Cambial tissues

Preteatment with pectinases improves meehanieal debarking of wood significantly. In addition to polygalacturonase, enzymes hydrolysing the neutral polymers in cambial tissue (arabinanase, galactanase, and glucanase) are needed for effective solubilization of spruce cambium. 

Cytokinins were found by bioassay of extracts of cambial scrapings (Bottom-ley et al. 1963) and of the inner bark of Populus trees (Nitsch and Nitsch 1965). The latter authors had guessed that Populus cambial zone would contain cytokinins because it was well known as a source of Gautheret s (1959) cambial tissue cultures, which did not require added cytokinin for growth. Data of Letham (1967) support the view that carrot cambium contains more cytokinin than does phloem or xylem, as Jacobs (p 127, 1979) pointed out. Rogozinska (1967), studying Scots pine, also reported cytokinin activity from extracts of bark + cambium . 

Shepherd KR, Rowan KS (1967) Indoleacetic acid in cambial tissue of radiata pine. Aust J Biol Sci 20 637-646... 

An extensive investigation of the polysaccharides found in cambial tissue of Populus tremuloides and Tilia americana has been carried out. The tissue from poplar contained pectic material (40%), arabinogalactan (12%), xylan (10%), xyloglucan (6%), glucomannan (1%), cellulose (21%), and protein (10%). The tissue from basswood had a very similar composition except that it contained more xyloglucan and less xylan. Except for the xylan and glucomannan content, the cambial tissue from these two woods had compositions very similar... 

Simson B W, Timell T E 1978 Polysaccharides in cambial tissues of Populus tremuloides and Tilia americana. I. Isolation, fractionation, and chemical composition of the cambial tissues. Cellul Chem Technol 12 39-50... 

Arabinoglycoproteins occur in seeds in cell and tissue cultures (19), and in cambial tissue. An example of the extraneous materials containing bound amino acids and deposited on a plastic dish by Douglas-fir (Pseudotsuga menziesii) cells growing into sphaeroblasts is shown in Fig. 5.1.1 (cf., 13 p 36-71). 

Particularly in the wetter types, where grass growth is greater and fires therefore hotter, many of the trees are low in stature (<15 m) and have many contorted branches. Many have thick bark that probably helps to protect the delicate cambial tissues from the heat of fires (for profile diagrams of such woodlands see Langdale-Brown et al., 1964, Figures 13-16). Similar features are found in many cerrado trees (Oliveira-Filho and Ratter, 2002). 

Further work on the mode of formation of the phenylpropanoid precursors of lignin in higher plants has also been published. Confirmatory observations on the stereochemical mode of action of tyrosine ammonia lyase have been made and a review of the biochemical properties of phenylalanine ammonia lyase has been compiled by Towers and Camm . Zenk and his group . using a cell free system from cambial tissue of Salix alba and a cell free preparation from phytotron grown Forsythia species, have demonstrated for the first time the reduction of ferulate (7) to coniferyl alcohol (8) in a higher plant. The conversion is dependent on ATP, co-enzyme A and reduced pyridine nucleotides and Zenk has formulated the reaction sequence as shown below (7 - 8). 

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