Effects of fire-derived charcoal on soil properties and seedling regeneration in a recently burned <Emphasis Type="Italic">Larix gmelinii</Emphasis>/<Emphasis Type="Italic">Pinus sylvestris</Emphasis> forest

Purpose  

Fire is a primary form of disturbance in boreal ecosystems. Charcoal is an important by-product of forest fire and has been reported to have the potential to influence the plant community establishing after fire. To date, however, no study has effectively tested the relationship between charcoal and plant regeneration in the actual post-fire forests. To determine the contribution of charcoal to soil properties and plant regeneration after forest fires, we conducted in situ investigations concerning the relationship between charcoal and the plant–soil system.     

Strawberry cultivar identification based on hypervariable SSR markers

We genotyped strawberry cultivars by two newly selected and two previously reported SSR markers. All four markers produced interpretable electropherograms from 75 accessions consisting of 72 Fragaria × ananassa cultivars or lines and three octoploid Fragaria species accessions. These SSR markers were highly polymorphic; in particular, one of the newly developed markers, FxaHGA02P13, was capable of distinguishing all of the accessions except for a mutant strain that was derived from another accession in the set. When two markers were combined, all 48 full-sib individuals could be distinguished. Fingerprinting patterns were reproducible between multiple samples, including the leaves, sepals, and fruit flesh of the same accession. Principal-coordinate analysis of the 75 accessions detected several groups, which reflect taxon and breeding site. Together with other available markers, these SSR markers will contribute to the management of strawberry genetic resources and the protection of breeders’ rights.     

Climatic responses of tree-ring widths of <Emphasis Type="Italic">Larix gmelinii</Emphasis> on contrasting north-facing and south-facing slopes in central Siberia

An analysis was performed on the climatic responses of the radial growth of Larix gmelinii (Rupr.) Rupr. on contrasting north-facing and south-facing slopes in Tura, central Siberia. We developed chronologies of tree-ring width for four plots, designated as north-upper, northlower, south-upper, and south-lower. Both residual and standard chronologies of tree-ring widths exhibited a significant positive correlation with temperature from the end of May until early June in all four plots. The chronologies of ring width did not reveal any major difference in the response to temperature among the four plots. The standard chronologies of ring widths on the north-facing slope were negatively correlated with precipitation during the winter (October–April) and in early and mid-May, whereas the residual chronologies did not reveal clear relationships with precipitation during the winter and May. The significant correlation between ring width and temperature from the end of May until early June indicates that temperatures in springtime play a significant role in the radial growth of L. gmelinii. The negative correlations between standard chronologies of tree-ring width and precipitation in the winter and in May on the north-facing slope indicate that lowfrequency fluctuations in snowfall have negative effects on the radial growth. However, these effects vary and depend on the microscale topography. Part of this report was presented at the 55th Annual Meeting of the Japan Wood Society, March 2005, Kyoto     

Characterization of new thioacidolysis products of sinapyl aldehyde and coniferyl aldehyde

To elucidate the chemical structure ofp-hydroxycinnamyl aldehyde moieties of abnormal angiosperm lignins of cinnamyl alcohol dehydrogenase down-regulated plants, sinapyl and coniferyl aldehydes were subjected to thioacidolysis. and the products were analyzed by gas chromatograph-mass spectrometer (GC-MS). The chromatograms indicated that two pairs of new isomeric compounds were released during thioacidolysis of sinapyl and coniferyl aldehydes, respectively, together with the previously found products. These products were also found in the thioacidolysis products of dehydrogenation polymer incorporatingp-hydroxycinnamyl aldehydes. The new compounds had the novel indane structure in that they position of the side chain was linked to an aromatic ring. In the case of sinapyl aldehyde, these isomer compounds were the main products, which indicated different reactivities of sinapyl and coniferyl aldehydes during thioacidolysis.Part of this paper was presented at the TAPPI Pulping Conference. Nashville, October 1996; and the 41st Lignin Symposium, Nagoya. October 1996     

Look back over the studies of lignin biochemistry

The role of the cinnamate pathway in monolignol biosynthesis based on feeding experiments with lignifying plant stems and characterization of the enzymes in the pathway, O-methyltransferase (OMT), cinnamyl alcohol dehydrogenase (CAD), etc. is discussed. Monolignol biosynthesis via metabolic grids according to newly characterized enzymes in the pathway is also reviewed and discussed. The cleavage mechanisms of side chains and aromatic rings by lignin peroxidase and laccase elucidated by using ¹⁸O, ²H, and ¹³C labeled lignin substructure dimers and DHP with ¹⁸O₂ and H₂ ¹⁸O are reviewed. Finally, the prospects of lignin biochemistry in the wood and paper industries are discussed according to the recent progress on gene technology on wood formation and microbial degradation of lignin.     

