Climatic controls on distribution of Fagus crenata forests in Japan

Abstract. We used classification tree analysis to develop a climate‐based distribution model for Fagus crenata forests in Japan. Four climatic variables judged likely to affect the distribution of the species (summer and winter precipitation, minimum temperature of the coldest month and Kira's warmth index) were chosen as independent variables for the model. Latitudinal and longitudinal information was also used to examine effects of spatial autocorrelation on the model. The climatic factors associated with the distribution of the forests were analysed using a classification tree to devise prediction rules. Predicted areas of high probability for forest occurrence lay mainly on the Sea of Japan side of northern Honshu and southern Hokkaido. This is consistent with actual forest distribution. Some areas with high predicted probabilities of F. crenata forest occurrence were beyond the current natural northern range limits of these forests. Since these areas were widely scattered, it was assumed that the species has been hindered from colonizing them due to dispersal limitations. Deviance‐weighted scores, used to compare magnitudes of the contributions of predictor variables, revealed winter precipitation as the most influential factor, followed by the warmth index, the minimum temperature of the coldest month and summer precipitation. Attempts were made to generate ecological explanations for the effects of the four climatic factors on the distribution of F. crenata forests.     

Glyphosate and bioherbicide interaction for controlling kudzu (Pueraria lobata), redvine (Brunnichia ovata), and trumpetcreeper (Campsis radicans)

In controlled environment experiments, the bioherbicidal fungus Myrothecium verrucaria (Alb. & Schwein.) Ditmar:Fr. was tested alone, in combination with, prior to, and following treatment with glyphosate [N-(phosphonomethyl)glycine] for control of kudzu [Pueraria lobata (Willd.) Ohwi], redvine [Brunnichia ovata (Walt.) Shinners], and trumpetcreeper [Campsis radicans (L.) Seem. ex Bureau] at temperatures of 20, 30, and 40°C. At all temperatures, kudzu was most adversely affected by the fungus, followed by trumpetcreeper and redvine, as indicated by greater mortality and dry weight reductions. Trumpetcreeper and redvine mortalities and dry weight reductions significantly increased when the fungus was applied 2 days after the glyphosate treatment. Application of the fungus combined with or prior to glyphosate treatment resulted in reduced weed control. Although pathogenesis and mortality also occurred at 20°C, disease development was favored by higher temperatures (30 and 40°C). Infected weeds of each species exhibited similar disease symptomatology within 12 h following treatment at incubation temperatures of 30 and 40°C. Disease symptomatology was characterized by necrotic flecking on leaves that coalesced into large lesions. Symptoms progressed, initially infecting cotyledons and leaves, and later (within 48 h) producing stem lesions. The fungus sporulated profusely on infected tissue and was easily reisolated. These results suggest that timing of glyphosate application in relation to combined treatment with the bioherbicide M. verrucaria can improve the control of kudzu, redvine, and trumpetcreeper.     

野葛内生真菌的分离、鉴定及体外细胞毒活性

目的:药用植物内生真菌是一类重要的微生物资源,其代谢产物有着广泛的生物学活性。该研究拟从野葛(Pueraria lobata(Willd.)Ohwi)中分离有细胞毒活性的内生真菌。方法:组织块改良法分离内生真菌;细胞毒活性测定采用Alamar blue法;结合形态学和分子生物学方法进行菌种鉴定。结果:获得的34株内生真菌中菌株KLBMP f0027对HepG2、HO-8910、NCI-H460、SGC-7901等细胞株均有显著活性,ID50分别为437.4、460.0、542.5、771.2。而且活性产物相对稳定,对温度、pH变化及蛋白酶不敏感。代谢过程研究显示菌株KLBMP f0027的活性产物合成与细胞生长属于部分耦联关系类型。形态学和ITS-rDNA序列分析鉴定菌株为Aspergillus ostianus strain KLBMP f0027。结论:野葛内生真菌A.ostianus strain KLBMP f0027可作为细胞毒活性候选菌株进行深入研究。     

Hypergravity induces reorientation of cortical microtubules and modifies growth anisotropy in azuki bean epicotyls

We examined the changes in the orientation of cortical microtubules during the hypergravity-induced modification of growth anisotropy (inhibition of elongation growth and promotion of lateral growth) in azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls. The percentage of cells with transverse microtubules was decreased, while that with longitudinal microtubules was increased, in proportion to the logarithm of the magnitude of gravity. The percentage of cells with longitudinal microtubules showed an increase within 0.5 h of transfer of the 1g-grown seedlings to a 300g-hypergravity condition. Lanthanum and gadolinium, blockers of calcium channels, nullified the modification of growth anisotropy and reorientation of microtubules by hypergravity. Horizontal and acropetal hypergravity modified growth anisotropy and reorientation of microtubules, as did basipetal hypergravity, and these changes were not seen in the presence of lanthanum or gadolinium. These results suggest that hypergravity changes activities of lanthanum- and gadolinium-sensitive calcium channels independently of its direction, which may lead to reorientation of cortical microtubules and modification of growth anisotropy in azuki bean epicotyls.     

