yielded two substances which gave a yellow color with 2,4-dinitrophenylhydrazine and had the same Rp-values as p-hydroxybenzaldehyde and v an illin7. The insoluble residue could therefore be described as lignin-like m aterial. In view of the above men tioned work on the enzymology of lignin biosynthe sis in the soybean cell cultures it was, however, necessary to obtain more precise inform ation on the structure of the lignin formed by the cell cul tures. Since 13C-NMR-spectroscopy has been shown to be a valuable method for the classification of lignins of different origin 9 we have now applied this method for the characterization of the lignin from soybean cell cultures. Evidence is presented that this lignin is similar to hardwood lignin. M aterials and M ethods Cell culturesSoybean cells (G lycine m ax) were propagated at 27 °C in a ferm enter containing modified B5 meRequests of reprints should be sent to Dozent Dr. H. Nimz, Polymer-Institut der Universität D -7500 K arlsru he 21 , Hertzstr. 16. dium as described previously 4. Cells used for lignin preparation were of different age.

During the last tcn years or so, variation in secondary plant products between different taxa has been incrcasingly uscd in systematic and evolutionary studies. However successful this approach has been, it now nceds to be tempered by a consideration of the underlying variation in the biosynthetic pathways leading to the compounds in question. In some cases cognate compounds are formcd by two or more pathways in different taxa; in others the same biosynthetic route is regulatcd in different ways. lt is necessary, therefore, to examine the ontogeny and characteristics of thc individual enzymes involved. Examples of such approaches are givcn for a !arge number of different classes of compound. including naphthoquinoncs, flavonoids, meta-carboxy aromatic amino acids.branched chain sugars and Iignin. INTRODUCTIONThe contribution which the investigation of biosynthetic pathways can make to the study of evolution and systematics can be divided into three main areas: (a) the elucidation of general biosynthetic patterns by tracer techniques; (b) comparative biochemistry of individual biosynthetic steps and ofthe enzymes involved; and (c) comparative biochemistry ofregulatory systems.A large number of biosynthetic pathways in higher plants have now been outlined, mainly by tracer techniques, and it is not my intention to cover the whole field in this review. Rather I should like to concentrate my presentation on a few selected pathways. Unfortunately, the situation is completely different in the case of areas (b) and (c). The enzymology of biosynthetic pathways in higher plants isjust in its infancy, and here we have to rely heavily on knowledge gained with enzymes from lower plants and microorganisms. The same applies to our knowledge of regulatory systems.

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An enzyme preparation from parsley (Petroselinum hortense Hoffm.) catalyses the formation of apiin (7-0[p-D-apiofuranosyl( 1+2)2)p-D-glycosyl] -5,7,4'-trihydroxyflavone) from 7-O-(p-D-glycosyl)-apigenin and UDP-apiose and of the corresponding chrysoeriol-7-apiosyl-glucoside from 7-O-@Dglucosyl)-chrysoeriol and UDP-apiose. Neither free apiose nor cyclic apiose-1,2-phosphate can function as a substrate for the transfer reaction.

The ethanolic extract of 8-week-old parsley plants was chromatographed on Dowex-I x 2 with a concave gradient using the buffer system of Hurlbert. After further purification on carboncelite columns, paper chromatography and high-voltage electrophoresis, 120 pmoles of a homogeneous UDP-sugar fraction were obtained. The sugars present in this fraction were identzed after acid or enzymatic hydrolysis (Crotalus adamanteus venom, acid phosphatase) by various chemical and enzymatic tests. A modified Dische test which is specific for apiose and a quantitative determination of D-xylose with D-glucose-oxidase were developed.According to the analytical investigations the UDP-sugar fraction 'had the iollowing composition (pmol) : UDP-D-glucose (84), UDP-D-galactose (27), UDP-D-xylose (4), UDP-L-arabinose (2), UDP-fructose (0.42), UDP-L-rhamnose (2.4), and UDP-apiose (0.18). The presence of UDPapiose in parsley strongly corroborates the proposed biosynthetic pathway for the formation of D-apiose via UDP-D-glucuronk acid.