Effects of elevated CO2 concentration on growth, annual ring structure and photosynthesis in Larix kaempferi seedlings

We evaluated the effects of elevated carbon dioxide concentration ([CO2]) and two nutrient regimes on stem growth rate, annual ring structure and temporal variations in photosynthetic characteristics of seedlings of Japanese larch (Larix kaempferi (Lamb.) Carr.). Seedlings were grown in phytotron chambers in an ambient (360 ppm) or an elevated (720 ppm) [CO2] in two nutrient regimes for one growing season. Elevated [CO2] reduced stem height and increased stem basal diameter compared with ambient [CO2]. The effect of elevated [CO2] on growth tended to be greater at high-nutrient supply than at low-nutrient supply. Elevated [CO2] had no significant effect on ring width or the number of tracheids per radial file. There was no obvious difference in cell wall thickness or the relative area of the cell wall between seedlings grown in ambient or elevated [CO2]. Although growth in elevated [CO2] resulted in a slight increase in cell diameter, the increase had a relatively minor effect on the relative area of the cell wall. Net assimilation rate increased in response to elevated [CO2]; however, the increase in whole-crown photosynthetic rate (Total Agrowth) in seedlings in the elevated [CO2] treatment was minimal because of the smaller specific needle area and acclimation of the photosynthetic characteristics of the needles to the growth [CO2]. In conclusion, we observed no obvious enhancement in the capacity for carbon fixation in Japanese larch seedlings grown in the presence of elevated [CO2] that might be attributable to changes in stem growth. However, elevated [CO2] caused changes in the temporal pattern of stem growth and in some anatomical features of the tracheids.     

Interspecific variation of photosynthesis and leaf characteristics in canopy trees of five species of Dipterocarpaceae in a tropical rain forest

Photosynthetic rate, nitrogen concentration and morphological properties of canopy leaves were studied in 18 trees, comprising five dipterocarp species, in a tropical rain forest in Sarawak, Malaysia. Photosynthetic rate at light saturation (Pmax) differed significantly across species, varying from 7 to 18 micro mol m(-2) s(-1). Leaf nitrogen concentration and morphological properties, such as leaf blade and palisade layer thickness, leaf mass per area (LMA) and surface area of mesophyll cells per unit leaf area (Ames/A), also varied significantly across species. Among the relationships with leaf characteristics, Pmax had the strongest correlation with leaf mesophyll parameters, such as palisade cell layer thickness (r2 = 0.76, P < 0.001) and Ames/A (r2 = 0.73, P < 0.001). Leaf nitrogen concentration and Pmax per unit area also had a significant but weaker correlation (r2 = 0.46, P < 0.01), whereas Pmax had no correlation, or only weakly significant correlations, with leaf blade thickness and LMA. Shorea beccariana Burck, which had the highest P(max) of the species studied, also had the thickest palisade layer, with up to five or more layers. We conclude that interspecific variation in photosynthetic capacity in tropical rain forest canopies is influenced more by leaf mesophyll structure than by leaf thickness, LMA or leaf nitrogen concentration.     

Insect antifeedant activity of flavones and chromones against Spodoptera litura

The antifeedant polymethylated flavones 5-hydroxy-3,6,7,8,4'-heptamethoxyflavone, 5-hydroxy-3,6,7,8-tetramethoxyflavone, and 5,6-dihydroxy-3,7-dimethoxyflavone have been isolated from the cudweed, Gnaphalium affine D. Don (Compositae). These flavonoids and authentic analogues showed insect antifeedant activity against the common cutworm (Spodoptera litura F.). In a previous paper, it was suggested that there was no substituent on the B-ring of the flavonoid for the beneficial antifeedant activity against the common cutworm. These flavonoids having a phenyl group as the B-ring and the chromone as elimination of the B-ring from the flavonoids were used to test the hypothesis of the previously described B-ring effect. The known fact is that Sculletaria baicarensis (Rutaceae) produced the 2-phenyl flavone. Test compounds and their methylated derivatives were prepared from this material for the structure-activity relationship (SAR) study of insect antifeedant activity. In spite of the 2-phenyl flavonoids, some tested compounds did not show any insect antifeedant activity against the common cutworm, although these inactive flavonoids were deficient in the 6-substituent group on the A-ring of the flavonoid. This 6-position-substituted derivative almost showed strong insect antifeedant activity against common cutworm. Moreover, the tested flavonoids having a hydroxyl group as a substituent on any of the positions tended to increase the activity. These results suggested the importance of the 6-position substitution on the flavonoid; however, hydrophilic substituents decreased the activity. Baicalein (5,6,7-trihydroxyflavone) derivatives did not show any activity despite having the 6-substituent derivative. Although the activity of some chromones increased the activity of the flavone, the bulky B-ring was a disadvantage for the antifeedant activity. It was suggested that the charge on C(3) and C(5) of the flavonoid was important for the biological activity. Additionally, an adequate hydrogen bonding property, which is different from lipophilicity, was an advantage for the activity on the basis of a QSAR analysis.     

POSITIVE-CONTRAST ARTHROGRAPHY

Normal colony Beagle dogs were used to evaluate the effect of concentration, volume, and limb positioning on positive-contrast arthrography in the humeral joint. An 8.4% w/v (33.3 mg/ml ± volume) concentration of analytic grade metrizamide (33 mg/ml of iodine) was thought to provide arthrograms of the highest diagnostic quality. Optimal volume of contrast medium was 2–4 ml in dogs with weight of 7.0–15.6 kg (mean, 10.3 kg). Radiographs thought to be of greatest diagnostic value were those made with the dog in lateral recumbency and the limb positioned for neutral, traction, flexion, supination, and pronation views, plus a caudocranial radiograph made with the dog in dorsal recumbency and the limb in traction.