles of operation of the multienzyme system of chlorophyll biosynthesis which proteins are encoded by nuclear DBA and synthesized in the cytoplasm. The application of immunochemical methods /I,2/ allowed to detect loss of POR in the system of intraplastid membranes of etiolated leaves under illumination. In this work the enzyme-linked immunosorbent assay (ELISA) was employed for quantification of POR in different intracellular compartments of postetio-lated and green barley seedlings. 

GAROTENOID BIOSYNTHESIS IN GREENING ETIOLATED LEAVES A DEUTERIUM LABELLING EXPERIMENT... 

In etiolated leaves the majority of PChlide is connected to the PChlide reductase enzyme which, according to the ternary complex model, bounds NADPH molecule(s), too (4). This complex is an integral unit of prolamellar bodies (PLB) and in vivo can be characterized with a 650 nm absorption and 657 nm low-temperature fluorescence emission maximum (5). However, PChlide or PChl molecules must be connected to other components of the etioplast inner membranes, these molecules can regenerate the phototransphormed PChlide or cannot be phototransformed at all (2). These molecular complexes have absorption maxima at 628-630 and 635-637 nm (6). 

Photoreduction of the ProtochlorophyUide Into ChlorophyUide in Etiolated Leaves and... 

S, Etiolated leaves (/tg/mg protein) Zea mays, shoots (nuclei) 1.3 9.2 ... 

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