Differences between Gymnosperms

Leavitt, S.W. and Newberry T. 1992 Systematics of stable-carbon isotopic differences between gymnosperm and angiosperm trees. Plant Physiology (Life Science Advances) 11 Til-161. 

The PAL activity that is necessary for lignin formation occurs in the cytoplasm or bound to the cytoplasmic surface of the endoplasmic reticulum membranes. The cinnamic acid produced is probably carried on the lipid surface of the membranes, since it is lipophilic, and it is sequentially hydroxylated by the membrane-bound hydroxylases (47,50). In this way there is the possibility of at least a two-step channeling route from phenylalanine to p-coumaric acid. The transmethylases then direct the methyl groups to the meta positions. There is a difference between the transmethylases from angiosperms and those from gymnosperms, since with the latter... 

Fig. 4.3 Chemical composition of major coal macerals and plant tissues plotted on a van Krevelen diagram (after Tissot Welte 1984 Hedges et al. 1985). Lignin incorporates differences between angiosperms (ang) and gymnosperms (gym) (after Hatcher 1990).

In woody gymnosperms, there are significant differences in the distribution, reactivity and physical properties of protolignins found in the compound middle lamella and the secondary wall (1-3). Additionally, variations between lignins in vessels and fibers have also been noted (3). All of these... 

Fig. 5.3 Plots of some monosaccharides (expressed as wt % of total amount of combined lyxose, arabinose, ribose, xylose, rhamnose, fucose, mannose and galactose), showing (a) differentiation of angiospermous and gymnospermous vascular plant sources from total marine plankton, and (b) distinction between different types of higher plant sources (after Cowie Hedges 1984).

Biosynthesis of Lignin.—The mechanism of biosynthetic differentiation between the different lignins produced in gymnosperms and angiosperms has been explored by Shimada et al.f employing both enzymic and tracer procedures. The pathway of synthesis of the —C3 lignin precursors appears to... 

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