Fukuju Yamamoto

Growth, Morphology, Stem Anatomy, and Ethylene Production in Flooded Alnus Japonica Seedlings

Flooding of soil of potted, 24-month-old Alnus japonica seedlings for 24 days altered growth, morphology, stem anatomy, and ethylene production. This species exhibited high adaptability to soil flooding by forming adventitious roots that grew through hypertrophied lenticels. Aerenchyma tissues were observed in the bark of the adventitious roots. Flooding slightly reduced height growth and greatly stimulated diameter growth of submerged portions of stems in comparison with unflooded seedlings. Diameter growth in flooded seedlings was largely due to increases in both the number and size of wood fibres produeed during the flooding period. Flooding did not affect biomass increment of leaves and stems but reduced the total dry weight increment of the root system even though abundant adventitious roots had formed. Ethylene production in the submerged portions of stems was greatly increased by flooding. Morphological and anatomical responses of Alnus japonica seedlings to flooding are discussed.

Effects of Depth of Flooding on Growth and Anatomy of Stems and Knee Roots of Taxodium Distichum

Depth of flooding of Taxodium distichum trees influeneedin height and diametergrowth, formation of knee roots , and anatomy of sterns and knee roots. Height growth was progressively redueed and diameter growth was inereased as the level of the flood water was inereased. Formation of knee roots deereased as the depth of flooding inereased. Traeheids in the submerged portions of sterns of deeply flooded trees were shorter, slightly wider, and had thinner walls than traeheids of shallowly flooded trees. The inner bark of the submerged sterns of deeply flooded trees had wider phloemrays and more intercellular space than the bark of shallowly flooded trees. The xylem anatomy of knee roots resembled that of the xylem in the submerged portions of sterns of deeply flooded trees. Flooding stimulated ethylene produetion by stern bark and apieal portions of knee roots. An interaetive role of ethylene and auxin in anatomical responses of Taxodium to the flooding is postulated.

Regulation by uniconazole-P and gibberellins of morphological and anatomical responses of Fraxinus mandshurica seedlings to gravity.

The present study deals with roles of gibberellins (GAs) in gravitropic responses of woody stems of horizontally-positioned, 2-year-old seedling of Fraxinus mandshurica Rupr. var. japonica Maxim. The application of uniconazole-P, an inhibitor of GAs biosynthesis, to stem nodes at various concentrations significantly inhibited not only righting the stems but also wood formation. The application of GAs (GA3 and GA4) in combination with uniconazole-P negated the inhibitory effect of the treatment of uniconazole-P alone. The GAs alone did not affect wood formation, however, both GAs increased wood formation on both the upper and lower sides of horizontal stems with an increase in the concentration of combined uniconazole-P. In all of the seedlings, tension wood was formed on the upper side of stems. The application of uniconazole-P alone at various concentrations did not inhibit the formation of tension wood fibres.

A STUDY ON THE ROLE OF CALCIUM IN XYLEM DEVELOPMENT AND COMPRESSION WOOD FORMATION IN TAXODIUM DISTICHUM SEEDLINGS

One-year-old Taxodium distichum seedlings were decapitated and attached to plastic tubing for ‘force feeding’ of liquid media containing different levels of calcium regulating chemicals. The decapitated stems were either vertically placed or tilted at an angle of 45° to be gravitationally stressed. After an eight-week period of culture, diameter growth occurred at 1–3 cm below the cut ends and a large quantity of compression wood cells had differentiated on the lower side of tilted stems that were fed with a modified WPM control medium. However, the application of EGTA, a calcium chelating agent, and LaCl3, a calcium channel blocker, at concentrations of 20 or 50 mM and 1.0 mM, respectively, inhibited the formation of compression wood and the wall thickness of tracheid cells. The results suggested an involvement of calcium in the gravi-stimulated compression wood formation of conifers.

RAPD Variation among Quercus Species Distributed in Temperate Deciduous Forests of the Hiruzen Mountains

Species of the genus Quercus are widespread in the northern hemisphere. In eastern Asia, Quercus serrata Thunb., Q. mongolica Fisch. ex Ledeb. var. crispula (Blume), Q. dentata Thunb. and Q. aliena Blume, which are classified into the section Prinus, are distributed in temperate deciduous forests of north-eastern China, the Korean Peninsula, and the Japanese Islands. Several presumptive hybrids of these Quercus species have been recorded in the same locations. These species of the section Prinus and the presumptive hybrids are very important for economic utilization and investigations of ecology, forest genetics, and species evolution. In the vicinity of the Hiruzen mountains, rising over Tottori and Okayama Prefectures, Japan, Q. serrata, Q. mongolica var. crispula, and Q. dentata are distributed together in temperate deciduous forests at altitudes from 550 m to 650 m. Quercus takatorensis Makino and Q. anguste-lepidota Nakai, which are presumed to be the intermediate types of the three Quercus species, are commonly observed in the same forests. Hashizume et al. (1994) reported that the morphological measurements and structures of leaves, cupules, and acorns of the presumptive intermediate types indicated intermediate characteristics of the three Quercus species. In fact, the flowering season of the three Quercus species overlaps each year in May, suggesting the possibility of cross pollination among them in the Hiruzen Forest of Tottori University Forests (Lee, unpublished data). However, there is no direct evidence to prove natural interspecific hybridization occurring among the species of the section Prinus. In general, genetic markers have many potential applications in forest genetics and tree breeding research, including genetic diversity, population structure, phylogeny, mating systems, and tree classification. The lack of suitable markers has hindered the direct analysis of genetic structures in plant species. Isozymes have been useful to estimate genetic diversity of plant populations (Hokanson et al., 1993; Hyun et al., 1987). The isozyme analysis has an advantage in its simplicity and rapidity, however, orffy a limited number of polymorphic loci are available for use as genetic markers. Recently, a method for comparing random amplified poly1Present address: 5-72-4, Tachikawa-cho, Tottori 680,

