The effects of air pollutants on the epicuticular wax structure of conifer needles and the ecophysiological consequences of the injuries are reviewed on the basis of published literature and the authors' recent investigations. Degradation of the epicuticular waxes, which appears as a fusion of wax tubes in the epistomatal chambers and finally results in an amorphous appearance of the waxes, is the most common micromorphological injury type observed in studies on the genera Abies, Larix, Picea, and Pinus. The rate of erosion correlates well with the level of air pollution, but clear evidence for the specificity of the symptoms for different air pollutants has not been observed. It is concluded that the erosion of the epicuticular waxes, a phenomenon with a large geographic distribution, is a relevant factor of the multiple forest decline syndrome. Erosion of the waxes can change needle wettability and rain retention. Increased needle wettability and permeability of the cuticles can result in enhanced leaching of nutrients and uptake of pollutants. Increased or decreased stomatal and cuticular diffusion resistance of the needles leads to altered transpiration rates. Due to the changed chemical microenvironment of the needles, the conifers are predisposed to various biotic and abiotic stresses. Because the epicuticular waxes are one of the first targets of a variety of air pollutants, they can widely be used as an early indicator of air pollution effects.

Triterpenoid compounds extracted from fruits and leaves of lingonberry (Vaccinium vitis-idaea L.) collected in Finland and Poland were identified and quantitated by GC−MS/FID. The main lingonberry triterpenoid profile consisted of αamyrin, β-amyrin, betulin, campesterol, cycloartanol, erythrodiol, fern-7-en-3β-ol, friedelin, lupeol, sitosterol, stigmasterol, stigmasta-3,5-dien-7-one, swert-9(11)-en-3β-ol, taraxasterol, urs-12-en-29-al, uvaol, oleanolic acid, and ursolic acid. To our knowledge, this is the first thorough description of triterpenoid compounds in this species. Ursolic acid was identified as a principal triterpene in lingonberry fruit. The influence of geographical origin on the level of individual triterpenoid compounds was examined, and considerable variations in triterpenoid profile between berries and leaves obtained from the two locations were observed. The most striking difference concerned the occurrence of fernenol and taraxasterol, which were found to be the major triterpenol in lingonberry leaves of Finnish and Polish origin, respectively.

Triterpenoid compounds found in free and ester forms in extracts of entire fruits and leaves and in fruit and leaf cuticular waxes of bilberry (Vaccinium myrtillus L.) collected in Finland and Poland were identified and quantitated by gas chromatography-mass spectrometry coupled to a flame ionization detector (GC-MS/FID). The main bilberry triterpenoid profile consisted of α- and β-amyrin, α- and β-amyrenone, campesterol, cholesterol, citrostadienol (in berries), cycloartanol, erythrodiol, lupeol, 24-methylenecycloartanol, sitosterol, sitostanol, stigmasterol, stigmasta-3,5-dien-7-one, uvaol, oleanolic and ursolic aldehydes, and oleanolic, ursolic, 2α-hydroxyoleanolic, and 2α-hydroxyursolic acids. Friedelin and D:A-friedooleanan-3β-ol were found only in Finnish plants, whereas D:C-friedours-7-en-3β-ol and taraxasterol were found only in Polish plants. To our knowledge, this is the first thorough description of triterpenoid compounds in this species. The presented results revealed that the triterpenoid profile of bilberry varied considerably between different organs of the plant, regardless of the plant origin, as well as between plant samples obtained from the two geographical locations.

The effects of enhanced UV‐B radiation on the needle anatomy of loblolly pine (Pinus taeda L.) and Scots pine (Pinus sylvestris L.) were studied in the field under supplemental UV‐B radiation supplied by a modulated irradiation system. The supplemental UV‐B levels were designed to simulate either a 16 or 25% loss of stratospheric ozone over College Park, Maryland. Enhanced UV‐B radiation caused different responses in these two species. The needles of loblolly pine had larger amounts of tannin in the lumen of epidermal cells and more wall‐bound phenolics in the outer epidermal walls of UV‐B‐treated needles, whereas the most pronounced effect on Scots pine needles was increased cutinization. In both species, the outer epidermal cell walls thickened and the needle cross‐sectional and mesophyll areas decreased (statistically significantly only in Scots pine). This suggests that more carbon may have been allocated to the protection mechanisms at the expense of photosynthetic area. The difference in response between these species suggests that the response to UV‐B radiation is not mediated by a single mechanism and that no generalization with regard to the effects of UV‐B on conifers can be made.

No abstract

No abstract

No abstract

We examined the effects of three foliar potassium concentrations (high, intermediate and low) on the morphology, ultrastructure and polyamine concentrations of current-year and 1- and 2-year-old needles of 30-year-old Scots pine (Pinus sylvestris L.) trees. Foliar K concentration had only a slight effect on needle morphology. The sclerenchyma cell walls were thinner, the xylem area was larger, and the resin ducts were smaller in needles with a low K concentration than in needles with a high or intermediate K concentration. In addition, the bundle sheath cells were collapsed in needles having a low K concentration. The secondary growth of phloem tissue and the mesophyll area were greater in needles with a high or intermediate K concentration than in needles with a low K concentration, possibly indicating greater production of photoassimilates in these trees. At the ultrastructural level, mesophyll cells with enlarged central vacuoles and small vacuoles containing electron-dense material were common in needles having a low K concentration. Enlargement of the central vacuole coincided with an exponential increase in putrescine concentration in needles with a low K concentration, suggesting that the central vacuole may function as a storage site for putrescine.