Tree competition and species coexistence in a cool-temperate old-growth forest in southwestern Japan

Abstract. The growth dynamics and mode of competition between adult trees ≥ 4 cm in DBH (stem diameter at breast height 1.3 m) of eight abundant species occupying ca. 90 % of the total basal area were investigated in a 4-ha study plot (200 m × 200 m) of a cool-temperate, old-growth forest on Mount Daisen, southwestern Japan. In the study plot, 30 tree species with individuals ≥ 4.0 cm DBH co-occurred. A bimodal DBH distribution showing upper and lower-canopy layers was found for the most dominant and largest species, Fagus crenata (ca. 78 % of the total basal area), whilst other tree species showed unimodal DBH distributions corresponding mostly to the lower-canopy layer. We developed a model for individual growth incorporating both intra and interspecific competition and the degree of competitive asymmetry. Onesided interspecific competition was detected only from Fagus crenata (upper-canopy species) to Acer japonicum and Acanthopanax sciadophylloides (lower-canopy species) on the scale of the 4-ha study plot. Only Acanthopanax sciadophylloides showed symmetric intraspecific competition. However, a positive (non-competitive) interspecific relationship between adult trees prevailed over a competitive relationship; for example, individual DBH growth rate of Fagus crenata (especially lower-canopy trees) was correlated with the abundance of Acer mono. The positive relationship represented a group of species with similar habitat preference [soil type (mature or immature) caused by landslide disturbance and the presence/absence of Sasa dwarf bamboos in the understorey], where tree densities were not so high as to bring about competition. Competitive interactions between adult trees ≥ 4 cm in DBH occurred only locally between a few specific species and were suggested to be almost irrelevant to the variation in species coexistence on the 4-ha scale of cool-temperate forest. Rather, the coexistence of 30 tree species (species diversity) on this large scale was suggested to be governed by the regeneration pattern of each component species (habitat preference, seedling establishment, sapling competition) with respect to landslide disturbance.     

野葛组织内抗氧化物质初步分析

分别测定了野葛根、茎、叶ＳＯＤ、ＣＡＴ、ＰＯＤ、ＧＳＨ、Ｐｘ、Ｖｃ抗氧化物质活性,其中叶组织中含量最高;测定可深远的性蛋白和可溶性糖含量。发现可溶蛋白叶中最高,但根中可溶性糖含量远远高于茎叶。实验表明,野葛叶中也含有丰富的抗氧化物质,值得进一步研究开发。     

Effects of snow pressure on growth form and life history of tree species in Japanese beech forest

Abstract. In the cool temperate zone in Japan Fagus crenata (beech) is a highly dominating climax species, especially in the snow-rich regions at higher altitudes. The explanation for this dominance was studied with special reference to the tolerance of tree trunks to snow pressure. Traits of six tree species: trunk bend, trunk height decrease, trunk damage and basal sprouting rate were measured in Fagus forest in the Echigo Mountains, central Japan along a snow pressure gradient. The following general trends were recognized: (1) trunk bend and trunk height decrease; (2) snow pressure caused trunk injury; (3) when the trunk bend exceeded a critical angle, the number of sprouts increased remarkably. Although the tolerances were different among the six species, most of them were seriously damaged by snow pressure, and many trunks were reduced in size. On the other hand, many sprouts emerged from deformed trunks and contributed to the maintenance of the population under heavy snow pressure. F. crenata was the only species whose trunk form and maximum size were hardly influenced by snow pressure.     

葛藤不同类型叶耐旱结构的比较解剖学研究

选取葛藤栅栏组织厚度／叶肉组织厚度、栅栏组织直径、海绵组织直径、气孔密度、表皮毛密度、维管束密度、主脉厚角组织层数等旱生指标,对葛藤的3个引种类型叶的旱生结构进行比较解剖研究,结果表明3个类型的相对抗旱顺序为：美国葛藤优势最强,粉葛次之,药葛最差。     

鹅观草种质资源醇溶蛋白遗传多样性研究

以8个地理类群的90份鹅观草野生种质材料为研究对象,采用A-PAGE(酸性聚丙烯酰胺)凝胶电泳技术进行蛋白质水平遗传多样性检测.研究结果表明,来源于不同居群的鹅观草共分离出26条谱带,每个材料可以分离出5～26条迁移率不同的谱带, 平均谱带数为16.39条,其中平均多态性谱带为12.65条,多态性比例为77.22%;基于供试材料醇溶蛋白每个位点谱带出现的频率,分别计算了地理类群内多样性指数(0.345)和总多样性指数(0.471),类群间的遗传分化系数为26.8%,表明鹅观草变异的73.2% 来源于类群内;90份供试材料醇溶蛋白的Jaccard遗传相似系数变异范围为0.133 3～1.000,平均遗传相似系数为0.395 7;利用种子醇溶蛋白可将90份材料分为12类,鹅观草种质资源之间的亲缘关系呈现出一定的地域性规律;不同地理类群间的遗传多样性指数从高到低的排列顺序依次为云南＞四川＞内蒙古＞新疆＞山西＞甘肃＞宁夏＞河北.因此在进行鹅观草种质资源收集和原地保护时,建议对云南和四川地区的鹅观草种质资源应给予极大关注.