Effects of Irregular Saltwater Submergence on Taxodium distichum Seedlings

Abstract The growth response and photosynthetic activity of Taxodium distichum in relation to the leaf and root Na+ content was assessed with the use of 2-year-old seedlings submerged in saline. Seedlings were submerged in water containing 0, 4000, and 8000 ppm NaCl during May, July, and September, respectively. Submergence and soil flooding with fresh water (control) did not inhibit vertical or lateral seedling growth. No morphological changes were observed during submergence in salt water; however, in July and September, leaf injury and shoot dieback were observed in the drained seedlings. Saline submergence in July and September inhibited photosynthesis and decreased the leaf and stem biomass but did not affect the root biomass. The seedling Na+ and K+ ion contents increased with increases in salt concentration; however, in May, the ion contents did not increase significantly. Such seasonal differences in ion content might lead to variations in the extent of leaf damage and growth inhibition after saline submergence in T. distichum seedlings.

Osmolyte accumulation in leaves of Tamarix ramosissima growing under various soil conditions in the Colorado River basin

Tamarixramosissima is a dominant species in desert riparian ecosystems in the western USA. It is a phreatophytic halophyte, with salt glands on the leaves. While osmoregulation is essential for turgor maintenance under high salinity, the dose–response relationship to salinity of various osmolytes in plants with salt glands is still unknown. We profiled crude leaf extracts of T. ramosissima to identify the metabolic compounds that contribute to its salt tolerance. We compared leaf cation, soluble sugar, amino acid, and betaine content among T. ramosissima samples from five points along the Colorado River. The leaf sodium content of T. ramosissima trees increased with increasing soil salinity. Under high salinity conditions, soluble sugar and betaine content did not increase, but amino acids did. The increase in proline accumulation was highly and positively correlated with leaf sodium content. Thus, proline appears to be the essential osmolyte that T. ramosissima accumulates in response to severe salt stress in desert riparian areas of the USA.

Flooding adaptations of wetland trees

A reduction in gas exchange between the air and the rhizosphere causes a major problem for terrestrial plants (Jackson & Drew 1984; Visser & Vosenek 2004). Soil flooding or submergence sets in motion a series of physical, chemical, and biological processes that profoundly influence the quality of soil as a medium for plant growth (Ponnam peruma 1984). In well-drained soils, the stability of the gas composition is maintained by rapid gas exchange between the soil and air, despite oxygen consumption, carbon dioxide production, and nitrogen fixation by soil organisms. In contrast, soil flooding or submergence causes oxygen depletion and carbon dioxide accumulation in the rhizosphere and plants (Jackson & Drew 1984; Ponnamperuma 1984; Greenway et al. 2006). These events lead to an energy deficit in plants through the inhibition of aerobic respiration and disturbance of photosynthetic processes. The accumulation of phytotoxic compounds, including reduced forms of iron and manganese, ethanol, lactic acid, acetaldehyde, aliphatic acids, and cyanogenic compounds, is also a major problem for plants (Ponnamperuma 1984). The effects of such compounds on root metabolism cause the inhibition of root growth and development (Jackson & Drew 1984; Ponnamperuma 1984; Armstrong et al. 1996; Armstrong & Armstrong 1999; Pezeshki 2001; Greenway et al. 2006). Thus, vegetation in the peripheral zone of lakes and swamps typically consists of flood-tolerant species that have specific mechanisms to tolerate excessive water.

Effects of injection of Ethrel, methyl jasmonate, and salicylates and Raffaelea Quercivora inoculation on sapwood discoloration in Quercus Serrata

Ethrel (Et), methyl jasmonate (MJ), methyl salicylate (MS), sodium salicylate NS), and mixed combinations of these chemicals were horizontally injected into stems to induce defense responses in Quercus serrata Thunb. Four months after wounding with the application of those chemicals, the extent of sapwood discoloration was observed in tangential and axial directions. The combination of MJ and Et (MJ+Et) induced the greatest discoloration among all treatments. Sodium salicylate (NS) or methyl salicylate (MS) alone increased the discolored area to a lesser degree than did MJ, but defensive responses were obviously more accelerated when the former were added to the latter in the combination treatments. In particular, induced discoloration was noticeably achieved following MJ or Et combined with NS rather than as individual treatments. In contrast, neither salicylate appeared to promote discoloration when combined with the MJ+Et treatment. Wounds challenged with an inoculation by a bark beetle vectored fungus, Raffaelea quercivora, developed significantly greater sapwood discoloration than did nonpathogen inoculation, in all directions.

Anatomy of Stem Hyperplasia Called Tokkuri Disease in Chamaecyparis Obtusa

The stem hyperplasia called tokkuri-disease in Japan was observed on the lower part of stems of 25-29-year-old Chamaecyparis obtusa trees. The anatomy of the hyperplastic portions was characterised by rapid proliferation of the cambium, short and thin-walled tracheids, a large number of multiseriate rays, and thickened bark. The cambial activity in the hyperplastic portion was high in July and remained high until mid-October. Transverse sections show the hyperplastic portions of the cambium and growth ring boundaries are sinuous, whereas those in non-hyperplastic portions of the same trees or in normal trees are not. The sinuosity of cambia was closely related with cambial activity. The ecological and physiological causes of stem hyperplasia are discussed on the basis of anatomical studies.