Vascular plants applications

Goni, M.A., and Hedges, J.I. (1990a) Potential applications of cutin-derived CuO reaction products for discriminating vascular plant sources in natural environments. Geochim. Cosmochim. Acta 54, 3073-3083. 

Other studies, such as Py-GC/MS characterization of peat components also have been reported. In a study done using Py-GC/MS, subfossil Sphagnum leaves and rootlets of heathers (Ericaceae) were analyzed, the Ericaceae having been determined to be the source of aliphatic hydrocarbons in peat [33]. Also, the sources of other peat components were analyzed by pyrolytic techniques. As an example, the fine-grain peat fraction was found to contain monosaccharides mainly from microbial carbohydrates, while coarse-grained peat samples were found to contain monosaccharides from vascular plant carbohydrates [34]. Peat classification has also been done based on its pyrolysis products [35]. A few other applications of peat pyrolysis will be discussed in Part 3 of this book. 

The induction of PAL activity at the onset of vascular differentiation can be shown by the use of plant tissue cultures (37-39). Xylem cells with secondary and lignified walls are differentiated over a time course of 3-14 days by the application of the plant growth factors naphthylene acetic acid (NAA) and kinetin in the ratio 5 1 (1.0 mg/liter NAA, 0.2 mg/liter kinetin) to tissue cultures of bean cells (Phaseolus vulgaris) (37,40). The time for differentiation varies with the type of culture, solid or suspension, and with the frequency and duration of subculture, but for any one culture it is relatively constant (37,41,42). At the time of differentiation when the xylem vessels form, the activity of PAL rises to a maximum. The rising phase of the enzyme activity was inhibited by actinomycin D and by D-2,4-(4-methyl-2,6-dinitroanilino)-N-methylpropionamide (MDMP) applied under carefully controlled conditions (42). This indicated that both transcription and translation were necessary for the response to the hormones. Experiments using an antibody for PAL and a cDNA probe for the PAL-mRNA have also shown that there is an increase in the amount of transcript for PAL during the formation of lignin when Zinnia mesophyll cells are induced to form xylem elements in culture (Lin and Northcote, unpublished work). 

Labeling of plants via a nutrient solution is more efficient than by soil application due to the possible adherence of the added mineral on soil components. Stem injection may be an efficient labeling technique, but until the mineral complexes which are transported in the vascular system are clearly defined, this technique may not result in deposition of isotopes which are characteristic of field grown crops. 

Insecticides with systemic action are taken up relatively quickly by the plants and transported into the vascular system. According to the type of application, uptake occurs through the roots or the parts of the plant above ground. Distribution is chiefly by the xylem, but is also possible by the phloem and by diffusion from cell to cell. The persistence of activity is dependent on the type of substance, the intensity of breakdown in the plant or the soil, and environmental conditions. A much longer period of protection can be maintained if, by application of granulates at drilling or planting out, a depot of the substance is created in the soil from which the active substance is released slowly and taken up by the plants. 

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